bluuebunny/crossref_metadata_2025 huggingface dataset:
Does Aerobic Fitness Affect Sleep?
Authors: Paxton Susan J. , Trinder John , Montgomery Iain
Published: February 2007

Aerobically fit athletes have been shown to have elevated levels of slow wave sleep, greater sleep durations, and shorter sleep onset latencies. However, by using independent group designs, previous studies have potentially confounded aerobic fitness with other characteristics of athletic individuals. In this study the sleep of proficient athletes was assessed on two occasions, initially when they were unfit and subsequently when aerobically fit, and compared with an unfit, non‐athletic, sedentary group. The athletes tended to sleep longer and they had elevated slow wave sleep levels. However, these differences were independent of the aerobic fitness of the athletes. Thus sleep does not vary as a function of aerobic fitness, rather, previously reported differences appear to be a function of more enduring characteristics of athletic individuals.
The Effect of Prolonged Stimulus Repetition on Autonomic Response and EEG Activity in Normal Subjects, Schizophrenic, and Nonschizophrenic Patients
Authors: Bernstein Alvin S. , Taylor Kenneth W. , Starkey Paul , Lubowsky Jack , Juni Samuel , Paley Herbert
Published: February 2007

The effects of prolonged stimulus repetition were studied in 40 schizophrenics, 40 normal controls, and 40 nonschizophrenic patients. 1000‐Hz, 1‐sec tones with 25‐msec rise times were repeated 70 times at 60 or 90 dB while skin conductance (SCR), finger pulse volume (FPV), and EEG were recorded.

Consistent with their hyporesponsiveness in the initial orienting response (OR), schizophrenics displayed less increment in responsiveness with prolonged stimulation, whether in terms of the overextinction (OE) criterion adopted here or of Zahn's post‐habituation response‐rate score. Among the schizophrenics, those with relatively higher post‐habituation response rates showed less emotional withdrawal and greater suspiciousness.

OE was more frequent in FPV than in SCR, Since the reverse was true for initial ORs, it is unlikely that the greater FPV‐OE simply reflects bias due to normal arrhythmias. The major incidence of OE response occurred within a narrow range of trials, similar in SCR and FPV. OE response in SCR (but not in FPV) was accompanied by renewed alpha blockade. SCR‐OE was not related to initial SCR‐OR activity, but the data were less consistent for FPV‐OE, leaving the initial OR‐OE relationship somewhat ambiguous. OE was not associated with evidence of cortical inhibition. Instead, electrodermal OE was preceded by a heightening of skin conductance level suggesting some (limited) role for arousal state. Differences between OE and initial OR were discussed.
P300 Latency and Digit Span
Authors: Surwillo Walter W.
Published: February 2007

The relationship betweeen P300 latency and digit span reported by Polich, Howard, and Starr (1983) is re‐examined. Evidence is presented which shows that these authors' use of partial correlation to correct for age differences in their sample of subjects is erroneous because the assumption of linear regression is clearly not satisfied. This finding seriously questions Polich et al.'s conclusion that P300 latency and digit span covary irrespective of any relationship of the variables to age.
The Endogenous Eyeblink
Authors: Stern John A. , Walrath Larry C. , Goldstein Robert
Published: February 2007

The endogenous eyeblink is identified as a cortically controlled response event, distinguishable from both reflexive and voluntary lid movements. It has a characteristic rate, form, and temporal distribution. These aspects of endogenous blinks are related to cognitive state variables. Allocation of attentional resources, transition points in information processing flow, and possibly processing mode, are indexed by blink parameters.
Cognitive Brain Potential Components in Adolescents
Authors: Friedman David , Brown Charles , Vaughan Herbert G. , Cornblatt Barbara , Erlenmeyer‐Kimling L.
Published: February 2007

Event‐related potentials (ERPs) were recorded in a cross‐sectional study from 70 adolescents ranging in age from 11 to 18. A paradigm was used in which background, standard auditory events (66 percent occurrence) were randomly replaced by either a change in pitch, or a missing stimulus, each occurring 17 percent of the time. Subjects were instructed to respond to one of the infrequent events, with each designated as relevant (i.e., a target) on alternate blocks of trials. Factor score analyses showed that P300 and frontal negative slow wave were larger to relevant than irrelevant events, whereas parietal positive slow wave was not. Both N200 and frontal negative slow wave showed modest age effects. Significant effects of sex, mainly for the exogenous components, were also found. These data highlight the importance of the negative task‐related potentials as correlates of development. They also point to the functional independence of P300 and slow wave and add to the evidence for the functional distinction between the frontal negative and parietal positive aspects of slow wave.
Electrodermal Habituation Speed and Visual Monitoring Performance
Authors: Vossel Gerhard , Rossmann Rainer
Published: February 2007

Previous research has suggested that speed of habituation of the electrodermal orienting response is related to auditory vigilance performance. The present study investigated the relationship between habituation speed, nonspecific response frequency, and detection performance in a complex visual monitoring task. Two levels of task difficulty were employed. In the visual monitoring task, correct detections declined across blocks, and fewer signals were detected in the difficult task condition. Slow habituators detected more signals than fast habituators, but NSR‐frequency was not significantly related to the number of correct detections. The implications of these findings for different models of the relationship between habituation speed and vigilance performance are discussed.
The Effect of Stimulus Significance on Skin Conductance Recovery
Authors: Janes Cynthia L. , Strock Barbara D. , Weeks David G. , Worland Julien
Published: February 2007

The relationship between skin conductance (SC) recovery time and stimulus meaning was investigated. Previous research has shown that a strong relationship between prestimulus electrodermal activity (prior activity) and recovery time makes it necessary to control prior activity before the relationship of recovery time and stimulus meaning can be evaluated properly. In this study prior activity was controlled by experimental design. We examined the effects of stimulus meaning on skin conductance recovery time and amplitude in 55 teenage and young adult subjects in a continuous performance paradigm. Tones were presented monaurally to left and right ears. Subjects were required to make a pedal press after any tone in the left or right ear that followed a right‐ear tone. Recovery time was computed for left‐ear and right‐ear tones not requiring a press because they had been preceded by a left‐ear tone. SC recovery was longer for signal (right‐ear) than for nonsignal (left‐ear) tones with the effects of prior SC activity and amplitude removed. These findings replicate those of a pilot study (Janes, 1982). We conclude that stimulus significance can affect SC recovery time and that in this paradigm differences in prior SC activity cannot account for the recovery time differences observed.
Neonatal Acoustically‐Elicited Cardiac Response: Modulation by State and Antecedent Stimulation
Authors: Ver Hoeve James N. , Leavitt Lewis A.
Published: February 2007

This study investigated modulation of the acoustic cardiac reflex (ACR) in human neonates. Three groups of 16 human neonates born at term were presented an abrupt cardioacceleratory auditory stimulus during awake (AW), quiet sleep (QS), and active sleep (AS) states of wakefulness. On 3/4 of the trials this stimulus was preceded by a continuous pure tone at lead times of either 100, 250, or 4000 ms. Across state, prestimulation modified the amplitude and pattern of the neonatal ACR. Relative to trials without prestimulation, the 100‐ms lead inhibited, whereas the 250‐ms and the 4000‐ms lead stimului enhanced the ACR. During AS, neonates exhibited a triphasic ACR that returned to baseline within 9 s in contrast to the sustained responses in AW and QS states. The results demonstrate central inhibitory and facilatatory control over the ACR early in postnatal life. The pattern of results is consistent with the adult pattern of acoustic startle modulation, as is the absence of significant state effects. Given data from 2‐month‐old infants suggesting an absence of inhibitory effects in acoustic modulation of cardiac startle, it appears that there are non‐linear changes in this basic sensory processing mechanism during the first months after birth.
Electrodermal Discrimination of Familiar and Unfamiliar Faces: A Methodology
Authors: Tranel Dan , Fowles Don C. , Damasio Antonio R.
Published: February 2007

A study is reported which establishes a methodology for investigating the hypothesis that prosopagnosic patients, who have lost the ability to recognize faces, may nonetheless demonstrate electrodermal discrimination of familiar versus unfamiliar facial stimuli. Skin conductance response (SCR) data were recorded while neurologically‐intact, college‐aged subjects viewed slides of 8 famous, highly familiar faces and 42 unfamiliar faces. The results showed that the familiar faces elicited, on the average, much larger SCRs than the unfamiliar faces. In addition, a second group of subjects rated the familiar faces as more “significant” than the unfamiliar ones, and it is concluded that highly familiar faces are potential signal stimuli. Also, because the paradigm involves few instructions and no overt behavioral response by the subject, this methodology could be readily adapted to investigations of prosopagnosic and other brain‐damaged populations in which there is severe amnesia, aphasia, or apraxia.
The Bayesian‐Inferential Approach to Defining Response Processes in Psychophysiology
Authors: O'Connor Kieron
Published: February 2007

The aim is to discuss the potential application of Bayesian inferential methods to the definition and quantification of psychophysiological responses.

Current approaches to response definition and experimental design in psychophysiology usually adopt the view that physiological responses are dependent effects produced by stimulus controlled states or events (which form the independent variables). The statistical model associated with this approach does not fit psychophysiological data and leads to problems in establishing validity and reliability of effects and other measurement problems.

An alternative approach is offered by inferential methods where the response activity is considered independent and the hypotheses are considered dependent variables. This approach frees the psychophysiological data from any statistical assumptions about its form and allows, via use of Bayesian Likelihood estimates, for a precise meaning to be attached to probable response parameters. However, the inferential approach does require adopting a process paradigm where behavioral or cognitive activity is isomorphic with recorded physiological activity.

The inferential approach is particularly useful where a decision on the functional significance of activity is desired over relatively few trials, and seems optimal for ideographic studies where a stable measure of change within a subject over time is required.
Cardiac and Blink Reflex Concomitants of Attentional Selectivity: A Comparison of Adults and Young Children
Authors: Anthony Bruno J. , Putnam Lois E.
Published: February 2007

Selective attention, often considered less efficient in young children, was examined in adults and 5‐yr‐olds using a new, startle‐probe technique. To investigate the allocation of preparatory attention at early stages of processing, we examined the modification of the startle blink reflex to irrelevant acoustic probes presented within the warning interval (WI) of a simple reaction time task. Attention was directed away from the acoustic probes and toward a vibrotactile GO signal during the 6‐s WI. Heart rate decelerated prior to the GO signal in both children and adults, implying increased attention. The two groups showed opposite patterns of blink modification, however. In adults, startle blink to the WI probes was increasingly attenuated as the GO signal approached, suggesting a selective pattern of attentional allocation. In contrast, blink amplitude increased linearly across probe positions in children, implying that preparatory attention was allocated to a wider range of sensory input.
Detection of Averaged Heart Rate Response to Tones in Human Newborns
Authors: Crowell David H. , Kapunial Linda E. , Jones Richard H.
Published: February 2007

Response criteria for a significant averaged evoked heart rate response to 63 and 80 dB SPL tones at 500, 1000, 2000, 4000, 6000, and 8000 Hz were objectively defined by means of autoregressive analysis in 25 newborns (Group I). This statistical procedure for detecting significant heart rate (HR) change was based on predictions derived from heart rate activity occurring prior to onset of a stimulus. The Group I criteria were applied to HR responses of 65 newborns (Group II) averaged over 2 to 24 trials. Averaged HR changes were low for 2 trials but increasingly higher when based on the average over all 63dB SPL tones, all 80dB SPL tones, and finally, all tones; 43, 65, and 77 percent of the infants responded, respectively. For the last three conditions, the averages were based on 12, 12, and 24 trials, respectively. Results suggest that in human newborns the averaged HR response may (a) function as a reliable auditory response measure, (b) supplement other measures of neonatal responsivity to suprathreshold tones, (c) provide information on early auditory abilities and the developmental course of auditory functioning, and (d) serve as a technique for investigating cardiac orienting and the effects of behavioral teratogens on auditory functioning.
The Relation Between Rhythmic Cardiovascular Variability and Reactivity to Orthostatic, Cognitive, and Cold Pressor Stress
Authors: Hatch John P. , Klatt Keith , Porges Stephen W. , Schroeder‐Jasheway Lori , Supik Josie D.
Published: February 2007

Two groups of normotensive, male subjects having either a positive or negative parental history of essential hypertension were exposed to passive body tilt from horizontal to a 70° head‐up posture, while systolic and diastolic blood pressure, heart period, and respiration amplitude were sampled on a beat‐by‐beat basis. Subjects also performed mental arithmetic and cold pressor tasks, and cardiovascular reactivity was expressed as change from baseline levels. The body tilt data were analyzed by cross‐spectral analysis focusing on two frequency bands, one between .06‐.1 Hz, and the other at the predominant breathing frequency. The two groups did not differ significantly in their basal levels of physiological activity or in their response to the tasks. Cross‐spectral analysis identified tilt induced changes in the power spectra and coherence spectra within the two frequency bands. These changes differed between the two frequency bands and among the various physiological response systems investigated. Larger rhythmic oscillations in heart period within both frequency bands predicted greater cardiovascular reactivity to the mental arithmetic task but not the cold pressor task. The results are discussed in terms of neural control mechanisms (e.g., vagal tone) implicated in the dynamic regulation of cardiovascular function during psychophysiological states such as stress.
Face the Beast and Fear the Face: Animal and Social Fears as Prototypes for Evolutionary Analyses of Emotion
Authors: ÖHman Arne
Published: February 2007

This paper applies a functional‐evolutionary perspective to fear in the context of encounters with animals and threatening humans. It is argued that animal fear originates in a predatory defense system whose function is to allow animals to avoid and escape predators. Animal stimuli are postulated to be differentially prepared to become learned elicitors of fear within this system. Social fears are viewed as originating in a dominance/submissiveness system. The function of submissiveness is to avert attacks from dominating conspecifics. Signs of dominance paired with aversive outcomes provide for learning fear to specific individuals. Data which in general are interpreted as supportive of this conceptualization are reviewed. To explain the mechanism behind the causal relationships suggested in the evolutionary analysis, an information‐processing model is presented and empirically tested. It is argued that responses to evolutionary fear‐relevant stimuli can elicit the physiological concomitants of fear after only a very quick, “unconsciousness,’ or preattentive stimulus analysis. Support for this notion is presented from backward masking studies where it is demonstrated that conditioned autonomic responses to fear‐relevant stimuli can be elicited even with masked stimuli.
Event‐Related Potentials in Chronometric Analysis of Primed Word Recognition with Different Stimulus Onset Asynchronies
Authors: Boddy John
Published: February 2007

In a lexical decision experiment in which primes preceded associatively related words, unrelated words, or non‐words, N1(154 ms)‐P2(245 ms), P2, and P3 (502 ms) increased in amplitude with increasing semantic association, while N2 (340 ms) amplitude, as well as response times, showed an opposite relationship and increased with decreasing semantic association. The relationship, in each case, persisted across a range of stimulus onset asynchronies (SOAs: onset‐to‐onset) from 1000 down to 200 ms.

Despite the apparent dissociation of P2 and N2, it could not be unequivocally established that they reflected successive discrete phases of processing. The balance of evidence indicated that the variation of both P2 and N2 across conditions could be attributed to a widely distributed, slow negative process, which began on the N1‐P2 deflection, peaked at N2, and terminated beyond P3, and was enhanced when an automatically generated expectancy of a semantically associated word was violated. It is suggested that the negativity reflects an automatically generated enhancement of arousal that facilitates conscious processing of unexpected stimuli.
REM/NREM Discrimination via Ocular and Limb Movement Monitoring: Correlation with Polygraphic Data and Development of a REM State Algorithm
Authors: Helfand Rita , Lavie Peretz , Allan Hobson J.
Published: February 2007

The purpose of this study was to develop an inexpensive, simplified home monitoring system for prescreening certain sleep complaints and for long‐term home‐based experiments. Four subjects slept in the laboratory for 3–4 nights. In addition to a standard polysomnogram, piezoelectric ceramic transducers were attached to both hands, both feet, and over the right eyelid.

The sleep from 2 nights of each subject was staged according to the standard criteria. The limb transducers identified major and minor body shifts and were used to signal possible state changes. The data from the eye movement sensor was used to develop a REM‐state algorithm.

Using this algorithm, REM and NREM sleep were identified with 92% (SD=0.091) and 91% (SD=0.076) accuracy, respectively. The ultimate goal is to have a bedside device programmed with the algorithm that would either store information or score the data on‐line for waking, NREM, and REM states.

We conclude that a system monitoring eye movements and major body shifts is a promising approach to an economical and accurate home recording system.
P300 Development from Auditory Stimuli
Authors: Polich John
Published: February 2007

Event‐related potentials (ERPs) were elicited with an auditory discrimination paradigm in 20 adult subjects. The amplitude and latency of the N1, P2, N2, and P3 (P300) components were measured from each two‐trial average and successively after each two‐trial block were added to the ERP average. The dual trial‐to‐trial analysis generally demonstrated consistent component amplitudes and latencies across trials. The successive average analysis found that component amplitudes decreased significantly while their latencies remained relatively constant as additional trials were incorporated into the average. The results suggest that ERP component latencies are stable, while amplitudes decrease with increased numbers of trials. The implications for the application of P3 in the assessment of individual differences are discussed.
Stimulus Omission and Dishabituation of the Electrodermal Orienting Response: The Allocation of Processing Resources
Authors: Siddle David A.T. , Packer Jeanette S.
Published: February 2007

The present research investigated the effects of stimulus omission on electrodermal orienting, dishabituation. and the allocation of processing resources as assessed by reaction time (RT) to a secondary probe stimulus. All experiments employed 33 tone‐light or light‐tone (S1‐S2) pairings, and for experimental groups, S2 was omitted on 4 trials, experiment 1 (N = 24) demonstrated reliable electrodermal responding when S2 was omitted for a trial, and subsequent dishabituation when S2 was then re‐presented after SI on the immediately following trial. Experiment 1 (N=96) employed probe RT as the dependent variable. White noise probe stimuli were presented 300 ms or 1300 ms following the omission of S2 and following its onset on re‐presentation trials. Reaction time to probes presented during S2 omission was slower in experimental groups than in control groups. Reaction time on S2 re‐presentation trials was also slower in experimental groups than in control groups, but only when S3 was a tone. Experiment 3 (N=48) employed auditory and visual probes presented 1300 ms following S2 omission and S2 re‐presentation, and measured both electrodermal activity and probe RT, Some evidence of electrodermal omission responding and dishabituation was obtained. Reaction time was again slowed during the omission and re‐presentation of S2. regardless of the modality of S2 and regardless of the modality of the probe. The results are interpreted as consistent with an information‐processing approach to orienting and habituation in that they indicate that both the omission and re‐presentation of an expected stimulus command processing resources.
Changes in Heart Rate and Slow Brain Potentials Related to Motor Preparation and Stimulus Anticipation in a Time Estimation Task
Authors: Damen E.J.P. , Brunia C.H.M.
Published: February 2007

Based on previous research, it was hypothesized that both the final cardiac deceleration and the late wave of the Contingent Negative Variation (CNV) at the end of the foreperiod of a simple reaction time task are composed of a movement‐related component and a stimulus‐anticipation component. Forty right‐handed adult female and male subjects performed a time estimation task. They had to press a button with the index‐finger at intervals of 20 to 22 seconds. After the button‐press a visual stimulus was presented, which provided Knowledge of Results (KR) about the correctness of the timing. For half the subjects the delay between button‐press and stimulus presentation was 2 s, for the other half it was 4 s. Recordings of both the electrocardiogram (ECG) and the electroencephalogram (EEG) were obtained, the latter being derived bilaterally from precentral. postcentral. and parietal sites. As was expected, cardiac deceleration was found both prior to the movement and prior to stimulus presentation in both delays. At the cortical level the movement was preceded by a Readiness Potential (RP). Stimulus presentation was preceded by a cortical negative wave, the Stimulus‐Preceding Negativity (SPN), at all positions. Precentrally and postcentrally the Stimulus‐Preceding Negativity exhibited a larger right hemisphere preponderance in the 2‐s delay than in the 4‐s delay.
Visual Evoked Potentials to Illusory Reversals of the Necker Cube
Authors: O'Donnell B.F. , Hendler T. , Squires N.K.
Published: February 2007

Sensory adaptation and cognitive evaluation have been proposed as explanations of illusory figure reversals. The effect of variations in the perceived orientation of a Necker cube on visual evoked potentials (VEPs) was studied to test these two hypotheses. VEPs associated with perceptual reversals and non‐reversals of a Necker cube were compared with VEPs elicited by a sequence of physically varying cubical figures. Amplitude differences in the early VEP components consistent with adaptation effects were not detected. Both types of reversals were associated with a late positive component (400–700 ms), which was smaller in amplitude in the illusory condition. The late positivity to illusory reversals was also distinguished by a broad (200–700 ms) positive component over frontal and central recording sites which was absent over Oz. These findings suggest that illusory reversals are more difficult to discriminate than physical reversals, and require additional cognitive resources for evaluation.
Temporal Dynamics of Human Auditory Selective Attention
Authors: Hansen Jonathan C. , Hillyard Steven A.
Published: February 2007

Event‐related potentials (ERPs) were recorded from human subjects in response to short trains of rapidly presented tone pips of two frequencies. Subjects listened selectively to tones of one frequency as directed by a visual cue prior to each train and responded to occasional longer‐duration target tones of that frequency. The early negative difference (Nd) between ERPs elicited by the tones when attended versus unattended was minimal for the first stimulus in each train but developed rapidly, attaining stable values by about the third stimulus. The development of this early Nd was most rapid when two attended tones began a train. Long time‐base averages revealed the concomitant development of a standing negativity over the course of each train. In contrast, late positive ERPs distinguished attended from unattended target tones even when they occurred in the first position of a train, prior to the development of Nd. The latency of this late positivity together with the reaction time to the targets decreased substantially as the Nd developed. It was concluded that subjects can select stimuli at various stages of analysis, but employment of the early selection mechanism indexed by Nd enables an economy of processing and faster and more accurate task performance. This mode of early selection is not pre‐set in advance of a stimulus train, however, at least under the present conditions.
Memory Retrieval in Noise and Psychophysiological Response in the Young and Old
Authors: Jennings J. Richard , Nebes Robert , Brock Kay
Published: February 2007

Both noise and aging induce changes in memory performance that have been attributed to physiological overarousal. The aim of the current experiment was to examine variation in performance due to noise and aging and to determine if this variation was related to variation in general arousal or, alternatively, to changes in processes specifically required by memory retrieval. The cardiovascular responses of young and old men (n=30) were compared during a memory retrieval task performed in acoustic noise. Noise (90dBA) and old age independently increased the number of associatively cued recall errors relative to orthographically cued recall errors. Despite the change in errors, changes in general arousal were not observed in response to noise in either young or old volunteers. The task sequence induced consistent cardiac and vascular responses which were related to attention and rehearsal requirements, and also to performance. This suggests that task processing induces supportive physiological changes rather than that physiological change (arousal) constrains performance. Noise and age may alter physiological change independently by altering task processing and requirements for physiological support.
Electrodermal Lability and Visual Information Processing
Authors: Wilson Keith G. , Graham Randall S.
Published: February 2007

Individual differences in electrodermal lability have been related to performance in vigilance and reaction time tasks. The goal of the present study was to employ an “additive factors’ approach to identify the stages of information processing that might underlie these effects. Nineteen labile and 17 stabile subjects performed a choice reaction time task in which a visual imperative stimulus was presented under two conditions of intensity (presumed to affect the speed of pre‐processing operations) X three conditions of degradation (which influences later encoding processes related to feature extraction). Measures of both reaction time and movement time were obtained. The major findings were: (a) labile subjects had faster reaction times than stabiles, and (b) lability interacted significantly with stimulus degradation. Labiles also tended (p<.10) to have faster movement times. This pattern indicates that labiles and stabiles differ in the performance of later encoding operations, and possibly in the speed of motor processes as well. However, they do not appear to differ in the early pre‐processing of the simple physical attributes of a stimulus.
Sleep on the Night Shift: 24‐Hour EEG Monitoring of Spontaneous Sleep/Wake Behavior
Authors: Torsvall Lars , Akerstedt Torbjöurn , Gillander Katja , Knutsson Anders
Published: February 2007

The present study sought to objectively describe the spontaneous sleep/wakefulness pattern of shift workers during a 24‐hour period. Portable Medilog tape‐recorders were used for ambulatory EEG monitoring of 25 male papermill workders (25–55 years) during days with night and afternoon work. The rusults showed that sleep after night work was two hours shorter than after afternoon worl. The sleep reduction affected mainly Stage 2 and REM sleep while slow wave sleep was unchanged. In connection with night work 28% of the workders took a nap in the afternoon. These naps contained a large proportion of slow wave sleep and were, apparently, caused by the sleep deficit after the short main sleep period. The EEG recordings also revealed that 20% of the participants had sleep episodes during night work. These naps were as long as the afternoon naps, were experienced as “dozing off” ragher than naps. Occurred at the time of the though of the circadian wakefulness rhythm, and were concomitant with extreme subjective sleepiness and low rated work load. It was concluded that not only the sleep of shift workders was disturbed, but also the wakefulness‐ to the extent that sleepiness during night work sometimes reached a level where reasonable wakefulness could not be maintained. The latter observation is probably of special importance in work situations demanding a great responsiility of human lives or for great economic values.
Self‐Report During Feedback Regulation of Slow Cortical Potentials
Authors: Roberts Larry E. , Birbaumer Niels , Rockstroh Brigitte , Lutzenberger Werner , Elbert Thomas
Published: February 2007

Subjects received exteroceptive feedback for bidirectional changes in slow cortical potentials or alpha power measured from the vertex. The slow potential group succeeded in shifting slow potentials toward negativity and positivity on feedback and transfer trials requiring these changes, after two sessions of training. Differentiation of negativity and positivity was accompanied by verbal reports of somatomotor activation that occurred on trials on which negative slow potentials were required (p < .01). Vertical and lateral eye movements, chin and frontalis electromyogram, and heart rate did not differentiate between negativity and positivity trials in the slow potential group. However, heart rate acceleration correlated between‐subjects with slow potential negativity during feedback. Although the alpha power group did not succeed at controlling changes in alpha, evidence of a training effect appeared in verbal reports of emotional arousal (p< .05) and focused vision (p< .08) on alpha suppression trials in this group. We discuss the findings from the viewpoint that biofeedback tasks involving electrocortical responses are problems in the organization of action that subjects seek to solve.
Development and Stability in Visual Sustained Attention in 14, 20, and 26 Week Old Infants
Authors: Richards John E.
Published: February 2007

Infants were studied at 14, 20, and 26 weeks of age in a longitudinal design. They were presented with varying and complex patterns on a TV screen. Two‐thirds of the presentations were accompanied by a stimulus in the periphery delayed in time from the onset of fixation on the central stimulus. As in previous research, the infants were not as easily distracted by the interrupting stimulus when the presentation occurred at the point of maximal heart rate deceleration as when the presentation occurred at the end of the heart rate response. Infants with large amounts of respiratory sinus arrhythmia (i.e., heart rate variability) in a baseline recording were less distractible during the deceleration‐defined trials than were infants with low amounts of respiratory sinus arrhythmia. Intra‐individual patterns of development in respiratory sinus arrhythmia over the testing ages were closely paralleled by patterns of heart rate responding during sustained attention. Individual differences in baseline levels of heart rate and respiratory sinus arrhythmia were more stable than individual differences in sustained attention. The stability of attention responses over age may be mediated by the stability of the physiological system (e.g., heart rate, respiratory sinus arrhythmia, etc.), and by the within‐age relation of attention to heart rate variability.
Modulation of Event‐Related Potentials by Word Repetition: The Effects of Inter‐Item Lag
Authors: Nagy Margaret E. , Rugg Michael D.
Published: February 2007

The modulation of event‐related potentials by word repetition was investigated in two experiments. In both experiments, subjects responded to occasional nonwords interspersed among a series of words. A proportion of the words were repetitions of previously presented items. Words were repeated after 0 or 6 intervening items in Experiment 1 and after 6 or 19 items in Experiment 2.

Event‐related potentials to repeated words were characterised by a sustained, widespread positive‐going shift with an onset of approximately 300 ms. This effect did not vary significantly as a function of lag in either experiment. When words were repeated immediately, this repetition‐evoked positive shift was preceded by a transient negative deflection (onset ca. 200 ms) which was absent in event‐related potentials to words repeated at longer lags.

These results suggest that the modulation of event‐related potentials by word repetition is influenced by at least two processes. One of these processes acts relatively early during the processing of a repeated word, but subsides rapidly as inter‐item lag between first and second presentations increases. The second process occurs later in time, but is considerably more robust over variations in inter‐item lag.
Bootstrapping: Applications to Psychophysiology
Authors: Wasserman Stanley , Bockenholt Ulf
Published: February 2007

This paper presents the statistical technique known as thebootstrapto the general audience of psychophysiologists. The bootstrap, introduced by Efron (1979), allows data analysts to study the distribution of sample statistics that might otherwise be too complicated to consider. The technique, which requires simple calculations, involves drawing repeated samples (with replacement) from the empirical–or the actual–data distribution and then building a distribution for a statistic by calculating a value of the statistic for each sample. The bootstrap can be used to obtain confidence intervals, standard errors, and even higher moments for the statistic. It is similar to the well‐known jackknife of Quenouille and Tukey. After discussing the history and theory of both the bootstrap and the jackknife, we illustrate the use of the bootstrap in the statistical analysis of correlation coefficients and the general linear model.
Cognitive Determinants of the Postimperative Negative Variation
Authors: Kathmann Norbert , Jonitz Lothar , Engel Rolf R.
Published: February 2007

This study examined cognitive determinants of the postimperative negative variation (PINV). a slow brain potential observable after the onset of an imperative stimulus in a forewarned reaction time task. Controllability of the aversive imperative stimulus by a motor reaction and predictability of the contingency were varied in a factorial design. The exogenous portion of the slow negative wave was assessed in a passive listening condition using tones of the same quality as the imperative stimuli. but presented without forewarning. Results show that PINV not only occurs when control is absent but also during unpredictably gained control. Similarly, unpredictable lack of control yields a more negative potential than continual helplessness. Negativity elicited by the aversive tone alone was not significantly different from PINV during predictable lack of control. The order of conditions, which was manipulated between groups, did not affect amplitudes. It was concluded that contingency change is a crucial cognitive determinant of the PINV, whereas the effect of lack of control is difficult to differentiate from the sensory influence of the acoustic stimulation.
Intergroup and Intrasubject Principal Component Analysis of Event‐Related Potentials
Authors: Guthrie Donald
Published: February 2007

The purpose of this paper is to show that the familiar principal component analysis (PCA) of event‐related potentials is identical to an easily formulated least squares method. This correspondence permits interpretation of several criticisms of PCA and clearer presentation of its strengths and shortcomings. Because data analysis based on PCA compares amplitudes of empirically derived components, it is necessary that the shape of the components be similar under the experimental conditions. We present and illustrate a statistical method for comparison of principal components across groups and between conditions within subjects.
The Relationship Between Skin Conductance Orienting the Allocation of Processing Resources
Authors: Filion Diane L. , Dawson Michael E. , Schell Anne M. , Hazlett Erin A.
Published: February 2007

Information processing models of autonomic orienting suggest that the elicitation of an orienting response is associated with either the call for, or the actual allocation of, limited attentional processing resources. However, Dawson, Filion, and Schell (1989) reported a directional dissociation between elicitation of the skin conductance orienting response and resource allocation, as indexed by reaction time slowing on a secondary task. Although larger skin conductance responses were elicited by a task‐relevant stimulus than by a task‐irrelevant stimulus, reaction time showed the opposite pattern (i.e., greater slowing to secondary task probes presented shortly following the onset of the task‐irrelevant stimulus). In the present report, we describe three experiments which examine the generality of this dissociation effect and test specific hypotheses regarding its nature. Results of the first two experiments revealed that the dissociation effect is observed reliably when the taskrelevant and task‐irrelevant stimuli consist of left ear and right ear tones or high and low pitched binaural tones, across a range of secondary task probe presentation times. However, the third experiment demonstrated that when task‐relevant and task‐irrelevant stimuli are presented to different sensory modalities (auditory and visual), orienting and resource allocation are both greater during the task‐relevant than the task‐irrelevant stimuli, thus eliminating the dissociation effect. These results support the hypothesis that the dissociation effect is due to a switch of attention initiated because of the physical similarity of the task‐relevant and task‐irrelevant stimuli, and suggest that there is a fundamentally positive relationship between skin conductance orienting and resource allocation under selective attention conditions.
Probing the Time‐Course of the Auditory Oddball P3 With Secondary Reaction Time
Authors: Woodward Steven H. , Brown Warren S. , Marsh James T. , Dawson Michael E.
Published: February 2007

An elementary neural model of the P3 is proposed in which the P3 is held to manifest a brief, widely‐distributed, inhibitory event. A preliminary and indirect test of the model is described using secondary‐task methodology. Manual reaction times were measured to probe clicks delivered during the presumed time‐course of an auditory oddball P3. We observed that reaction times to probes presented after oddball stimuli were significantly slowed as compared to reaction times to probes presented after standards. The latency of maximum reaction time slowing corresponded generally to the latency of the P3. The latency of maximum reaction time slowing did not respond to a manipulation varying the latency of the P3. Thus, some of the obtained results were consistent with the P3‐inhibition hypothesis, whereas others were not. Secondary‐task methodology may provide a valuable new approach to understanding the late event‐related potentials.
Abnormal Processing of Affective Words by Psychopaths
Authors: Williamson Sherrie , Harpur Timothy J. , Hare Robert D.
Published: February 2007

We tested the hypothesis that psychopathy is associated with abnormal processing of affective verbal material. Criminal psychopaths and nonpsychopaths, defined by the Psychopathy Checklist, performed a lexical decision task (“Is it a word or not”) while we recorded reaction time and eventrelated potentials in response to letter‐strings consisting of affective and neutral words and pronounceable nonwords. On the assumption that they do not make efficient use of affective information, our primary prediction was that psychopaths would show less behavioral and eventrelated potential differentiation between affective and neutral words than would nonpsychopaths. The results were in accordance with this prediction. The lexical decisions of nonpsychopaths were significantly faster, and relevant event‐related potential components were significantly larger, to affective words than to neutral words. In sharp contrast, psychopaths failed to show reaction lime facilitation or larger amplitude event‐related potentials to affective words. We suggest that psychopaths extract less information from affective words than do other individuals. Possible implications of these and related findings for understanding the behavior of psychopaths are discussed.
A Nonstationarity Test for the Spectral Analysis of Physiological Time Series with an Application to Respiratory Sinus Arrhythmia
Authors: Weber Edith J.M. , Molenaar Peter C.M. , van der Molen Maurits W.
Published: February 2007

The spectral analysis of time series requires the signal to be at least weakly statonary; i.e., the mean, (co‐) variance, and spectrum of the time series should not vary from segment to segment. It is commonly assumed that psychophysiological time series are not stationary. This study introduces a nonstationarity test to the psychophysiological literature, which is derived from evolutionary spectral analysis. Basically, the test consists of a double window technique in both the time and frequency domains, leading to a two‐way analysis of variance for times and frequencies. In the current study, the nonstationarity test is applied to heart rate data obtained in a typical psychophysiological setting. Heart rate and respiration were measured in four age groups under four conditions—rest, paced breathing, vigilance, and reaction time. The results indicate that only few physiological time series were completely stationary. However, for every subject, and in every condition stationary strectches could be found that were long enough to apply spectral analysis. Spectral measures (power, coherence, and phase spectra) were then compared for stationary parts of the data and the total data. This comparison indicated that nonstationarity affects all spectral measures. Most importantly, Stationarity × Task Condition × Frequency Band interactions were observed for coherence and phase spectra, and there were significant interactions with age for each of the spectral indices. These findings suggest that nonstationarity may result in biased outcomes of significance tests of the effects of task manipulations on the spectral indices of cardiac time series. Thus, it was concluded that the stationarity test should be routinely applied in the spectral analysis of physiological time series. In addition, it was suggested that the nonstationarity test has an even wider range of application that might be of interest to the psychophysiologist.
Pictures as prepulse: Attention and emotion in startle modification
Authors: BRADLEY MARGARET M. , CUTHBERT BRUCE N. , LANG PETER J.
Published: February 2007

The effects of an emotional stimulus prepulse on probe startle response were examined here. Pleasant, neutral, and unpleasant pictures were viewed for 6 s, and an acoustic startle probe was presented either 300, 800, 1,300, or 3,800 ms after slide onset, or 300 or 3,800 ms after slide offset. Blink magnitude and onset latency demonstrated (a) an early (prepulse) inhibition effect in which reflexes elicited immediately after slide onset were smaller than reflexes elicited later in the viewing interval, and (b) affective modulation, in which unpleasant stimuli prompted larger reflexes than pleasant. Interactive effects of probe time and picture valence indicated attention/arousal effects early and pleasantness effects late in the picture interval. Effects of both attention and emotion can be simultaneously measured using this startle‐probe paradigm, encouraging its use in both basic and clinical contexts.
Cardiovascular activity during mental stress following vigorous exercise in sportsmen and inactive men
Authors: STEPTOE ANDREW , KEARSLEY NICOLA , WALTERS NICK
Published: February 2007

Thirty‐six competitive sportsmen and 36 inactive men participated in a two‐session experiment. Session 1 involved exercise to exhaustion so as to assess maximal oxygen consumption (V̇o2 max. In Session 2, both groups were randomized into three experimental conditions: 20 min of exercise at high intensity (70%V̇o2 max) or moderate intensity (50% V˙o2 max) or a light exercise control. Following 30 min of recovery, all subjects performed mental arithmetic and public speech tasks in a counterbalanced order. Cardiovascular, electrodermal, respiratory, and subjective variables were recorded. Sportsmen had higher V˙o2 max, lower body fat, and lower resting heart rate (HR) than inactive men. A postexercise hypotensive response was observed among subjects in the 70% and 50% V˙o2 max conditions, accompanied by baroreceptor reflex inhibition in the 70% condition. Systolic pressure was lower during mental arithmetic and during recovery from the speech task in the high‐intensity than in the control group. Diastolic pressure was lower following mental arithmetic in the high‐intensity group. No differences in HR reactivity, electrodermal, or respiratory parameters were observed, but baroreceptor reflex sensitivity was inhibited during mental arithmetic. The results are discussed in relation to previous reports of suppressed cardiovascular reactivity to mental stress tests following vigorous exercise and the role of stress‐related processes in the antihypertensive response to physical training.