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10.1080/02701367.2006.10599339

Research quarterly for exercise and sport

Res Q Exerc Sport

Revisiting the development of time sharing using a dual motor task performance.

CognitiveTask

PRP

10.1111/j.1467-9280.2006.01690.x

Psychological science

Psychol Sci

Central interference in driving: is there any stopping the psychological refractory period?

Participants attempted to perform two tasks concurrently during simulated driving. In the choice task, they responded either manually or vocally to the number of times a visual or auditory stimulus occurred; in the braking task, they depressed a brake pedal in response to the lead car's brake lights. The time delay between the onset of the tasks' stimuli, or stimulus onset asynchrony (SOA), was varied. The tasks were differentially affected by the manipulations. Brake reaction times increased as SOA was reduced, showing the psychological refractory period effect, whereas the choice task showed large effects of the stimulus and response modalities but only a small effect of SOA. These results demonstrate that a well-practiced "simple" task such as vehicle braking is subject to dual-task slowing and extend the generality of the central-bottleneck model.

CognitiveTask

PRP

10.1037/0096-1523.32.1.149

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Backward response-level crosstalk in the psychological refractory period paradigm.

Bottleneck models of psychological refractory period (PRP) tasks suggest that a Task 1 response should be unaffected by the Task 2 response in the same trial, because selection of the former finishes before selection of the latter begins. Contrary to this conception, the authors found backward response-level crosstalk effects in which Task 2 response force requirements influenced the force-time dynamics of Task 1 responses. Specifically, Task 2 required a hard or soft keypress response. Task 1 responses were harder when the upcoming Task 2 response was to press hard rather than soft, suggesting some activation of Task 2 response parameters before Task 1 processing reached the final ballistic motor output stage. A 3rd experiment using a flankers paradigm showed that this effect did not arise from automatic activation of responses by the stimuli associated with hard and soft responses. This backward response-level crosstalk extends previous findings of backward crosstalk in the PRP paradigm by showing that crosstalk can affect motor output as well as response time and can arise even when the 2 tasks being performed are not semantically related.

CognitiveTask

PRP

10.1037/0096-1523.32.1.104

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Frequency effects in spoken and visual word recognition: evidence from dual-task methodologies.

The authors report 3 dual-task experiments concerning the locus of frequency effects in word recognition. In all experiments, Task 1 entailed a simple perceptual choice and Task 2 involved lexical decision. In Experiment 1, an underadditive effect of word frequency arose for spoken words. Experiment 2 also showed underadditivity for visual lexical decision. It was concluded that word frequency exerts an influence prior to any dual-task bottleneck. A related finding in similar dual-task experiments is Task 2 response postponement at short stimulus onset asynchronies. This was explored in Experiment 3, and it was shown that response postponement was equivalent for both spoken and visual word recognition. These results imply that frequency-sensitive processes operate early and automatically.

CognitiveTask

PRP

10.1007/s00426-005-0014-6

Psychological research

Psychol Res

Task switching and action sequencing.

We investigated if task switching affects late response processes that occur after the selection of a response. Subjects performed a sequence of two responses. The first and second response were selected, and then executed in close succession. The interresponse interval (IRI) was taken as a measure of late response processes. The two responses could either belong to different tasks (task-switch condition), or to the same task that was performed twice (task-repetition condition). In all three experiments, the IRI was found to be longer in the task-switch condition than in the task-repetition condition, consistent with the idea that task switching affected late response processes. However, the effects of the manipulation of the stimulus-onset asynchrony revealed that the tendency to perform the two responses as a sequence was reduced in the task-switch condition relative to the task-repetition condition. Thus, the data do not provide unequivocal evidence for task switching affecting late response processes. The data show, however, that task switching affected action sequencing. Two actions that do not belong to the same task context are less likely to be performed as an action sequence. We suggest that task switching interacts with higher-order control processes that cannot be studied within the traditional task-switching paradigm.

CognitiveTask

PRP

10.1007/s00426-005-0022-6

Psychological research

Psychol Res

Response-specific sources of dual-task interference in human pre-motor cortex.

It is difficult to perform two tasks at the same time. Such performance limitations are exemplified by the psychological refractory period (PRP): when participants make distinct motor responses to two stimuli presented in rapid succession, the response to the second stimulus is increasingly slowed as the time interval between the two stimuli is decreased. This impairment is thought to reflect a central limitation in selecting the appropriate response to each stimulus, but not in perceptually encoding the stimuli. In the present study, it was sought to determine which brain regions are specifically involved in response selection under dual-task conditions by contrasting fMRI brain activity measured from a response selection manipulation that increased dual-task costs, with brain activity measured from an equally demanding manipulation that affected perceptual visibility. While a number of parieto-frontal areas involved in response selection were activated by both dual-task manipulations, the dorsal pre-motor cortex, and to a lesser extent the inferior frontal cortex, were specifically engaged by the response selection manipulation. These results suggest that the pre-motor cortex is an important neural locus of response selection limitation under dual-task situations.

CognitiveTask

PRP

10.1007/s00426-005-0011-9

Psychological research

Psychol Res

Backward crosstalk effects in psychological refractory period paradigms: effects of second-task response types on first-task response latencies.

Three experiments using psychological refractory period (PRP) tasks documented backward crosstalk effects in which the nature of the second-task response influenced the first-task response latencies. Such effects are difficult to explain within currently popular bottleneck models, according to which second-task response selection does not begin until first-task response selection has finished. In Experiments 1 and 2, the first of the PRP tasks required a choice reaction time (RT) response, whereas the second task required a go/no-go decision. Task 1 responses were faster when the second task required a go response than when it required a no-go response. Experiment 3 showed that Task 1 RTs were also influenced by the complexity of second-task responses. These backward crosstalk effects indicate that significant second-task processing is carried out in time to influence first-task responses and thus challenge strictly serial bottleneck models.

CognitiveTask

PRP

10.3758/bf03193802

Psychonomic bulletin & review

Psychon Bull Rev

Location specificity in response selection processes for visual stimuli.

We used the psychological refractory period paradigm, in which participants respond to two successive tasks (T1 and T2). We created in T2 spatial and color Simon effects, known to be caused by response selection processes. Previous studies in which the spatial Simon effect was manipulated in T2 showed that this effect was underadditive, with stimulus onset asynchrony (SOA) between the targets for T1 and T2. In Experiment 1, we replicated these results with two versions of the spatial Simon effect. In contrast, in Experiment 2 we manipulated two versions of a color Simon effect, revealing an additive relation between the color Simon effect and SOA. These results suggest that the underadditivity obtained with the spatial Simon effect is due to its spatial nature, and that space may play a unique role in response selection processes.

CognitiveTask

PRP

10.1007/s00426-005-0020-8

Psychological research

Psychol Res

Task-set inertia and memory-consolidation bottleneck in dual tasks.

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations ("ignore" trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC --> BC vs. BC --> BC) in Experiment 3.

CognitiveTask

PRP

10.1007/s00426-005-0021-7

Psychological research

Psychol Res

Emergent perceptual features in the benefit of consistent stimulus-response mappings on dual-task performance.

Duncan (1979) examined all combinations of compatible and incompatible stimulus-response mappings for two spatial three-choice tasks in the psychological refractory period paradigm. Performance was better when the mappings for the tasks were consistent than when they were not, even when both mappings were incompatible. He attributed the benefit for the consistent incompatible mapping to an emergent choice between mappings when they are inconsistent that slows performance. Consistent incompatible mappings also may benefit from emergent perceptual features. The present study examined the role of emergent perceptual and mapping-choice features in two experiments that used pairs of two-choice tasks. Results similar to Duncan's were obtained with visual stimuli mapped to keypresses at short (stimulus onset asynchrony) SOAs. However, the benefit of the consistent incompatible mapping condition over the inconsistent mapping conditions was eliminated at an SOA of 1,000 ms. Furthermore, this benefit was not evident when the stimuli were auditory for Task 1 and visual for Task 2. With two-choice tasks, the benefit for consistent mappings apparently is due primarily to an emergent perceptual feature.

CognitiveTask

PRP

10.1007/s00426-005-0006-6

Psychological research

Psychol Res

Process-based and code-based interference in dual-task performance.

CognitiveTask

PRP

10.1007/s00426-005-0012-8

Psychological research

Psychol Res

What causes residual dual-task interference after practice?

Practice can dramatically reduce dual-task interference, but typically does not eliminate interference entirely. Residual interference after practice is especially large with certain non-preferred modality pairings (e.g., auditory-manual and visual-vocal). Does this residual interference imply the existence of a persistent central-processing bottleneck? To address this question, we transferred participants with previous dual-task practice to a psychological refractory period design. Although we observed residual dual-task costs in all four experiments, there was no evidence for a bottleneck, even with non-preferred modality pairings. We conclude that practice can eliminate the bottleneck limitation, but performance is still subject to other sources of interference, such as competition between central codes of the two tasks.

CognitiveTask

PRP

10.1007/s00426-005-0008-4

Psychological research

Psychol Res

On the control of visual spatial attention: evidence from human electrophysiology.

We used electrophysiological methods to track the deployment of visual spatial attention while observers were engaged in concurrent central attentional processing, using a variant of the attentional blink paradigm. Two visual targets (T1, T2) were presented at a stimulus onset asynchrony of either 200 ms or 800 ms. T1 was a white digit among white letters presented on a dark background using rapid serial visual presentation at fixation. T2 was another digit that was presented to the left or right of fixation simultaneously with a distractor digit in the opposite visual field, each followed by a pattern mask. In each T2 display, one digit was red and one was green. Half of the subjects reported the red digit and ignored the green one, whereas the other half reported the green digit and ignored the red one. T1 and T2 were reported in one block of trials, and only T2 in another block (order counterbalanced across subjects). Accuracy of report of T2 was lower at short SOA than at long SOA when both T1 and T2 were reported, but was similar across SOA when only T2 was reported. The electrophysiological results focused on the N2pc component, which was used as an index of the locus of spatial attention. N2pc was reduced in amplitude when subjects reported T1, and particularly so at the short SOA. The results suggest that attention to T1 interfered with the deployment of visual spatial attention to T2.

CognitiveTask

PRP

10.1007/s00426-005-0013-7

Psychological research

Psychol Res

The neural effect of stimulus-response modality compatibility on dual-task performance: an fMRI study.

Recent fMRI studies suggest that the inferior frontal sulcus (IFS) is involved in the coordination of interfering processes in dual-task situations. The present study aims to further specify this assumption by investigating whether the compatibility between stimulus and response modalities modulates dual-task-related activity along the IFS. It has been shown behaviorally that the degree of interference, as measured by dual-task costs, increases in modality-incompatible conditions (e.g. visual-vocal tasks combined with auditory-manual tasks) as compared to modality-compatible conditions (e.g. visual-manual tasks combined with auditory-vocal tasks). Using fMRI, we measured IFS activity when participants performed modality-compatible and modality-incompatible single and dual tasks. Behaviorally, we replicated the finding of higher dual-task costs for modality-incompatible tasks compared to modality-compatible tasks. The fMRI data revealed higher activity along the IFS in modality-incompatible dual tasks compared with modality-compatible dual tasks when inter-individual variability in functional brain organization is taken into account. We argue that in addition to temporal order coordination (Szameitat et al., 2002), the IFS is involved in the coordination of cognitive processes associated with the concurrent mapping of sensory information onto corresponding motor responses in dual-task situations.

CognitiveTask

PRP

10.1007/s00426-005-0017-3

Psychological research

Psychol Res

Modality pairing effects and the response selection bottleneck.

The present experiment examined the effects of input/output modality pairings on dual-task performance using the psychological refractory period (PRP) procedure. Four groups of participants performed two tasks composed of the same sets of inputs (visual and auditory) and the same sets of outputs (manual and vocal), but with different input/output modality pairings. Whereas modality pairings had only small effects on single-task reaction times, they had large effects on dual-task reaction times. The modality pairing effect cannot stem from differences in the difficulty of stimulus classification or response execution, because these task demands were the same across groups. The effect also does not appear to result from changes in stimulus-response compatibility. The present findings suggest dual-task interference arises not only from postponement of central operations (due to a central bottleneck), but also from a slowing of central operations whose magnitude is sensitive to the input/output modality pairings.

CognitiveTask

PRP

10.1016/j.actpsy.2005.07.002

Acta psychologica

Acta Psychol (Amst)

Regarding time-sharing with convergent operations.

This study contrasts the structural bottleneck and the resource view of attentional limits in time-sharing performance. The research incorporated features of the psychological refractory period (PRP) and the relative priority paradigm designed to maximize joint performance. A main distinction between the two attention views was their prediction on the extent that graded performance tradeoff was possible with graded priority changes. Detailed analysis of the performance and time-sharing strategies called into question the conclusions based exclusively on the PRP paradigm.

CognitiveTask

PRP

10.1007/s00426-005-0015-5

Psychological research

Psychol Res

Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study.

A crucial demand in dual tasks suffering from a capacity limited processing mechanism is task-order scheduling, i.e. the control of the order in which the two component tasks are processed by this limited processing mechanism. The present study aims to test whether the lateral prefrontal cortex (LPFC) is associated with this demand. For this, 15 participants performed a psychological refractory paradigm (PRP) type dual task in an event-related functional magnetic resonance (fMRI) experiment. In detail, two choice reaction tasks, a visual (response with right hand) and an auditory (response with left hand), were presented with a temporal offset of 200 ms, while the participants were required to respond to the tasks in the order of their presentation. Importantly, the presentation order of the tasks changed randomly. Based on previous evidence, we argue that trials in which the present task order changed as compared to the previous trial (different-order trials) impose higher demands on task coordination than same-order trials do. The analyses showed that cortical areas along the posterior part of the left inferior frontal sulcus as well as the right posterior middle frontal gyrus were more strongly activated in different-order than in same-order trials, thus supporting the conclusion that one function of the LPFC for dual-task performance is the temporal coordination of two tasks. Furthermore, it is discussed that the present findings favour the active scheduling over the passive queuing hypothesis of dual-task processing.

CognitiveTask

PRP

10.1007/s00426-005-0016-4

Psychological research

Psychol Res

A neuropsychological assessment of dual-task costs in closed-head injury patients using Cohen's effect size estimation method.

A test of whether patients suffering from a severe closed-head injury (CHI) were affected by disproportionate dual-task costs compared to those of healthy control participants was carried out through a direct comparison of CHI effects on dual-task (psychological refractory period, or PRP) performance and on single-task performance. In the dual-task condition of the present experiment, independent choice-responses were required to two sequential stimuli presented at a variable stimulus onset asynchrony (SOA). A significant delay of the reaction time (RT) to the second stimulus was reported by both CHI patients and controls at short (SOA) compared to long SOA, i.e., a PRP effect. The PRP effect was more pronounced for CHI patients than controls. In the single-task condition, a single choice-response was required to a stimulus presented in isolation. The RT produced by CHI patients in the single-task paradigm was longer than the RT produced by controls. CHI effects on dual-task performance and on single-task performance were compared following (1) their transformation into Cohen's ds, and (2) the application of a correction algorithm taking into account the different reliability of single-task and dual-task measures. The analysis of Cohen's ds revealed that CHI effects on performance were, if anything, smaller in the dual-task condition than in the single-task condition. The results imply that CHI patient's slower responding in single- and dual-task performance reflects a single common cause--slowing of the central processing.

CognitiveTask

PRP

10.1037/0096-1523.31.4.790

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Testing the predictions of the central capacity sharing model.

The divergent predictions of 2 models of dual-task performance are investigated. The central bottleneck and central capacity sharing models argue that a central stage of information processing is capacity limited, whereas stages before and after are capacity free. The models disagree about the nature of this central capacity limitation. The central bottleneck model claims that central processing acts on only 1 task at a time and, therefore, constitutes a bottleneck that processes tasks serially. The central capacity sharing model postulates that the central stage is a limited-capacity parallel processor that divides resources among to-be-performed tasks. As a result of this difference, in the psychological refractory period paradigm, the central capacity sharing model predicts that lengthening Task 2 precentral processing will improve Task 1 performance at short stimulus onset asynchronies, whereas the central bottleneck model does not. Results of 2 experiments confirm the prediction of the central capacity sharing model.

CognitiveTask

PRP

10.1097/01.jcp.0000165740.22377.6d

Journal of clinical psychopharmacology

J Clin Psychopharmacol

Double-blind, placebo-controlled, crossover trial of clozapine plus glycine in refractory schizophrenia negative results.

CognitiveTask

PRP

10.1111/j.0956-7976.2005.01526.x

Psychological science

Psychol Sci

The beneficial effect of concurrent task-irrelevant mental activity on temporal attention.

It is believed that the human cognitive system is fundamentally limited in deploying attention over time. This limitation is reflected in the attentional blink, the impaired ability to identify the second of two visual targets presented in close succession. We report the paradoxical finding that the attentional blink is significantly ameliorated when observers are concurrently engaged in distracting mental activity, such as free-associating on a task-irrelevant theme or listening to music. This finding raises questions about the fundamental nature of the attentional blink, and suggests that the temporal dynamics of attention are determined by task circumstances that induce either a more or a less distributed state of mind.

CognitiveTask

PRP

10.1007/s00221-005-2281-2

Experimental brain research

Exp Brain Res

Central processing overlap modulates P3 latency.

Two experiments examined the issue of the functional mechanisms exerting a modulatory effect on the latency of the P3. In experiment 1, using a psychological refractory period (PRP) paradigm, two sequential stimuli (T(1) and T(2)) were presented in each trial at varying stimulus onset asynchronies (SOAs), each requiring a speeded choice response. Substantial lengthening of the reaction time to T(2) was observed as SOA decreased (i.e., PRP effect). A systematic investigation of the T(2)-locked P3 component amplitude and latency was undertaken to discover whether either of these P3 parameters was correlated with the PRP effect. The results showed lengthening of the T(2)-locked P3 component latency as SOA was decreased, and, across subjects, a positive correlation between the PRP effect and P3 latency lengthening. No SOA-dependent P3 amplitude variation was observed. In experiment 2, the P3 component was measured under single-task conditions. P3 amplitude was higher under single-task than under dual-task conditions, but no SOA-dependent latency variations were observed in this experiment. Overall, the results of both experiments support the notion that part of the processing reflected in P3 activity occurs at or after the locus of the PRP effect, thus suggesting strongly that central mechanisms are involved in P3 latency variations.

CognitiveTask

PRP

10.3758/bf03196842

Perception & psychophysics

Percept Psychophys

Revisiting within-modality and cross-modality attentional blinks: effects of target-distractor similarity.

When two masked targets (T1 and T2) require attention and are presented within half a second of each other, the report accuracy for T2 is reduced, relative to when the two targets are presented farther apart in time. This effect is known as the attentional blink (AB). Potter, Chun, Banks, and Muckenhoupt (1998) argued that all AB-like effects observed when at least one of the targets was presented outside of the visual modality did not represent true instances of the AB, but instead were artifacts of task-set switching. However, in the Potter et al. experiments the presence or absence of task-set switching opportunities was confounded with the T2 task, as well as the alphanumeric class of T2 with respect to the distractors. In the present experiment, we examine the influence of T1 alphanumeric class, T2 alphanumeric class, and switching operations in a fully crossed design that unconfounds these factors. In contrast to the conclusions of Potter et al., the present results suggest that the T2 alphanumeric class can account for the pattern of ABs observed across conditions, without necessarily implicating a separate switch cost. The implications for theoretical models of the AB and the debate over the validity of cross-modal ABs are discussed.

CognitiveTask

PRP

10.1371/journal.pbio.0030037

PLoS biology

PLoS Biol

Parsing a cognitive task: a characterization of the mind's bottleneck.

Parsing a mental operation into components, characterizing the parallel or serial nature of this flow, and understanding what each process ultimately contributes to response time are fundamental questions in cognitive neuroscience. Here we show how a simple theoretical model leads to an extended set of predictions concerning the distribution of response time and its alteration by simultaneous performance of another task. The model provides a synthesis of psychological refractory period and random-walk models of response time. It merely assumes that a task consists of three consecutive stages-perception, decision based on noisy integration of evidence, and response-and that the perceptual and motor stages can operate simultaneously with stages of another task, while the central decision process constitutes a bottleneck. We designed a number-comparison task that provided a thorough test of the model by allowing independent variations in number notation, numerical distance, response complexity, and temporal asynchrony relative to an interfering probe task of tone discrimination. The results revealed a parsing of the comparison task in which each variable affects only one stage. Numerical distance affects the integration process, which is the only step that cannot proceed in parallel and has a major contribution to response time variability. The other stages, mapping the numeral to an internal quantity and executing the motor response, can be carried out in parallel with another task. Changing the duration of these processes has no significant effect on the variance.

CognitiveTask

PRP

10.1037/0096-1523.31.1.122

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Dual-task performance with ideomotor-compatible tasks: is the central processing bottleneck intact, bypassed, or shifted in locus?

The present study examined whether the central bottleneck, assumed to be primarily responsible for the psychological refractory period (PRP) effect, is intact, bypassed, or shifted in locus with ideomotor (IM)-compatible tasks. In 4 experiments, factorial combinations of IM- and non-IM-compatible tasks were used for Task 1 and Task 2. All experiments showed substantial PRP effects, with a strong dependency between Task 1 and Task 2 response times. These findings, along with model-based simulations, indicate that the processing bottleneck was not bypassed, even with two IM-compatible tasks. Nevertheless, systematic changes in the PRP and correspondence effects across experiments suggest that IM compatibility shifted the locus of the bottleneck. The findings favor an engage-bottleneck-later hypothesis, whereby parallelism between tasks occurs deeper into the processing stream for IM- than for non-IM-compatible tasks, without the bottleneck being actually eliminated.

CognitiveTask

PRP

10.1080/02643290442000491

Cognitive neuropsychology

Cogn Neuropsychol

Unitary attention in callosal agenesis.

The interhemispheric organisation of two specific components of attention was investigated in three patients affected by partial or complete agenesis of the corpus callosum. A visuospatial component of attention was explored using a visual search paradigm in which target and distractors were displayed either unilaterally within a single visual hemifield, or bilaterally across both visual hemifields in light of prior work indicating that split-brain patients were twice as fast to scan bilateral displays compared to unilateral displays. A central component of attention was explored using a psychological refractory period (PRP) paradigm in which two visual stimuli were presented laterally at various stimulus onset asynchronies (SOAs), with each stimulus associated with a different speeded two-alternative choice task. The stimulus-response compatibility in the second task was systematically manipulated in this paradigm, in light of prior work indicating that split-brain patients exhibited a close-to-normal PRP effect (i.e., slowing of the second response as SOA is decreased), with, however, abnormally decreasing effects of the manipulation of the response mapping on the second task speed as SOA was decreased. The present results showed that, although generally slower than normals in carrying out the two tasks, the performance of each of the three acallosal patients was formally equivalent to the performance of a matched control group of normal individuals. In the visual search task, the search rate of the acallosal patients was the same for unilateral and bilateral displays. Furthermore, in the PRP task, there was more mutual interference between the lateralised tasks for the acallosal patients than that evidenced in the performance of the matched control group. It is concluded that the visuospatial component and the central component of attention in agenesis of the corpus callosum are interhemispherically integrated systems.

CognitiveTask

PRP

10.1037/0882-7974.19.4.649

Psychology and aging

Psychol Aging

Can practice overcome age-related differences in the psychological refractory period effect?

Can dual-task practice remove age-related differences in the psychological refractory period (PRP) effect? To answer this question, younger and older individuals practiced 7 blocks of a PRP design, in which Task 1 (T1) required a vocal response to an auditory stimulus and Task 2 (T2) required a manual response to a visual stimulus (Experiment 1). The results showed that practice did not reduce, but rather increased, age-related differences in PRP interference. Using the trained individuals, the introduction of a less complex new T1 (Experiment 2) or a less complex new T2 (Experiment 3) with the task previously practiced reduced the PRP interference but only in older adults. The authors propose that older adults suffer from a large task-switch cost that is more sensitive to task complexity than to the amount of practice.

CognitiveTask

PRP

10.1037/0096-1523.30.5.913

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Repetition blindness: out of sight or out of mind?

Does repetition blindness represent a failure of perception or of memory? In Experiment 1, participants viewed rapid serial visual presentation (RSVP) sentences. When critical words (C1 and C2) were orthographically similar, C2 was frequently omitted from serial report; however, repetition priming for C2 on a postsentence lexical decision task was equivalent whether or not C1 was similar to C2. In Experiment 2, participants monitored RSVP sentences for a predetermined target. Participants frequently failed to detect the target when it was preceded by an orthographically similar word. In Experiment 3, the authors investigated the role of the attentional blink in this effect. These experiments suggest that repetition blindness is a failure of conscious perception, consistent with predictions of the token-individuation hypothesis.

CognitiveTask

PRP

10.1037/0096-1523.30.5.795

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Virtually no evidence for virtually perfect time-sharing.

An examination of previous claims for virtually perfect time-sharing in dual-task situations reveals confounding effects that may have obscured dual-task interference. Two experiments are conducted in which these confounding effects are minimized, revealing statistically significant dual-task interference. These results support the hypothesis that human information processing is dominated by a structural central capacity limitation and call into question the hypothesis that dual-task interference can be eliminated by meeting the 5 conditions outlined by D. Meyer and D. Kieras (1999).

CognitiveTask

PRP

10.1037/0882-7974.19.3.416

Psychology and aging

Psychol Aging

Aging and input processing in dual-task situations.

The psychological refractory period (PRP) paradigm was used to test whether older participants suffer from input interference in dual-task situations. Young (24 years) and older (57 years) adults gave speeded responses to 2 successively presented stimuli. The results showed increased susceptibility of older participants to input interference. Further experiments revealed that this input interference is related to the salience of the 2nd stimulus and that it is specific to older participants. Our findings indicate that parallel processing at the input stages of dual-task performance requires cognitive control. An age-related decline in the control of input processes should be considered as one source of age effects in dual-task performance.

CognitiveTask

PRP

10.1007/s00221-004-2006-y

Experimental brain research

Exp Brain Res

Closed head injury and perceptual processing in dual-task situations.

Using a classical psychological refractory period (PRP) paradigm we investigated whether increased interference between dual-task input processes is one possible source of dual-task deficits in patients with closed-head injury (CHI). Patients and age-matched controls were asked to give speeded motor reactions to an auditory and a visual stimulus. The perceptual difficulty of the visual stimulus was manipulated by varying its intensity. The results of Experiment 1 showed that CHI patients suffer from increased interference between dual-task input processes, which is related to the salience of the visual stimulus. A second experiment indicated that this input interference may be specific to brain damage following CHI. It is not evident in other groups of neurological patients like Parkinson's disease patients. We conclude that the non-interfering processing of input stages in dual-tasks requires cognitive control. A decline in the control of input processes should be considered as one source of dual-task deficits in CHI patients.

CognitiveTask

PRP

10.1037/0096-1523.30.3.566

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

The costs of changing the representation of action: response repetition and response-response compatibility in dual tasks.

In 5 experiments, the authors investigated the costs associated with repeating the same or a similar response in a dual-task setting. Using a psychological refractory period paradigm, they obtained response-repetition costs when the cognitive representation of a specific response (i.e., the category-response mapping) changed (Experiment 1) but benefits when it did not change (Experiment 2). The analogous pattern of results was found for conceptually similar (i.e. compatible) responses. Response-response compatibility costs occurred when the cognitive representations of the compatible responses were different (Experiments 3A & 3B), but compatibility benefits occurred when they were the same (Experiment 4). The authors interpret the costs of repeating an identical or compatible response in terms of a general mechanism of action selection that involves coding the task-specific meaning of a response.

CognitiveTask

PRP

10.3758/bf03206464

Psychonomic bulletin & review

Psychon Bull Rev

Dissociating sources of dual-task interference using human electrophysiology.

In the psychological refractory period (PRP) paradigm, two unmasked targets are presented, each of which requires a speeded response. Response times to the second target (T2) are slowed when T2 is presented shortly after the first target (T1). Electrophysiological studies have previously shown that the P3 event-related potential component is not delayed during T2 response slowing in the PRP paradigm, but that the lateralized readiness potential is delayed, which suggests a bottleneck on response selection operations but not on stimulus identification. Recently, researchers (Arnell & Duncan, 2002; Jolicoeur & Dell'Acqua, 1999) observed T2 response slowing in an encoding-speeded response (ESR) paradigm where T2 followed a masked T1 that required identification but not a speeded response. T2 response slowing in the ESR paradigm is often indistinguishable from that in the PRP paradigm, prompting some researchers to postulate a common processing bottleneck for the two paradigms. With the use of the ESR paradigm, we observed T2 response slowing and, in contrast to the PRP paradigm, we also observed corresponding P3 delays. The results suggest that dissociable bottlenecks underlie the dual-task costs from the two paradigms.

CognitiveTask

PRP

10.1097/01.alc.0000121652.84754.30

Alcoholism, clinical and experimental research

Alcohol Clin Exp Res

Fast, but error-prone, responses during acute alcohol intoxication: effects of stimulus-response mapping complexity.

Although moderate doses of alcohol can impair performance on tasks that require information processing, little is known about the locus of the alcohol effects within the processing stream. This study used a psychological refractory period paradigm to investigate the effect of alcohol on the central, cognitive stage of information processing when task complexity is manipulated by altering stimulus-response compatibility. Thirty-four healthy male social drinkers were assigned to one of two groups (n = 17) that performed two tasks. Each trial consisted of a task 1 stimulus (tone) followed by a task 2 stimulus (letter) that was presented after one of four stimulus onset asynchronies (50, 200, 500, or 1100 msec). A baseline test of performance was obtained before the groups received a beverage containing either 0.0 g/kg (placebo) or 0.65 g/kg alcohol. Both groups were retested when blood alcohol concentration (BAC) was increasing and was decreasing. The alcohol group made significantly more errors in task 1 compared with their drug-free baseline measure during the ascending phase of the BAC curve, and error rates increased to a greater extent for the more complex arbitrary stimulus-response mapping condition. Moreover, this increase in errors continued unabated during the descending phase of the BAC curve. Increasing BACs also slowed performance (longer reaction time), but unlike errors, reaction time returned to drug-free baseline levels when BAC was decreasing. The results provide evidence that an acute dose of alcohol can impair one aspect of the central, cognitive stages of information processing. The possibility that errors in information processing remain during decreasing BACs even after processing speed has returned to drug-free levels has important practical implications relating to the detrimental consequences of acute alcohol intoxication.

CognitiveTask

PRP

10.1016/j.bbr.2003.09.003

Behavioural brain research

Behav Brain Res

Pre-pulse inhibition of the acoustic startle eye-blink in the Göttingen minipig.

Pre-pulse inhibition (PPI) of the startle response is a measure of sensorimotor gating which has been frequently shown to be deficient in schizophrenic patients. In humans it is typically measured as the attenuation of the startle eye-blink reflex EMG when a startle eliciting noise is preceded by a weak white noise pre-pulse (PP), the interval between the PP and the startle noise stimulus (SNS) determining the degree of inhibition. Aiming at developing a new animal model of schizophrenia, we have investigated the acoustic startle eye-blink and PPI in 10 Göttingen minipigs. The stimuli and the block design of the stimulation were similar to paradigms used in human research. Initially the startle habituation across trials and blocks, secondarily the PPI at PP to SNS intervals of 30, 60, 120, 220, 520, 1020 and 2020 ms was investigated. One pig out of ten did not have a startle response, and three other pigs did not have a startle response of a sufficient magnitude to demonstrate the PPI seen in the other six pigs at the expected PP intervals of 60, 120, and 220 ms. Maximal inhibition was seen at the 220 ms interval (mean PPI 58.6%, range -18.4 to 94.6%, N = 9). Most of the results in the pigs are in accordance with findings in studies of the human startle eye-blink EMG and this initial study promotes further studies and the use of the PPI measure in the validation of minipig models of psychiatric disorders.

CognitiveTask

PRP

Revista de neurologia

Rev Neurol

[Experimental bases for evaluating attention in attention deficit hyperactivity disorder].

The experimental evaluation of the time variable in attention enables us to distinguish between what can be considered as its normal and its pathological behaviour. It has proved to be useful in evaluating the population suffering from attention disorders (attention deficit hyperactivity disorder, frontal lesions, etc.) as a means of defining the extent to which the patient is affected by the disorder and also in designing a training programme for later use. The most notable attentional paradigms are attentional blink (AB), repetition blindness, change detection, psychological refractory period, task switching, and negative and positive priming. Patients with ADHD showed a poor capacity for identification of target stimuli (T1) in attentional blink tests; they also displayed a significantly higher attentional blink than that observed in the control group, especially for time intervals between 300 and 600 ms after the first target letter (T1). Attention is a complex, dynamic concept derived from the interaction of different neuroanatomical systems. There are several different theories to explain disorders affecting the attentional skills. One of the explanations comes into being as a result of linking sustained attentional disorder with impulsiveness and hyperactive behaviour. Another is related to selective attention disorders. This distinction allows us to discern the involvement of two systems that will give rise to different clinical symptoms and hence the presence of attentional subtypes. Thus, for example, it is possible to find a first group with disorders affecting attention, impulsiveness and disinhibition, and a second group with slow reactions and in a state of confusion and/or inattention as regards the events taking place around them (but they do not have impulsiveness or disinhibition).

CognitiveTask

PRP

10.3758/bf03196550

Psychonomic bulletin & review

Psychon Bull Rev

Inhibition of return: a graphical meta-analysis of its time course and an empirical test of its temporal and spatial properties.

Immediately after a stimulus appears in the visual field, there is often a short period of facilitated processing of stimuli at or near this location. This period is followed by one in which processing is impaired, rather than facilitated. This impairment has been termed inhibition of return (IOR). In the present study, the time course of this phenomenon was examined in two ways. (1) A graphical meta-analysis plotted the size of the effect as a function of the stimulus onset asynchrony (SOA) of the two stimuli. This analysis showed that IOR is impressively stable for SOAs of 300-1,600 msec. It also showed that the literature does not provide any clear sense of the duration of IOR. (2) An empirical approach was, therefore, taken to fill this gap in our knowledge of IOR. In three experiments, IOR was tested using SOAs between 600 and 4,200 msec. IOR was robust for approximately 3 sec and appeared to taper off after this point; the observed duration varied somewhat as a function of the testing conditions. In addition, for the first second, the degree of inhibition was inversely related to distance of the target from the original stimulus, but for the next 2 sec this spatial distribution was not observed. Theories of the mechanisms and function of IOR must conform to these spatial and temporal properties.

CognitiveTask

PRP

10.1037/h0087434

Canadian journal of experimental psychology = Revue canadienne de psychologie experimentale

Can J Exp Psychol

A paradigm for exploring what the mind does while deciding what it should do.

One widespread belief about automatic mental processes is that, among other characteristics, they are involuntary. No initial conscious intent is necessary because such processing is stimulus initiated. This claim was studied in the context of a novel task-choice procedure in which subjects were informed as to which of two tasks they should perform on a letter string either well in advance of a target, or when the target appeared. The hypothesis that initial processing of the target occurs without intent predicts that the effect of contrast reduction will be absent when the task cue appears synchronously with the target. This is because initial processing of the target should be completed during the time taken to decode the task cue. The results are inconsistent with this account. Instead, they support an account in which functional target processing is delayed until the subject knows what the task is. Some directions for future investigations are noted.

CognitiveTask

PRP

10.1037/0096-1523.29.6.1267

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Still no evidence for perfect timesharing with two ideomotor-compatible tasks: a reply to Greenwald (2003).

For 30 years, A. G. Greenwald and H. G. Shulman's (1973) psychological refractory period (PRP) study has been cited as evidence for perfect timesharing with ideomotor (IM)-compatible tasks. Recently, M.-C. Lien, R. W. Proctor, and P. A. Allen (2002) failed to replicate these results and concluded that IM compatibility is neither necessary nor sufficient to eliminate the PRP effect. A. G. Greenwald (2003) attributed Lien et al.'s nonreplication to the use of (a) a non-IM-compatible task, (b) varied trial spacing, and/or (c) inappropriate instructions. The authors of the present article argue that the first 2 factors are not critical and that instructions merely affect the criterion for speed versus accuracy. In each of Greenwald's experiments, dual-task costs were evident on response time or error rates. Furthermore, the small dual-task costs in his study are consistent with a bottleneck model. Thus, Greenwald (2003) does not provide evidence that IM-compatible tasks enable perfect timesharing.

CognitiveTask

PRP

10.1037/0096-1523.29.6.1126

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

The locus of redundant-targets and nontargets effects: evidence from the psychological refractory period paradigm.

In target detection tasks, responses are faster when displays have 2 targets (redundant-targets effect; RTE) and slower when they have no targets (nontargets effect; NTE) relative to displays with a single target. The psychological refractory period paradigm was used to localize these effects. In Experiment 1, participants classified tones as high or low and then classified letters as targets or nontargets after a short or long stimulus onset asynchrony (SOA). The magnitudes of the RTE and NTE did not depend on SOA. In Experiment 2, the order of the tasks was reversed, and at short SOAs the RTE and NTE had similar magnitudes for both tone discrimination and target detection responses. These findings suggest that the RTE and NTE arise during response selection. Interactive effects of tone pitch with the number and type of target features were also observed, and these were tentatively interpreted as synesthetic effects.

CognitiveTask

PRP

10.1037/0096-1523.29.5.1036

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Absence of perceptual processing during reconfiguration of task set.

The authors manipulated stimulus contrast and response-stimulus interval in the alternating runs paradigm to investigate whether early processing could be carried out during a task switch. Subjects alternated between judging the magnitude and the parity of a digit. The results suggested that early processing was not carried out during the task switch (Experiment 1), even in the absence of potentially confounding auditory or visual warning signals (Experiment 2). This processing was, however, carried out in parallel with a demanding operation in a 2nd task (Experiment 3), using the display parameters of Experiments 1 and 2 in the psychological refractory period paradigm. It is concluded that, functionally, task switching may impose a hard bottleneck even for very early stimulus processing. ((c) 2003 APA, all rights reserved)

CognitiveTask

PRP

10.1037/0096-1523.29.5.965

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

The psychological refractory period of stopping.

The author examined whether the act of control of stopping is subject to the psychological refractory period (PRP) and whether stopping causes a PRP for the processing of subsequent stimuli. The task was to execute or to stop a rapid finger tapping. PRP interference was predicted for double-stimulation trials, in which 2 signals to tap or stop were presented in rapid succession. The experiments showed that stopping ongoing action is subject to and produces PRP interference similar to starting. Responses to signals to continue an ongoing action do not produce PRP interference. The results suggest that selection or initiation of new responses, but not mere response choice, constituted the processing bottleneck that caused the PRP in the present task. Further results indicate that the inhibition of not-yet-executed actions, in contrast to action termination, does not suffer PRP interference and that response inhibitions and terminations should be distinguished. ((c) 2003 APA, all rights reserved)

CognitiveTask

PRP

10.3758/bf03194816

Perception & psychophysics

Percept Psychophys

Dual-task interference with equal task emphasis: graded capacity sharing or central postponement?

Most studies using the psychological refractory period (PRP) design suggest that dual-task performance is limited by a central bottleneck. Because subjects are usually told to emphasize Task 1, however, the bottleneck might reflect a strategic choice rather than a structural limitation. To evaluate the possibility that central operations can proceed in parallel, albeit with capacity limitations, we conducted two dual-task experiments with equal task emphasis. In both experiments, subjects tended to either group responses together or respond to one task well before the other. In addition, stimulus-response compatibility effects were roughly constant across stimulus onset asynchronies (SOAs). At the short SOA, compatibility effects also carried over onto response times for the other task. This pattern of results is difficult to reconcile with the possibility that subjects share capacity roughly equally between simultaneous central operations. However, this pattern is consistent with the existence of a structural central bottleneck.

CognitiveTask

PRP

10.1076/jcen.25.3.361.13811

Journal of clinical and experimental neuropsychology

J Clin Exp Neuropsychol

Dual target identification and the attentional blink in Parkinson's disease.

In healthy adults, deficits in identifying a second target following a previously attended target in Rapid Serial Visual Presentation (RSVP) occur between intertarget intervals of approximately 100-500 ms. This Attentional Blink (AB) is investigated in nondemented medicated Parkinson's patients using a modification of the standard paradigm that required the identification of two red letters embedded in a black letter distractor stream. Parkinson's patients and controls produced an equivalent AB, although with a different pattern of errors. Thus, the processing and clearance of information was largely preserved in nondemented Parkinson's patients, without evidence of bradyphrenia. However, perseveration of earlier RSVP items in short-term memory was thought to explain the different pattern of errors.

CognitiveTask

PRP

10.1037/0096-1523.29.3.692

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Task switching and response correspondence in the psychological refractory period paradigm.

Three experiments examined the effects of task switching and response correspondence in a psychological refractory period paradigm. A letter task (vowel-consonant) and a digit task (odd-even) were combined to form 4 possible dual-task pairs in each trial: letter-letter, letter-digit, digit-digit, and digit-letter. Foreknowledge of task transition (repeat or switch) and task identity (letter or digit) was varied across experiments: no foreknowledge in Experiment 1, partial foreknowledge (task transition only) in Experiment 2, and full foreknowledge in Experiment 3. For all experiments, the switch cost for Task 2 was additive with stimulus onset asynchrony, and the response-correspondence effect for Task 2 was numerically smaller in the switch condition than in the repeat condition. These outcomes suggest that reconfiguration for Task 2 takes place after the central processing of Task 1 and that the crosstalk correspondence effect is due to response activation by way of stimulus-response associations.

CognitiveTask

PRP

10.1037/0096-1523.29.3.556

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Online order control in the psychological refractory period paradigm.

The authors examined the role of online order control in the psychological refractory period (PRP) paradigm. In the first 2 experiments, participants switched between color-letter and letter-color orders so that subtask order was isolated as the only element being switched. The results indicated that order switching impaired the 2 PRP responses and modulated the PRP effect. Importantly, these effects were reduced by advance preparation, demonstrating that order representation was activated before the subtasks themselves. Preparation for subtask order did not reflect preparation for hand order, as shown in Experiment 3. In addition, there was no evidence that subtask order information dissipated between trials. The relevance of the results to theories of the PRP paradigm and task switching is discussed.

CognitiveTask

PRP

10.1037/0096-1523.29.2.280

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Vanishing dual-task interference after practice: has the bottleneck been eliminated or is it merely latent?

Practice can, in some cases, largely eliminate measured dual-task interference. Does this absence of interference indicate the absence of a processing bottleneck (defined as an inability to carry out certain stages in parallel)? The authors show that a bottleneck need not produce any observable interference, provided that there is no temporal overlap in the demand for bottleneck stages on the 2 tasks. Such a "latent" bottleneck is especially likely after practice, when central stages are short. The authors provide new evidence that a latent bottleneck occurred for a participant who produced no interference in M. Van Selst, E. Ruthruff, and J. C. Johnston (1999). These findings demonstrate that the absence of dual-task interference does not necessarily indicate the absence of a processing bottleneck.

CognitiveTask

PRP

10.3758/bf03196472

Psychonomic bulletin & review

Psychon Bull Rev

Concurrent task effects on memory retrieval.

Previous studies combining continuous free recall with a concurrent task have generally shown that concurrent tasks impose fairly negligible effects on memory retrieval. By contrast, dual-task studies employing either cued recall or semantic retrieval reveal gross memory impairment and suggest that retrieval is delayed by the centrally demanding phase of the concurrent tasks (i.e., response selection). To explore this conflict, subjects performed continuous free recall while carrying out a serial-choice-response time (RT) task, as in the previous free recall studies. Unlike these previous studies, however, the choice-RT task utilized arbitrary stimulus-response mappings in order to increase the proportion of time devoted to the centrally demanding response selection phase. Recall total was reduced significantly, and recall latency was slowed substantially.

CognitiveTask

PRP

10.1037/h0087409

Canadian journal of experimental psychology = Revue canadienne de psychologie experimentale

Can J Exp Psychol

Lengthening the duration of response execution does not modulate blindness to action-compatible stimuli.

Action-compatible blindness refers to the finding that target stimuli are perceived less frequently if they are presented during the planning or execution of a compatible action (e.g., a left arrow presented during a left manual key press) than during an incompatible action (Müsseler & Hommel, 1997 a, b). We investigated the effect of lengthening the response execution phase in the action-compatible blindness paradigm by requiring subjects to tap a response key once or three times on the assumption that tapping three times would increase the duration of the execution phase of the response. Prior research (e.g., Stevanovski, Oriet, & Jolicoeur, 2002; Wühr & Müsseler, 2001) has shown that larger blindness effects are observed for targets presented during the execution phase of a response than after the response has been made. We investigated whether a larger blindness effect would be observed in the three-tap condition than in the one-tap condition, or whether lengthening the duration of the response would extend the time course of the blindness effect. Neither of these possibilities was supported by the data irrespective of whether the number of taps to be made was blocked or mixed within a block of trials. The results are discussed in terms of current accounts of action-compatible blindness and the possible cognitive differences between making a single response and repeating a response.

CognitiveTask

PRP

10.1037//0096-1523.29.1.3

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

A central capacity sharing model of dual-task performance.

The authors present the central capacity sharing (CCS) model and derive equations describing its behaviors to explain results from dual-task situations. The predictions of the CCS model are contrasted with those of the central bottleneck model. The CCS model predicts all of the hallmark effects of the psychological refractory period (PRP) pardigm: -1 slope of the PRP effect at short stimulus onset asynchronies (SOAs), underadditivity of precentral Task 2 manipulations, additivity of central or postcentral Task 2 manipulations with SOA, and carry forward to Task 2 of Task 1 precentral or central manipulations at short SOAs. The CCS model also predicts that Task 1 response times increase with decreasing SOA. The model is a viable alternative to the central bottleneck model.

CognitiveTask

PRP

10.1037//1064-1297.10.4.417

Experimental and clinical psychopharmacology

Exp Clin Psychopharmacol

Constraints on information processing under alcohol in the context of response execution and response suppression.

This study tested the degree that alcohol restricts information processing on tasks requiring response execution and response suppression. A dual task required 12 participants to respond to 2 task stimuli (Tasks 1 and 2) presented in close succession. The task was performed before and after receiving 3 alcohol doses (placebo, 0.45 g/kg, and 0.65 g/kg) administered on separate days in a counterbalanced order. Alcohol increased task interference, as evidenced by increased time to respond to Task 2. Impairment was comparable regardless of whether Task 1 required a response to be executed or suppressed. The evidence supports a resource limitation account that argues that alcohol reduces capacity to process information required for execution and suppression of responses.

CognitiveTask

PRP

10.1162/089892902760807195

Journal of cognitive neuroscience

J Cogn Neurosci

Localization of executive functions in dual-task performance with fMRI.

We report a study that investigated the neuroanatomical correlates of executive functions in dual-task performance with functional magnetic resonance imaging. Participants performed an auditory and a visual three-choice reaction task either separately as single tasks or concurrently as dual tasks. In the dual-task condition, two stimuli were presented in rapid succession to ensure interference between the component tasks (psychological refractory period). The behavioral data showed considerable performance decrements in the dual-task compared to the single-task condition. Dual-task-related activation was detected with two different neuroimaging methods. First, we determined dual-task-related activation according to the method of cognitive subtraction. For that purpose, activation in the dual-task was compared directly with activation in the single-task conditions. This analysis revealed that cortical areas along the inferior frontal sulcus (IFS), the middle frontal gyrus (MFG), and the intraparietal sulcus (IPS) are involved in dual-task performance. The results of the subtraction method were validated with the method of parametric manipulation. For this purpose, a second dual-task condition was introduced, where the difficulty of the dual-task coordination was increased compared with the first dual-task condition. As expected, behavioral dual-task performance decreased with increased dual-task difficulty. Furthermore, the increased dual-task difficulty led to an increase of activation in those cortical regions that proved to be dual-task related with the subtraction method, that is, the IFS, the MFG, and the IPS. These results support the conclusion that dorsolateral prefrontal and superior parietal cortices are involved in the coordination of concurrent and interfering task processing.

CognitiveTask

PRP

10.1348/000711002760554589

The British journal of mathematical and statistical psychology

Br J Math Stat Psychol

A tandem random walk model of the SAT paradigm: response times and accumulation of evidence.

The speed-accuracy trade-off (SAT) paradigm forces participants to trade response speed for information accuracy by presenting them with a response signal at variable times after the onset of processing to which they must give an immediate response (within 300 ms). The processes that underlie the paradigm, especially those affecting response times, are not completely understood. Also, the extent to which the paradigm might affect the evidence accumulation process is still unclear. By testing several different sets of assumptions, we present a random walk model for the SAT paradigm that qualitatively explains both accuracy and response time data. The model uses a tandem random walk, with two possible continuations in a second phase which begins after the response signal. If a boundary is not reached during phase one, the walk transfers the current sum (relative to the size of the boundaries) from phase one to phase two in the form of bias, with drift rate equal to zero. If, however, a boundary is reached in phase one, the second phase starts from zero (no bias) with a strong drift rate towards the previously reached boundary. The model also incorporates a psychological refractory period: a delay in the onset of a second task when two tasks are presented in close succession. The model is consistent with the idea that information about the evidence accumulation rate is not contaminated by the paradigm.

CognitiveTask

PRP

10.1007/s00426-002-0101-x

Psychological research

Psychol Res

All-or-none bottleneck versus capacity sharing accounts of the psychological refractory period phenomenon.

The goal of the present experiment was to test the predictions of Central Bottleneck and Central Capacity Sharing models. According to the Central Bottleneck model, dual task interference, as observed in the PRP paradigm, is caused by an all-or-none bottleneck in information processing. The Central Capacity Sharing model postulates that dual task interference is caused by a capacity limited process that can allocate capacity in a graded fashion. The Central Bottleneck model predicts no change in RT1 with decreasing SOA, whereas the Central Capacity Sharing model predicts that RT1 will increase with decreasing SOA and that the slope of the RT1 SOA effect will depend upon the difficulty of task 2. Subjects were required to perform a tone pitch judgement and shape-matching task in rapid succession. Task order was randomized and the SOA between the first and second stimulus varied from 50 to 1250 ms. Results from this experiment favour the Central Capacity Sharing model. The results were then run through simulations of both the Central Bottleneck and Central Capacity Sharing models. Results from the simulations also favoured the Central Capacity Sharing model. As the difficulty of the second task increased, more capacity was allocated to it, confirming the prediction that as task 2 difficulty increases, the RT1 SOA slope increases. The proportion of capacity allocated to the first task varied from.78 to.91 indicating that capacity can be allocated in a graded fashion.

CognitiveTask

PRP

10.1007/s00426-002-0099-0

Psychological research

Psychol Res

Action-based and vision-based selection of input: two sources of control.

In the first part of this paper we review evidence suggesting that there exists a mechanism that selects input on the basis of its similarity to the required action. This response-based input selection differs from the more established space- and object-based input selection in that it is not constrained by the structure of the input. Our evidence suggests that the two-choice Stroop effect is caused by this response-based selection mechanism. By contrast, it is known that the flanker effect is determined by the space- and object- based selection mechanisms. We explore whether the conflict resolution of the Stroop and flanker tasks is different as well by embedding these two tasks in a PRP (Psychological Refractory Period) paradigm. We show that the Stroop and the PRP effects are additive whereas the flanker and the PRP effects are underadditive, suggesting that the processes in charge of the conflict resolution in the Stroop and the flanker tasks are indeed different. We discuss possible reasons for this difference, and discuss possible ways in which the response-based mechanism can be implemented in information processing models.

CognitiveTask

PRP

10.1037//0882-7974.17.3.505

Psychology and aging

Psychol Aging

Age differences in overlapping-task performance: evidence for efficient parallel processing in older adults.

Two psychological refractory period (PRP) experiments were conducted to examine overlapping processing in younger and older adults. A shape discrimination task (triangle or rectangle) for Task 1 (T1) and a lexical-decision task (word or nonword) for Task 2 (T2) were used. PRP effects, response time for T2 increasing as stimulus onset synchrony (SOA) decreased, were obtained for both age groups. The effect of word frequency on T2 was smaller at the short SOA than at the long SOA, reflecting slack effects, which were larger for older than younger adults in both experiments. These results suggest that older adults can perform lexical access of T2 in parallel with the processing of T1 at least as efficiently as younger adults.

CognitiveTask

PRP

10.1017.S0048577202020449

Psychophysiology

Psychophysiology

The functional significance of ERP effects during mental rotation.

In a parity judgment task, the ERPs at parietal electrode sites become more negative as more mental rotation has to be executed. This article provides a review of the empirical evidence regarding this amplitude modulation. More specifically, experiments are reported that validate both the functional relationship between mental rotation and the amplitude modulation as well as the temporal relationship both in single- and in dual-task situations. Additionally, ERP effects are reported in the psychological refractory period (PRP) paradigm with mental rotation as the second task. Finally, unresolved issues are discussed that, I hope, might stimulate future research.

CognitiveTask

PRP

10.3758/bf03196277

Psychonomic bulletin & review

Psychon Bull Rev

Stimulus-response compatibility and psychological refractory period effects: implications for response selection.

The purpose of this paper was to provide insight into the nature of response selection by reviewing the literature on stimulus-response compatibility (SRC) effects and the psychological refractory period (PRP) effect individually and jointly. The empirical findings and theoretical explanations of SRC effects that have been studied within a single-task context suggest that there are two response-selection routes-automatic activation and intentional translation. In contrast, all major PRP models reviewed in this paper have treated response selection as a single processing stage. In particular, the response-selection bottleneck (RSB) model assumes that the processing of Task 1 and Task 2 comprises two separate streams and that the PRP effect is due to a bottleneck located at response selection. Yet, considerable evidence from studies of SRC in the PRP paradigm shows that the processing of the two tasks is more interactive than is suggested by the RSB model and by most other models of the PRP effect. The major implication drawn from the studies of SRC effects in the PRP context is that response activation is a distinct process from final response selection. Response activation is based on both long-term and short-term task-defined S-R associations and occurs automatically and in parallel for the two tasks. The final response selection is an intentional act required even for highly compatible and practiced tasks and is restricted to processing one task at a time. Investigations of SRC effects and response-selection variables in dual-task contexts should be conducted more systematically because they provide significant insight into the nature of response-selection mechanisms.

CognitiveTask

PRP

10.1037//0096-1523.28.3.695

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Loci of signal probability effects and of the attentional blink bottleneck.

To investigate the locus of signal probability effects and the influence of stimulus quality on this locus, the authors manipulated probability in Task 2 of a psychological refractory period (PRP) paradigm. The effect was additive with stimulus onset asynchrony (SOA) when the target was not masked but underadditive with decreasing SOA when the target was masked. Even with masking, however, a range of probabilities had effects additive with SOA. The results suggest loci of stimulus probability before the PRP bottleneck as well as at or after the bottleneck. A second issue addressed was the locus of interference in the attentional blink (AB). The AB was larger when the probability of the first of 2 targets was lower. The results lead to the conclusion that one cause of the AB effect is a locus at least as late as the PRP bottleneck.

CognitiveTask

PRP

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Simultaneous dual-task performance reveals parallel response selection after practice.

E. H. Schumacher, T. L. Seymour, J. M. Glass, D. E. Kieras, and D. E. Meyer (2001) reported that dual-task costs are minimal when participants are practiced and give the 2 tasks equal emphasis. The present research examined whether such findings are compatible with the operation of an efficient response selection bottleneck. Participants trained until they were able to perform both tasks simultaneously without interference. Novel stimulus pairs produced no reaction time costs, arguing against the development of compound stimulus-response associations (Experiment 1). Manipulating the relative onsets (Experiments 2 and 4) and durations (Experiments 3 and 4) of response selection processes did not lead to dual-task costs. The results indicate that the 2 tasks did not share a bottleneck after practice.

CognitiveTask

PRP

10.1016/s0301-0511(02)00007-8

Biological psychology

Biol Psychol

Probing the response selection bottleneck with a cardiac measure: individual differences in strategy for a psychological refractory period task.

We examined the coordination of processing streams when two reaction stimuli are presented with minimal temporal separation (the psychological refractory period, PRP, paradigm). We tested the hypothesis that individuals that grouped responses to the two stimuli would schedule response preparation later than those not-grouping their responses would. Performance measures were combined with a cardiac measure interpreted as an index of response inhibition. Forty-two college-aged participants performed an auditory choice task followed in 50, 100 or 400 ms by a visual choice reaction time (RT) task. Performance results replicated prior work. The timing of cardiac inter-beat intervals (IBIs) showed that participants grouping their reactions did appear to delay response preparation; while Non-Groupers promptly initiated response selection for the initial task. These results generally supported the importance of preparation for understanding the coordination of processing streams.

CognitiveTask

PRP

10.1037//0096-1523.28.2.396

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Ideomotor compatibility in the psychological refractory period effect: 29 years of oversimplification.

Four experiments examined whether the psychological refractory period (PRP) effect can be eliminated with ideomotor compatible (IM) but not stimulus-response compatible (SR) tasks, as reported by A. G. Greenwald and H. G. Shulman (1973). Their tasks were used: a left or right movement to a left- or right-pointing arrow (IM) or to the word left or right (SR) for Task 1; saying "A" or "B" (IM) or "1" or "2" (SR) to an auditory A or B for Task 2. The stimulus onset asynchronies were 0, 100, 200, 300, 500, and 1,000 ms in Experiment 1, and only 0, 100, 200, and 1,000 ms in Experiments 2-4. The arrow was in the center of the screen in Experiments 1-3 and to the left or right in Experiment 4. As in Greenwald and Shulman's Experiment 2, the instructions stated that most often the 2 stimuli would be presented simultaneously. A PRP effect was obtained in all conditions, most likely because response-selection decisions are required even for IM tasks.

CognitiveTask

PRP

10.1068/p3304

Perception

Perception

Separating perception time from response time: the slope transition paradigm.

This paper describes the slope transition paradigm (STP), a variant of rapid serial visual presentation (RSVP) that separates early (perceptual) processing time from total response time. The paradigm is based on a very simple idea: provide varying amounts of time for perceptual processing and find the moment when the subject begins to waste time waiting for more data. That moment is a measure of how much time was actually needed. The method was used in two experiments. Results are discussed in relation to set-size effects, perceptual capacity limits, attentional dwell times, and some related neurophysiological findings. The method appears to tap aspects of information processing that differ from those tapped in studies of the psychological refractory period, the attentional blink, and repetition blindness.

CognitiveTask

PRP

10.1037/h0087381

Canadian journal of experimental psychology = Revue canadienne de psychologie experimentale

Can J Exp Psychol

Does size rescaling require central attention?

The goal of the present experiment was to determine if object size rescaling in the shape-matching task requires central resources. Two polygons were presented side by side as the second task in a psychological refractory period paradigm. The polygons could be the same as each other or mirror images of each other and the size ratio between the two polygons was varied. In the first task, subjects were required to make a speeded response to the pitch of a tone. The polygon task followed at varying SOAs and the subjects then made a speeded same/mirror image judgement on the polygons. The size ratio effect was additive with SOA indicating that size rescaling is capacity demanding and that it requires central attention.

CognitiveTask

PRP

10.1006/cogp.2001.0762

Cognitive psychology

Cogn Psychol

Separate and shared sources of dual-task cost in stimulus identification and response selection.

There is often strong interference if a second target stimulus (T2) is presented before processing of a prior target stimulus (T1) is complete. In the "Psychological Refractory Period" (PRP) paradigm, responses are speeded and interference manifests as increased response time for T2. In the "Attentional Blink" (AB) paradigm, stimuli are masked and responses unspeeded; interference manifests as reduced T2 accuracy. While different causes have usually been considered for PRP and AB phenomena, recent evidence has supported a unified account based on a single, shared restriction on concurrent processing. Here we show that a full assessment of separate and shared resource limitations requires direct comparison of hybrid PRP/AB trials with corresponding pure PRP and AB cases. Randomizing trial types in such a comparison also brings substantial benefit in addressing possible changes in task preparation or readiness. The data from two such experiments--combining speeded auditory (SA) and unspeeded visual (UV) task events--provide clear evidence for both separate and shared resource limitations. Often interference is strongest for T1 and T2 events of the same type, reflecting predominantly different limitations in SA and UV processing. With modest increases in demand, however, interference between different event types can also be made arbitrarily large, reflecting arbitrarily important shared limitations. For even such simple tasks as these, T--T2 interference reflects a combination of relatively local and relatively global sources.

CognitiveTask

PRP

10.1037/0033-295x.108.4.847

Psychological review

Psychol Rev

Serial modules in parallel: the psychological refractory period and perfect time-sharing.

The authors describe ACT-R/perceptual-motor (ACT-R/PM), an integrated theory of cognition, perception, and action that consists of the ACT-R production system and a set of perceptual-motor modules. Each module (including cognition) is essentially serial, but modules run in parallel with one another. ACT-R/PM can model simple dual tasks such as the psychological refractory period (PRP), including subtle results previously explained with executive process interactive control (EPIC, D. E. Meyer & D. E. Kieras, 1997a). The central difference between the theories is that EPIC's productions can fire in parallel, whereas in ACT-R/PM, they are serial. Results from three PRP-like experiments with more demanding cognitive requirements indicate that cognitive processing for the 2 tasks need not overlap. ACT-R's activation-based retrieval processes are critical in accounting for the timing of these tasks and for explaining the dual-task performance decrement.

CognitiveTask

PRP

10.3758/bf03194437

Perception & psychophysics

Percept Psychophys

Cross-modal attentional deficits in processing tactile stimulation.

In order to substantiate recent theorization on the possible links between the causes of the attentional blink and the psychological refractory period phenomena (e.g., Jolicoeur, 1999a), four experiments are reported in which two target stimuli, T1 and T2, were presented in different modalities at varying stimulus onset asynchronies (SOAs), with each stimulus being associated with a distinct task, Task1 and Task2. In Experiment 1, T1 was a tone, and Task1 was a speeded vocal response based on pitch. T2 was a brief press applied to either of two distal fingerpads, and Task2 was a speeded manual response based on tactile stimulus location. In Experiment 2, the same T1 as that used in Experiment 1 was presented, and in Task1 the subject either made a speeded vocal response based on pitch or ignored T1. T2 was a masked tactile stimulation, and Task2 was an unspeeded manual discrimination of the tactile stimulation location. This Task2 was maintained in Experiments 3 and 4. The auditory T1 was replaced with a white digit embedded in a rapid serial visualization presentation of a stream of black letters, and in Task1 the subject either made an unspeeded decision based on T1 identity or ignored T1. In all the experiments, the results showed an SOA-locked impairment in Task2. As SOA was decreased, reaction times in the speeded Task2 of Experiment 1 increased, and accuracy in the unspeeded Task2 of Experiments 2-4 decreased. The SOA-locked impairment was almost eliminated when T1 could be ignored or was absent. The results are discussed in terms of central processing limitations as the cause of such effects.

CognitiveTask

PRP

10.3758/bf03196170

Psychonomic bulletin & review

Psychon Bull Rev

The dual-task SRT procedure: fine-tuning the timing.

In the standard sequential reaction time study, subjects are presented with a repeating sequence of targets to which they must respond as rapidly as possible. With practice reaction times decrease, suggesting a learned ability to exploit the repeating patterns in the display. In a common variation, a second task is interposed, typically a tone-counting task in which subjects must keep track of the frequency with which particular tones occur. In the canonical experiment, these tones appear at varying times in the interval between the subjects' response to a target and the next target. Data are presented that show that this latter variable (the RSOA, response-secondary stimulus onset asynchrony) actually plays an important but previously hidden role in these experiments. A model based on an extension of the notion of the psychological refractory period is introduced to explain these findings.

CognitiveTask

PRP

Psychology and aging

Psychol Aging

The effects of aging on reaction time in a signal detection task.

The effects of aging on response time are examined in 2 simple signal detection tasks with young and older subjects (age 60 years and older). Older subjects were generally slower than young subjects, and standard Brinley plot analyses of response times showed typical results: slopes greater than 1 and (mostly) negative intercepts. R. Ratcliff, D. Spieler, and G. McKoon (2000) showed that the slopes of Brinley plots measure the relative standard deviations of the distributions of response times for older versus young subjects. Applying R. Ratcliff's (1978) diffusion model to fit the response times, their distributions, and response accuracy, it was found that the larger spread in older subjects' response times and their slowness relative to young subjects comes from a 50-ms slowing of the nondecision components of response time and more from conservative settings of response criteria.

CognitiveTask

PRP

Journal of experimental psychology. Learning, memory, and cognition

J Exp Psychol Learn Mem Cogn

Interference from related items in object identification.

Interference between related items in the identification of objects was examined using a postcue procedure. Pairs of objects were presented as differently colored line drawings followed by a color cue to indicate which object to name. Naming latencies were longer when both objects were from the same superordinate category than when they were unrelated. This interference effect was replicated when subjects were cued to report the color of a drawing rather than its name. Interference was greatly reduced when more distinctive attributes were used to distinguish members of a pair, both when the task required naming an object and when it required report of an object's attribute. These results challenge accounts of interference in the postcue paradigm that are based on competitive interactions in the activation of phonological representations by semantics and instead implicate object-attribute integration in memory as the source of interference.

CognitiveTask

PRP

Journal of experimental psychology. Learning, memory, and cognition

J Exp Psychol Learn Mem Cogn

Parallel memory retrieval in dual-task situations: II. Episodic memory.

Three experiments asked whether subjects could retrieve information from a 2nd stimulus while they retrieved information from a 1st stimulus. Subjects performed recognition judgments on each of 2 words that followed each other by 0, 250, and 1,000 ms (Experiment 1) or 0 and 300 ms (Experiments 2 and 3). In each experiment, reaction time to both stimuli was faster when the 2 stimuli were both targets (on the study list) or both lures (not on the study list) than when 1 was a target and the other was a lure. Each experiment found priming from the 2nd stimulus to the 1st when both stimuli were targets. Reaction time to the 1st stimulus was faster when the 2 targets came from the same memory structure at study (columns in Experiment 1; pairs in Experiment 2; sentences in Experiment 3) than when they came from different structures. This priming is inconsistent with discrete serial retrieval and consistent with parallel retrieval.

CognitiveTask

PRP

Journal of experimental psychology. Learning, memory, and cognition

J Exp Psychol Learn Mem Cogn

On attentional control as a source of residual shift costs: evidence from two-component task shifts.

It is widely assumed that supervisory or attentional control plays a role only in the preparatory reconfiguration of the mental system in task shifting. The well-known fact that residual shift costs are still present even after extensive preparation is usually attributed to passive mechanisms such as cross talk. The authors question this view and suggest that attentional control is also responsible for residual shift costs. The authors hypothesize that, under shift conditions, tasks are executed in a controlled mode to guarantee reliable performance. Consequently, the control of 2 task components should require more resources than the control of only 1. A series of 4 experiments with 2-component tasks was conducted to test this hypothesis. As expected, more residual shift costs were observed when 2 components rather than 1 varied across trials. Interference effects and sequential effects could not account for these results.

CognitiveTask

PRP

10.1111/1467-9280.00318

Psychological science

Psychol Sci

Virtually perfect time sharing in dual-task performance: uncorking the central cognitive bottleneck.

A fundamental issue for psychological science concerns the extent to which people can simultaneously perform two perceptual-motor tasks. Some theorists have hypothesized that such dual-task performance is severely and persistently constrained by a central cognitive "bottle-neck," whereas others have hypothesized that skilled procedural decision making and response selection for two or more tasks can proceed at the same time under adaptive executive control. The three experiments reported here support this latter hypothesis. Their results show that after relatively modest amounts of practice, at least some participants achieve virtually perfect time sharing in the dual-task performance of basic choice reaction tasks. The results also show that observed interference between tasks can be modulated by instructions about differential task priorities and personal preferences for daring (concurrent) or cautious (successive) scheduling of tasks. Given this outcome, future research should investigate exactly when and how such sophisticated skills in dual-task performance are acquired.

CognitiveTask

PRP

10.3758/bf03195748

Memory & cognition

Mem Cognit

Naming the color of a word: is it responses or task sets that compete?

Subjects named the colors in which high- and low-frequency words and pronounceable nonwords, otherwise matched, were displayed. Color naming was slower for all three item types than for visually equivalent strings of nonalphanumeric symbols but was no slower for words than for nonwords, nor for high-frequency words than for low-frequency words. Unpronounceable letter strings had intermediate color-naming latencies. However, frequency and lexical status had large effects on latency for reading the same words and pseudowords aloud. Interference is thus predicted not by the strength of association between a letter string and its pronunciation but by the presence of word-like constituents. We argue that the interference from an unprimed noncolor word is due to, and isolates, one of two components of the classic Stroop effect: competition from the whole task set of reading. The other component, response competition, occurs only when lexical access is sufficiently primed.

CognitiveTask

PRP

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Why practice reduces dual-task interference.

M. A. Van Selst, E. Ruthruff, and J. C. Johnston (1999) found that practice dramatically reduced dual-task interference in a Psychological Refractory Period (PRP) paradigm with 1 vocal response and 1 manual response. Results from 3 further experiments using the highly trained participants of M. A. Van Selst et al. (1999) support 4 main conclusions: (a) A processing bottleneck exists even after extensive practice; (b) the principal cause of the reduction in PRP interference with practice is shortening of Task 1 bottleneck stages; (c) a secondary cause is that 1 or more, but not all, of the Task 2 substages that are postponed before practice are not postponed after practice (i.e., become automatized); and (d) the extent of PRP reduction with practice depends on the modalities of the 2 responses. A control experiment with 2 manual response tasks showed less PRP reduction with practice than that found by Van Selst et al.

CognitiveTask

PRP

10.1007/s002210000586

Experimental brain research

Exp Brain Res

Selective effect of closed-head injury on central resource allocation: evidence from dual-task performance.

Two dual-task experiments are reported bearing on the issue of slower processing time for severe chronic closed-head injury (CHI) patients compared to matched controls. In the first experiment, a classical psychological refractory period (PRP) paradigm was employed, in which two sequential stimuli, a pure tone and a colored dot, were presented at variable stimulus onset asynchronies (SOAs), each associated with a distinct task. The task on the tone required a speeded vocal response based on pitch, and the task on the colored dot required a speeded manual response based on color. In the second experiment, either one or three masked letters was presented, followed by a pure tone at variable SOAs. The task on the letters required a delayed report of the letters at the end of each trial. The task on the tone required an immediate manual response based on pitch. In both experiments, both CHI patients and matched controls reported an SOA-locked slowing of the speeded response to the second stimulus, a PRP effect. The PRP effect was more substantial for CHI patients than for matched controls, suggesting that a component of the slower processing time for CHI patients was related to a selective increase in temporal demands for central processing of the stimuli.

CognitiveTask

PRP

10.2466/pms.2000.91.3.893

Perceptual and motor skills

Percept Mot Skills

The psychological refractory period in Parkinson's disease.

The Psychological Refractory Period paradigm was used to investigate whether patients with Parkinson's disease showed disproportional deficits in regulating responses to two sequential presented stimuli. The first task required a speeded key-press response to an auditory stimulus, and the second task required a speeded key-press response to a visual stimulus. The stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 50 msec., 150 msec., and 650 msec. According to the bottleneck model, the SOA manipulation should not affect performance on Task 1, but reaction time for Task 2 should increase as the SOA between the two tasks decreased. The increase in reaction time for Task 2 was referred to as the Psychological Refractory Period. In this study, both patients with Parkinson's disease and normal controls showed classical effects. More importantly, although the 22 patients with Parkinison's disease took longer to respond to both Tasks 1 and 2 than the 20 normal controls, the effects of the Psychological Refractory Period for the two groups were of the same magnitude. The results suggest that Parkinson's disease affects only the response-execution stages rather than the response-selection stages, based on the central bottleneck model.

CognitiveTask

PRP

10.1037//0882-7974.15.4.571

Psychology and aging

Psychol Aging

Aging and the psychological refractory period: task-coordination strategies in young and old adults.

The apparently deleterious effect of aging on dual-task performance is well established, but there is little agreement about the source of this effect. Studies of the psychological refractory period (PRP) indicate that young adults can flexibly control dual-task performance through task-coordination strategies. Thus, the performance of older adults might differ from young adults because older adults use different task-coordination strategies. To test this hypothesis, the executive-process interactive control (EPIC) architecture was applied to quantify the reaction time data from two PRP experiments conducted with young (age 18-26) and older (age 60-70) adults. The results show that participants' ability to coordinate the processing of two tasks did not decline with age. However, dual-task time costs were greater in the older adults. Three sources for this increase were found: generalized slowing, process-specific slowing, and the use of more cautious task-coordination strategies by the older adults.

CognitiveTask

PRP

10.1023/a:1005127504982

Journal of abnormal child psychology

J Abnorm Child Psychol

Does the Conners' Continuous Performance Test aid in ADHD diagnosis?

The performance of clinic-referred children aged 6-11 (N = 100) was examined using the Conners' Continuous Performance Test (CPT) and measures of auditory attention (Auditory Continuous Performance Test; ACPT), phonological awareness, visual processing speed, and visual-motor competence. The Conners' CPT overall index was unrelated to measures of visual processing speed or visual-motor competence. Although the Conners' CPT converged with the ACPT, the latter demonstrated age and order effects. Significant variance in Conners' CPT parameters was predicted by phonological awareness measures, suggesting that Reading Disordered (RD) children could be "false positives" on the Conners' CPT. The Conners' CPT overall index, phonological awareness, and visual-motor measures were submitted to a 2 x 2 MANCOVA (ADHD vs. RD, covarying for age and socioeconomic status): a main effect for RD status was found. Children with ADHD did not have higher Conners' CPT scores than did clinical controls; however, children with Reading Disorders did. Phonological measures distinguished RD children from ADHD children and other clinical controls. ADHD children who failed the Conners' CPT were rated by teachers as more hyperactive. Despite the strengths of the Conners' CPT, its utility for differential diagnosis of ADHD is questioned.

CognitiveTask

PRP

10.1016/s0166-4328(00)00279-5

Behavioural brain research

Behav Brain Res

Reduction of latent inhibition by D-amphetamine in a conditioned suppression paradigm in humans.

The sensitivity of latent inhibition (LI) to amphetamine has been tested in humans with a paradigm close to the conditioned emotional response suppression currently used in experimental animals. The conditioned stimulus (CS) was a tone, the unconditioned stimulus (US) a strong white noise, and the response a transient delay in a regular sequence of hand movements in the resolution of the Tower of Toronto puzzle. The aim of this study was to verify whether the previously reported, disruptive effect of CS preexposure on conditioning really represents LI, by examining its sensitivity to amphetamine. Three groups of healthy volunteers received placebo, 5 or 10 mg of dexamphetamine sulphate, respectively, in a double-blind experimental design. The preexposure, conditioning and test phases were carried out under either amphetamine or placebo. The non preexposed groups treated with amphetamine were not different from the non preexposed placebo group, indicating that amphetamine did not affect conditioning. Among the preexposed groups, those receiving 10 mg of amphetamine showed normal rates of conditioning, whereas those treated with either 5 mg of amphetamine or placebo showed LI. Similar results have been reported in experimental animals. This sensitivity to amphetamine suggests that the present paradigm may be used to study LI in humans.

CognitiveTask

PRP

10.1016/s0166-4328(00)00280-1

Behavioural brain research

Behav Brain Res

Associative learning and latent inhibition in a conditioned suppression paradigm in humans.

A paradigm based on conditioned suppression of ongoing motor activity, sensitive to latent inhibition (LI), was developed and tested in healthy volunteers. Subjects were trained to move disks from one peg to another with a high degree of regularity in the Tower of Toronto puzzle, a well-known cognitive skill learning task. Once this was achieved, they were submitted to a Pavlovian conditioning procedure. The conditioned stimulus (CS) was a pure tone and the unconditioned stimulus (US) a loud white noise. The resulting response suppression was assessed by a transient increase in latency of the hand movements. In control subjects, there was non-contingent CS and US presentation. The results evidenced conditioning after a single CS-US pairing. Following five preexposures to the to-be-conditioned CS, however, conditioning was abolished, seemingly expressing LI. Because a weak unconditioned response to the tone was observed after its first two presentations, an additional experiment was performed with two preexposures to the to-be-conditioned CS. With such procedure, conditioning was obtained, supporting the existence of LI in the preceding experiment. These results indicate that the present paradigm may be useful for the study of LI in human subjects, having the advantage of being similar to the experimental conditions used in the majority of LI studies in experimental animals.

CognitiveTask

PRP

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

A dual-task investigation of automaticity in visual word processing.

An analysis of activation models of visual word processing suggests that frequency-sensitive forms of lexical processing should proceed normally while unattended. This hypothesis was tested by having participants perform a speeded pitch discrimination task followed by lexical decisions or word naming. As the stimulus onset asynchrony between the tasks was reduced, lexical-decision and naming latencies increased dramatically. Word-frequency effects were additive with the increase, indicating that frequency-sensitive processing was subject to postponement while attention was devoted to the other task. Either (a) the same neural hardware shares responsibility for lexical processing and central stages of choice reaction time task processing and cannot perform both computations simultaneously, or (b) lexical processing is blocked in order to optimize performance on the pitch discrimination task. Either way, word processing is not as automatic as activation models suggest.

CognitiveTask

PRP

10.1037//0096-1523.26.4.1260

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Multiple spatial correspondence effects on dual-task performance.

Three dual-task experiments were conducted to examine whether the underadditive interaction of the Simon effect and stimulus onset asynchrony (SOA) on Task 2 performance is due to decay. The experiments tested whether the reverse Simon effect obtained with an incompatible stimulus-response (S-R) mapping would show an overadditive interaction with SOA, as predicted by R. De Jong, C.-C. Liang, and E. Lauber's (1994) dual-process model. Tone or letter identification tasks with vocal or keypress responses were used as Task 1. Task 2 was keypresses to arrow direction (or letter identity in Experiment 1). For all experiments, the normal Simon effect showed an underadditive interaction with SOA, but the reverse Simon effect did not show an overadditive interaction. The results imply that the dual-process model is not applicable to the dual-task context. Multiple correspondence effects across tasks implicate an explanation in terms of automatic S-R translation.

CognitiveTask

PRP

10.3758/bf03212993

Psychonomic bulletin & review

Psychon Bull Rev

Direct versus indirect tests of memory: directed forgetting meets the generation effect.

Subjects read 20 words and generated 20 others from definitions during a 40-item study phase. Production of each word was followed by an instruction to remember or to forget that word. In free recall, a direct test of memory, words that had been generated were recalled much better than words that had been read. The remember-forget instructional manipulation affected read words but not generated words. In speeded word reading, an indirect test of memory, all studied words showed priming, but read words showed more priming than generated words. Here, the effect of remember versus forget instructions appeared only for generated words. These dissociations of a direct and an indirect test indicate that two powerful encoding manipulations affect separable processes to which these tests are differentially sensitive.

CognitiveTask

PRP

10.1037//0096-1523.26.3.1091

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Specification of movement amplitudes for the left and right hands: evidence for transient parametric coupling from overlapping-task performance.

Bimanual coordination tasks suggest transient cross-talk between concurrent specification processes for movements of the left and right hand that vanishes as the time for specification increases. In 2 experiments with overlapping and successive unimanual tasks, the hypothesis of transient coupling was examined for a psychological-refractory-period paradigm. Time for specification was manipulated by varying the delay between first and second signal (Experiment 1) and by precuing the first response (Experiment 2). Participants performed rapid reversal movements of same or different amplitudes with the left and right hands. With different amplitudes, reaction times (RTs) of the second responses were longer than with same amplitudes at short delays, and this disappeared at longer delays in Experiment 1. In Experiment 2, precuing also reduced the difference between RTs of second responses in same-amplitude and different-amplitude trials. These findings are consistent with the hypothesis of transient coupling during amplitude specification obtained with bimanual tasks.

CognitiveTask

PRP

10.1037//0096-1523.26.2.568

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

The combined effects of plane disorientation and foreshortening on picture naming: one manipulation or two?

Objects disoriented in plane away from the upright and objects rotated in depth producing foreshortening are harder to identify than canonical views. In Experiments 1 and 2, participants named pictures of familiar objects. There was no interaction between plane and depth rotation effects on initial presentation or after practice. Experiment 3 was a dual-task psychological refractory period study. Participants classified a high-low tone with a speeded keypress and then named a canonical, plane-rotated, or foreshortened view of an object. Naming was slower when the picture was presented 50 ms after the tone compared with 800 ms after the tone. Plane rotation effects were reduced (but not eliminated) at the short tone-picture stimulus onset asynchrony, but foreshortening effects were not reduced. The results implicate an early, prebottleneck locus for some processes compensating for plane rotation and a subsequent bottleneck or postbottleneck locus for compensation for foreshortening.

CognitiveTask

PRP

10.1017/s1355617700611062

Journal of the International Neuropsychological Society : JINS

J Int Neuropsychol Soc

Elucidating the contributions of processing speed, executive ability, and frontal lobe volume to normal age-related differences in fluid intelligence.

One theory of normal cognitive aging asserts that decreases in simple processing speed mediate the age-related decline of fluid intelligence. Another possibility is that age-related atrophic changes in frontal brain structures undermine the functioning of executive abilities, thereby producing the same decline. In this study, we used principal components analysis to derive a measure of fluid-spatial intelligence in 197 normal adults between 20 and 92 years of age. Measures of perceptual comparison speed, working memory, and executive ability, as well as regional brain volumes based on high resolution magnetic resonance imaging were obtained from a subsample of 112 participants. We then conducted a series of hierarchical multiple regression analyses to test whether (1) the processing speed theory, (2) frontal-executive theory, or (3) some combination of these best accounted for age-related variation in fluid intelligence. The results showed that perceptual comparison speed, executive ability, and frontal lobe volume each made significant contributions to a regression equation that explained 57% of the variance in fluid intelligence. These findings suggest that both the processing speed and frontal-executive theory of cognitive aging are partially correct and complement one another.

CognitiveTask

PRP

10.1006/brcg.1999.1082

Brain and cognition

Brain Cogn

Attentional inhibition or paracontrast?

In visual search experiments using asynchronous presentation of target and distractors, a robust and unexpected inhibition of reaction time was observed for the discrimination of a temporally trailing target. A number of experiments were required to determine the source of this inhibition. These experiments eliminated the possibilities that the inhibition might be a manifestation of three attentional processes: inhibition of return, attentional dwell time, or attentional capture by the temporally leading item. Other experiments eliminated the possible preattentional process of the temporal impulse response, the psychological refractory period, and a response inhibition. The characteristics of this inhibition lead to the conclusion that it is a manifestation of paracontrast.

CognitiveTask

PRP

10.1037//0096-1523.25.5.1268

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Can practice eliminate the psychological refractory period effect?

Can people learn to perform two tasks at the same time without interference? To answer this question, the authors trained 6 participants for 36 sessions in a Psychological Refractory Period (PRP) experiment, where Task 1 required a speeded vocal response to an auditory stimulus and Task 2 required a speeded manual response to a visual stimulus. The large PRP effect found initially (353 ms in Session 1) shrank to only about 40 ms over the course of practice, disappearing entirely for 1 of the 6 participants. This reduction in the PRP effect with practice is considerably larger than has been previously reported. The obtained pattern of factor interactions between stimulus onset asynchrony and each of three task difficulty manipulations (Task 1 judgment difficulty, Task 2 stimulus contrast, and Task 2 mapping compatibility) supports a postponement (bottleneck) account of dual-task interference, both before and after practice.

CognitiveTask

PRP

Neuropsychiatry, neuropsychology, and behavioral neurology

Neuropsychiatry Neuropsychol Behav Neurol

Neurophysiologic mechanisms of attention deficits in schizophrenia.

Despite advances in the pharmacologic treatment of schizophrenia, the neurophysiologic mechanism(s) of disordered attention in schizophrenia remain elusive. The goal of the present study was to assess specific components of attention, including disengagement, movement, re-engagement, and the inhibitory processes involved their control. Thirteen chronic schizophrenics from the inpatient and outpatient units of the Veterans Administration Medical Center (New Orleans, LA) and thirteen normal control subjects were administered a saccadic eye movements task. Saccade latency was measured in the presence of contra-lateral distracter stimuli that preceded the target onset (Distracter-before), followed the target onset (Distracter - after) or in the absence of a distracter (No-distracter). In order to assess the interactive process of fixation disengagement and target selection, fixation was either offset before the target (Gap) or it remained on in the presence of the target (Overlap). Repeated measures analysis of variance revealed that saccadic latency in patients with schizophrenia is prolonged to a greater extent than in normal control subjects in the presence of distracter stimuli. Patients with schizophrenia are also characterized by a greater percentage of error saccades directed to the distracter, and require a longer latency to "issue" corrective saccades following error saccades. The findings suggest that patients with schizophrenia are required to invoke volitional control under distracter conditions, whereas normal control subjects require minimal volitional control. The results are interpreted in terms of the inhibitory mechanisms that regulate attention.

CognitiveTask

PRP

10.1046/j.1440-1606.1999.00184.x

Australian and New Zealand journal of ophthalmology

Aust N Z J Ophthalmol

Temporal limitations of information processing in global and local attention: the effect of information content.

The refractory period during which detection or identification of a probe is degraded, following the successful visual identification of a target, is referred to as the attentional blink (AB). Previous work in this laboratory using global/local letter forms has shown that the degree of complexity of information influences the length of time between successful visual identifications, as does the attentional modality required of the subject. In the standard rapid serial visual presentation (RSVP) task, a gap following the first target is reported to destroy the AB. The current study examines the effect on the AB duration of inserting a gap in the stream of local orthographic information while not interrupting the stream of global information. It was hypothesized that masking of the local elements of the item immediately following the target (the +1 item) would lead to a decreased AB duration for local identification. Twenty-one adult participants, experienced in the experimental paradigm, viewed sequences of compound letter stimuli and were required to identify a global or local red letter (target) and detect the presence of a global or local X (probe) in the sequence following. In one-half of the trials the local letter identity of the +1 global/local form was obscured, leaving only a global form. Neither the attentional condition nor local +1 masking significantly influenced the slope of recovery from the AB. Furthermore, no difference was observed in the AB duration for global or local probe detection between control and crystallized trials. The results suggest that the visual image of the item is accepted nto VSTM and processed for target candidature.

CognitiveTask

PRP

10.1007/s004260050039

Psychological research

Psychol Res

Mental rotation, memory scanning, and the central bottleneck.

Two reaction-time experiments using the psychological refractory period paradigm examined whether two prominent tasks, i.e., mental rotation and memory scanning, require access to a single-channel mechanism and must therefore be performed sequentially with other operations requiring the same mechanism. On each trial, subjects made speeded responses to a tone (Exp. 1) or a character (Exp. 2, with symbolic SR-compatibility of the character manipulated) as Task 1 and to a letter (for blocks with mental rotation) or a digit (for blocks with memory scanning) as Task 2. The set-size effect was constant across SOAs, suggesting that memory scanning cannot be performed in parallel with response selection of Task 1. The effect of orientation, however, decreased with decreasing SOA. The decrease was even intensified if Task 1 bottleneck processes were prolonged by symbolic SR-compatibility. The exact pattern of underadditivity, however, was not predicted by current theories of dual-task performance. The results contradict a central bottleneck model but are in line with extensions of the model proposed by Meyer and Kieras.

CognitiveTask

PRP

10.1177/026988119801200402

Journal of psychopharmacology (Oxford, England)

J Psychopharmacol

Repeated testing of prepulse inhibition and habituation of the startle reflex: a study in healthy human controls.

The aim of this study was to examine the effect of repeated testing on prepulse inhibition (PPI) and habituation of the startle reflex. Fifteen healthy control subjects (eight males, mean age 30 years; seven females, mean age 29 years) were tested on three occasions across the same day separated by a minimum of 2 h. An acoustic probe of 40-msec bursts of 116 dB(A) white noise over a continuous background noise of 70 dB(A) was presented binaurally through headphones and the eye-blink component of the startle response was measured taking electromyographic recordings from the right orbicularis oculi. The test session was identical at each time point and consisted of two blocks of 12 randomly mixed trials of four pulse-alone, four 60-msec prepulse and four 120-msec prepulse trials enclosed by two blocks each of six pulse-alone trials. There was huge variation in individual response magnitude that was independent of subsequent PPI in both women and men. Women showed greater PPI in the second half of sessions with the 120-msec prepulse only; but PPI was not altered significantly in either group between sessions across the day. In general, there was good test-retest reliability of PPI especially within trial type. Normal reflex habituation occurred across sessions and this effect was preserved in sessions across the day. Latency of response was significantly reduced in a session by the 60-msec trial type compared to the 120-msec trial type, as previously reported. Our results suggest that measures of PPI and habituation of the startle response are appropriate and reliable for a within-subject, test-retest design.

CognitiveTask

PRP

10.3758/bf03201181

Memory & cognition

Mem Cognit

Differential components of the manual and vocal Stroop tasks.

In this study, four components of the Stroop effect were examined for manual word and vocal responses. The components were lexical, semantic relatedness, semantic relevance, and response set membership. The results showed that all four components were present in the vocal response task. However, in the manual word response task, the only component that produced significant interference on its own was response set membership. These results do not support predictions made by recent translation models (see W. R. Glaser & M. O. Glaser [1989] and Sugg & McDonald [1994]). A possible solution was suggested that located two sites for Stroop interference. The lexical, semantic relatedness, and semantic relevance effects were located in the lexical system, whereas the response set membership effect was located at a response selection stage.

CognitiveTask

PRP

10.3758/bf03201180

Memory & cognition

Mem Cognit

Modulation of the attentional blink by on-line response selection: evidence from speeded and unspeeded task1 decisions.

Two critical target stimuli (T1 and T2) were embedded in a stream of white letters shown on a black background, using a rapid serial visual presentation paradigm (RSVP, 100 msec/item). T1 was a red H or S; T2 was an X or a Y. Performance in a two-alternative discrimination on T2 was impaired when processing of T1 was required--a result often called an attentional blink (AB). In previous work, the response in Task1 has been an unspeeded and delayed response at the end of the trial. Three experiments compared performances in Task2 that depended on whether Task1 required an unspeeded delayed response or a speeded immediate response. A larger AB was found when a speeded response was required. Furthermore, in the speeded conditions, faster responses in Task1 were associated with a smaller and shorter AB effect than were slower responses. The results show that manipulations affecting a relatively late stage of processing--response selection--affect the magnitude and duration of the AB phenomenon. A new central inhibition theory is proposed to account for these results. According to this theory, the AB is similar to the psychological refractory period effect and is caused by central postponement of short-term consolidation of T2.

CognitiveTask

PRP

10.1037//0882-7974.13.2.218

Psychology and aging

Psychol Aging

The psychological refractory period: evidence for age differences in attentional time-sharing.

The authors report 2 psychological refractory period (PRP) experiments in which the stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 150 ms, 250 ms, 600 ms, and 1,100 ms for both younger and older adults. H. Pashler's (1994a) response-selection bottleneck theory predicts that SOA manipulations should not affect Task 1 performance, but that reaction time (RT) for Task 2 should increase as the SOA between the 2 tasks decreases (i.e., the classical PRP effect). In Experiment 1 (Task 1 = tone discrimination, Task 2 = dot location), older adults showed a larger PRP effect than younger adults did, although Task 1 RT was affected by SOA, suggesting that participants were grouping their responses on some trials. That is, participants were holding their response for Task 1 until they had completed processing Task 2, and then they responded to both tasks almost simultaneously. However, a subset of participants (11 younger adults and 11 older adults) who showed no evidence of response grouping on Task 1 continued to show a larger PRP effect for older adults on Task 2. In Experiment 2 (Task 1 = dot location, Task 2 = simultaneous letter matching), older adults continued to show a larger PRP effect than younger adults for Task 2, and Task 1 performance was unaffected by SOA. Consequently, these experiments provide evidence that older adults (relative to younger adults) exhibit a decrement in time-sharing at the response-selection stage of processing. These results suggest that attentional time-sharing needs to be added to the list of topics examined in aging research on varieties of attention.

CognitiveTask

PRP

10.1037//0096-1523.24.2.463

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

The psychological refractory period effect following callosotomy: uncoupling of lateralized response codes.

A callosotomy patient was tested in 2 dual-task experiments requiring successive speeded responses to lateralized stimuli. The patient showed a robust psychological refractory period (PRP) effect. Three aspects of the data indicate that, unlike for the control participants, the PRP effect for the split-brain patient should not be attributed to a response selection bottleneck. First, the patient did not show an increase in reaction time (RT) when the 2 tasks required responses from a common output system compared with when different output systems were used. Second, inconsistent stimulus-response mappings for the 2 tasks increased RTs for the control participants but had minimal effect on the performance of the split-brain patient. Third, the consistency manipulation was underadditive with stimulus onset asynchrony but was additive or overadditive for the normal participants. These results suggest that the persistent PRP effect following callosotomy should be attributed to a bottleneck associated with response initiation, a strategy adopted to comply with the task demands, or a combination of these factors.

CognitiveTask

PRP

10.1016/s0031-9384(97)00523-4

Physiology & behavior

Physiol Behav

Influence of male-related stimuli on female postejaculatory refractory period in rats.

Female rats "pace" their sexual contacts with the male when tested in situations where they can escape from the male during copulation. The type and quality of vaginocervical stimulation that the females receive during copulation influences their pacing behavior. This study investigated the effect of several male-related stimuli on the female's postejaculatory refractory period (PER). Females were tested in a two-compartment test chamber from which they could escape the male through one of four openings along the bottom of the barrier separating the two compartments. Experiment 1 examined the influence of the seminal plug, the penile cup, and prostate secretions on the female's PER. Results showed that neither the seminal plug, the penile cup, nor prostate secretions contributed to the female's PER. Experiment 2 investigated the relation of pre-ejaculatory intromission frequency, ejaculation duration, and the number of pelvic thrusts during ejaculation to the female's PER. Results indicated that pre-ejaculatory intromission frequency and ejaculation duration but not the number of pelvic thrusts during ejaculation were significantly correlated with the female's PER. In addition, pre-ejaculatory intromission frequency was significantly correlated with ejaculation duration. Partial correlation analysis suggested that pre-ejaculatory intromission frequency affected ejaculation duration which, in turn, influenced the female's PER. This finding was further supported by the evidence that ejaculation duration and the female's PER were significantly shorter in tests in which the male ejaculated on the first or second intromission.

CognitiveTask

PRP

10.2466/pms.1997.85.2.563

Perceptual and motor skills

Percept Mot Skills

Evidence for psychological refractory effect in motor inhibition for a dual-response Go/No-Go task.

Human subjects exhibit difficulty in initiating two independent, discrete responses in close succession, a difficulty known as the 'psychological refractory effect.' It is not yet known whether motor-inhibition processes are under the influence of this effect, as are motor-execution processes. This study examined the temporal changes of subjects' reaction times, interpreted in terms of motor programming for inhibition, in a dual-response Go/No-Go task that required two independent responses in close succession. Eight subjects performed the task with both a shorter (400 msec.) and a longer interstimulus interval (800 msec.). The mean reaction time for the second stimulus (RT2) in the Go response of the 400-msec. condition was significantly longer than that of the 800-msec. condition. For committed error responses during the No-Go trials, the mean RT2 in the 400-msec. condition was longer than that in the 800-msec. condition. The total number of these errors in the 400-msec. condition was significantly greater than that in the 800-msec. condition. These results suggested that both the motor-execution processes and motor-inhibition processes were influenced by the psychological refractory effect.

CognitiveTask

PRP

10.1037//0096-1523.23.3.861

Journal of experimental psychology. Human perception and performance

J Exp Psychol Hum Percept Perform

Blindness to response-compatible stimuli.

This contribution is devoted to the question of whether action-control processes may be demonstrated to influence perception. This influence is predicted from a framework in which stimulus processing and action control are assumed to share common codes, thus possibly interfering with each other. In 5 experiments, a paradigm was used that required a motor action during the presentation of a stimulus. The participants were presented with masked right- or left-pointing arrows shortly before executing an already prepared left or right keypress response. We found that the identification probability of the arrow was reduced when the to-be-executed reaction was compatible with the presented arrow. For example, the perception of a right-pointing arrow was impaired when presented during the execution of a right response as compared with that of a left response. The theoretical implications of this finding as well as its relation to other, seemingly similar phenomena (repetition blindness, inhibition of return, psychological refractory period) are discussed.

CognitiveTask

PRP