Stimulus–response bindings in priming
Authors: Richard N. Henson, Doris Eckstein, Florian Waszak, Christian Frings, Aidan J. Horner
Journal: Trends in Cognitive Sciences (2014)

•S–R bindings are more flexible and pervasive than previously thought.•S–R bindings can simultaneously encode multiple stimulus and response representations.•S–R bindings can be encoded or retrieved in the absence of attention or awareness.•S–R bindings complicate interpretations of priming, but are interesting in their own right.•S–R bindings enable rapid yet context-dependent behaviors. People can rapidly form arbitrary associations between stimuli and the responses they make in the presence of those stimuli. Such stimulus–response (S–R) bindings, when retrieved, affect the way that people respond to the same, or related, stimuli. Only recently, however, has the flexibility and ubiquity of these S–R bindings been appreciated, particularly in the context of priming paradigms. This is important for the many cognitive theories that appeal to evidence from priming. It is also important for the control of action generally. An S–R binding is more than a gradually learned association between a specific stimulus and a specific response; instead, it captures the full, context-dependent behavioral potential of a stimulus. People can rapidly form arbitrary associations between stimuli and the responses they make in the presence of those stimuli. Such stimulus–response (S–R) bindings, when retrieved, affect the way that people respond to the same, or related, stimuli. Only recently, however, has the flexibility and ubiquity of these S–R bindings been appreciated, particularly in the context of priming paradigms. This is important for the many cognitive theories that appeal to evidence from priming. It is also important for the control of action generally. An S–R binding is more than a gradually learned association between a specific stimulus and a specific response; instead, it captures the full, context-dependent behavioral potential of a stimulus. IntroductionOur daily lives involve interacting with a large number of stimuli. Many of these stimuli occur not only once, but recur at different timescales. We therefore need to learn rapidly how to process these recurring stimuli, without necessarily intentionally recalling prior experiences with those stimuli. One example of this rapid learning is priming, in which a change in the mental processing of a stimulus is normally measured by an overt behavioral response cued by that stimulus (Box 1). Priming is often interpreted as facilitation of one or more of the computations, or 'component processes' [1Roediger III, H.L. et al.Explaining dissociations between implicit and explicit measures of retention: a processing account.in: Roediger III, H.L. Craik F.I.M. Varieties of Memory and Consciousness: Essays in Honor of Endel Tulving. Erlbaum, 1989: 67-84Google Scholar], that are necessary to generate that response. In a typical laboratory experiment, for example, participants might press one of two buttons depending on whether they judge a visually presented object to be living or nonliving, for which priming would be apparent if their average reaction time (RT) for this judgment is shorter for repeated than for initial presentations of the objects. In this example, the component processes that are facilitated might include perceptual identification of the object depicted (perceptual priming) and/or retrieval of semantic information about that object (conceptual priming).Box 1Major types of primingPriming refers to a change in accuracy, bias, or reaction time to respond to a stimulus ('probe') owing to prior presentation of the same or a similar stimulus ('prime'). It is indexed as the difference between the response to the prime and probe or between the probe and a comparable stimulus not presented before ('unprimed'). There are at least three main priming paradigms, which differ in whether a response is made to: (i) the prime; and/or (ii) the probe (see Figure 1B in main text).In repetition priming, a response is made to both prime and probe. The prime and probe typically occur in separate trials separated by multiple intervening trials (so that priming does not simply owe to repetition of the same response across successive trials; that is, 'response priming'). Note that the stimulus may not be repeated in exactly the same physical form (e.g., it may switch from a written to a spoken word across trials).In negative priming, the prime (and sometimes the probe) is a distractor; that is, it is not the focus of attention, such that the response is generated instead by a different, concurrent stimulus. Responses are typically slowed when the prime is then presented as a probe in a subsequent trial (although note that priming is not always 'negative' in the sense of a slowing; positive priming can occur if the response previously paired with the prime is congruent with that required to the probe).In masked priming, the prime is masked to render it subliminal, such that no response can be made to it. The subsequent supraliminal probe typically occurs within a few hundred milliseconds (i.e., within the same trial). The S–R binding that is potentially retrieved by the masked prime then usually comes from previous presentations of the same stimulus as a probe in other trials.These paradigms differ in other ways too. For example, repetition priming can survive lags of many intervening trials and sometimes last days, whereas negative priming typically occurs only across successive trials and masked priming rarely lasts beyond one trial. There are also other priming paradigms (e.g., semantic/affective priming, where prime and probe are different stimuli but semantically or affectively related), but here we focus on paradigms in which S–R bindings have been shown to play a dominant role, and these normally involve repeating a stimulus to cue retrieval of an S–R binding (although see text about possible F–R bindings).However, it has long been suspected that priming can also result from directly associating, or binding, a stimulus and response. If these S–R bindings are retrieved when the stimulus is repeated, the response can be produced without necessarily recapitulating the component processes that were initially used to generate that response (Figure 1A) . Evidence for S–R bindings has been found in all major priming paradigms (Box 1 and Figure 1B): repetition priming [2Logan G.D. Repetition priming and automaticity: common underlying mechanisms?.Cogn. Psychol. 1990; 22: 1-35Crossref Scopus (403) Google Scholar], negative priming [3Rothermund K. et al.Retrieval of incidental stimulus–response associations as a source of negative priming.J. Exp. Psychol. Learn. 2005; 31: 482-495Crossref PubMed Scopus (195) Google Scholar], and masked priming [4Damian M.F. Congruity effects evoked by subliminally presented primes: automaticity rather than semantic processing.J. Exp. Psychol. Hum. Percept. Perform. 2001; 27: 154-165Crossref PubMed Scopus (199) Google Scholar].The study of S–R bindings is important for two reasons. First, the presence of S–R bindings potentially confounds interpretation of many priming effects; for example, whether unattended items are truly inhibited [5Tipper S.P. Does negative priming reflect inhibitory mechanisms? A review and integration of conflicting views.Q. J. Exp. Psychol. (Colchester). 2001; 54A: 321-343Crossref Scopus (524) Google Scholar, 6Wühr P. Frings C. A case for inhibition: visual attention suppresses the processing of irrelevant objects.J. Exp. Psychol. Gen. 2008; 137: 116-130Crossref PubMed Scopus (50) Google Scholar] or whether semantic representations can really be accessed unconsciously [4Damian M.F. Congruity effects evoked by subliminally presented primes: automaticity rather than semantic processing.J. Exp. Psychol. Hum. Percept. Perform. 2001; 27: 154-165Crossref PubMed Scopus (199) Google Scholar, 7Marcel A.L. Conscious and unconscious perception: experiments on visual masking and word recognition.Cognit. Psychol. 1983; 15: 197-237Crossref PubMed Scopus (897) Google Scholar]. More importantly, S–R bindings are now recognized to play a vital role in the control of action; a role that goes beyond the mere acceleration of stimulus-driven action. For example, research reviewed below indicates that S–R bindings encode information at multiple levels of abstraction, furnishing considerable flexibility and context sensitivity in their deployment. However, despite the recent interest in S–R bindings, many crucial questions remain unanswered.Ubiquity and flexibility of S–R bindingsAlthough the concept of S–R bindings is not new (Box 2), a recent resurgence in interest has been driven by evidence for their greater prevalence and flexibility than previously thought. For example, S–R bindings are far from being simple associations between a specific stimulus and specific response; rather, they appear to be structured bindings involving multiple levels of representation of responses, stimuli, and tasks (Figure 2). Moreover, these bindings do not need to be gradually learned; they can be formed from a single pairing of a stimulus and response.Box 2S–R theoriesThere are many theories relating to S–R bindings; we focus on one example pertinent to each of the three priming paradigms considered here (Box 1).Logan proposed an 'instance theory' [64Logan G.D. Toward an instance theory of automatization.Psychol. Rev. 1988; 95: 492-527Crossref Scopus (2313) Google Scholar] of automaticity that has been mainly applied to repetition priming. Responses are determined by a race between an algorithmic route (comprising computations used to produce a response the first time a stimulus is encountered) and retrieval of any relevant S–R bindings (with a separate such 'instance' stored each time a response is given to a stimulus). Assuming that all S–R bindings race independently, RTs will decrease with the number of instances according to a power law, with the mean and standard deviation having the same exponent. A later version of the theory [74Logan G.D. An instance theory of attention and memory.Psychol. Rev. 2002; 109: 376-400Crossref PubMed Scopus (307) Google Scholar] included two additional decision rules (a counter and a random-walk model) that prioritize response accuracy at the cost of increased RTs in conflict situations. With this extension, instance theory can also potentially explain negative priming.Hommel [31Hommel B. Event files: evidence for automatic integration of stimulus–response episodes.Vis. Cogn. 1998; 5: 183-216Crossref Scopus (621) Google Scholar] hypothesized the existence of 'episodic records'. These encode features of stimuli and responses, with each record binding only two features (which can be from different stimuli), although the same feature can occur in multiple records. Hommel's theory was developed primarily to explain 'carry-over' costs from one trial to the next (such as negative priming), rather than longer-lived facilitatory effects seen in repetition priming paradigms.Kunde et al. [75Kunde W. et al.Conscious control over the content of unconscious cognition.Cognition. 2003; 88: 223-242Crossref PubMed Scopus (254) Google Scholar] proposed an 'action trigger' theory (see also [76Neumann O. Direct parameter specification and the concept of perception.Psychol. Res. 1990; 52: 207-215Crossref PubMed Scopus (174) Google Scholar]), which is most often applied to masked priming. The basic idea is that repeated pairings of a stimulus and response establish a trigger that releases an action when a related stimulus reappears. The generalization to related stimuli comes from being able to specify the trigger conditions in broad terms. For example, evidence that the masked digit '3' can prime a relative size judgment to a subsequent probe '4', even if the 3 was not presented previously in the experiment [60Naccache L. Dehaene S. Unconscious semantic priming extends to novel unseen stimuli.Cognition. 2001; 80: 223-237Crossref Scopus (282) Google Scholar], can be explained by a generic trigger of the sort 'small numbers should produce a "no" response'.Although these S–R theories have proved helpful, each needs further development to explain the precise role of attention and awareness during encoding and retrieval of S–R bindings (see text) and their interactions with other component processes. Moreover, few if any theories specify neural mechanisms that can be compared with recent brain data (Box 3).Figure 2Possible stimulus–response (S–R) binding. Schematic of a possible structured S–R binding formed by giving a response to a picture of a lion during a binary 'bigger than shoebox?' categorization task, where red lines indicate bindings. Stimulus representations include a visual image of the picture and a more abstract representation of the identity of that stimulus, such that if the word 'lion' is later presented, it can also cue responses via the bindings between the identity representation and response representations. Response representations include a specific motor action (e.g., right index finger depression), a binary decision (e.g., 'yes') and a particular classification (e.g., 'bigger' in the size task). This means that retrieval of an action or decision can influence responses even if the task is changed; for example, to an 'is the object living?' categorization instead (as shown). Similarly, retrieval of a decision can influence responses even if the effector (action) is changed and retrieval of a classification can influence responses even if the task (and hence decision and action) is reversed (e.g., to a 'smaller than shoebox?' task). Retrieval of the S–R binding may also be mediated by the spatial/temporal context (e.g., laboratory setting).View Large Image Figure ViewerDownload (PPT)The nature of 'R'Despite evidence for effector-specific response codes [8Eimer M. et al.Locus of inhibition in the masked priming of response alternatives.J. Mot. Behav. 2002; 34: 3-10Crossref PubMed Scopus (56) Google Scholar], there is general agreement that responses can also be represented by their goal, rather than just specific motor programs [9Eder A.B. et al.The structure of affective action representations: temporal binding of affective response codes.Psychol. Res. 2012; 76: 111-118Crossref PubMed Scopus (32) Google Scholar, 10Prinz W. Perception and action planning.Eur. J. Cogn. Psychol. 1997; 9: 129-154Crossref Scopus (1442) Google Scholar]. Priming effects that survive a switch in effector between prime and probe are consistent with this claim (e.g., [11Mayr S. et al.Evidence of vocal and manual event files in auditory negative priming.Exp. Psychol. 2011; 58: 353-360Crossref PubMed Scopus (13) Google Scholar] in the case of negative priming).However, priming that is invariant to a change in effector is not necessarily evidence for abstract response representations in S–R bindings, because the residual priming could reflect other factors, like facilitation of component processes (or inhibition of a stimulus representation in the case of [11Mayr S. et al.Evidence of vocal and manual event files in auditory negative priming.Exp. Psychol. 2011; 58: 353-360Crossref PubMed Scopus (13) Google Scholar]). To identify the level of response representation within an S–R binding, one must measure the difference in priming between a congruent condition (where the same response is given each time a stimulus is presented) and an incongruent condition (where the opposite response is given) or an unrelated condition (where a different type of response is given). In the case of repetition priming, for example, Horner and Henson [12Horner A.J. Henson R.N. Bindings between stimuli and multiple response codes dominate long-lag repetition priming in speeded classification tasks.J. Exp. Psychol. Learn. 2009; 35: 757-779Crossref PubMed Scopus (102) Google Scholar] showed a reduction in priming when the response to a repeated stimulus switched from a vocal yes/no to a manual key press (relative to the congruent condition of a manual response to both prime and probe). This suggests that the specific motor action is indeed encoded in the S–R binding. However, priming from a vocal yes/no response to manual response was still greater than when the prime object was simply named. This suggests that S–R bindings additionally encode more abstract response representations, such as a yes/no decision (see also [13Dennis I. Perfect T.J. Do stimulus–action associations contribute to repetition priming?.J. Exp. Psychol. Learn. 2013; 39: 85-95Crossref PubMed Scopus (17) Google Scholar]).Further research has suggested that S–R bindings can encode even more abstract response representations, such as the particular classification made (such as living versus nonliving) [14Koch I. Allport A. Cue-based preparation and stimulus-based priming of tasks in task switching.Mem. Cognit. 2006; 34: 433-444Crossref PubMed Scopus (184) Google Scholar, 15Race E.A. et al.Neural priming in human frontal cortex: multiple forms of learning reduce demands on the prefrontal executive system.J. Cogn. Neurosci. 2009; 21: 1766-1781Crossref PubMed Scopus (93) Google Scholar, 16Race E.A. et al.Multiple forms of learning yield temporally distinct electrophysiological repetition effects.Cereb. Cortex. 2010; 20: 1726-1738Crossref PubMed Scopus (40) Google Scholar, 17Waszak F. Hommel B. The costs and benefits of cross-task priming.Mem. Cognit. 2007; 35: 1175-1186Crossref PubMed Scopus (47) Google Scholar, 18Wylie G. Allport A. Task switching and the measurement of "switch costs".Psychol. Res. 2000; 63: 212-233Crossref PubMed Scopus (471) Google Scholar]. By changing the reference object during a relative-size judgment task (an experimental manipulation introduced by [19Denkinger B. Koutstaal W. Perceive–decide–act, perceive–decide–act: how abstract is repetition-related decision learning?.J. Exp. Psychol. Learn. 2009; 35: 742-756Crossref PubMed Scopus (56) Google Scholar]), Horner and Henson [12Horner A.J. Henson R.N. Bindings between stimuli and multiple response codes dominate long-lag repetition priming in speeded classification tasks.J. Exp. Psychol. Learn. 2009; 35: 757-779Crossref PubMed Scopus (102) Google Scholar] found greater repetition priming for objects that maintained the same bigger/smaller classification despite this reference change than for objects for which the classification changed. In the latter case, note that the yes/no decision and motor action were unchanged; only the classification label changed. These data suggest that S–R bindings can simultaneously encode at least three levels of response representation: action, decision, and classification (Figure 2). Furthermore, response representations like these have been shown to have independent [20Moutsopoulou K. Waszak F. Across-task priming revisited: response and task conflicts disentangled using ex-Gaussian distribution analysis.J. Exp. Psychol. Hum. Percept. Perform. 2012; 38: 367-374Crossref PubMed Scopus (30) Google Scholar, 21Moutsopoulou K. Waszak F. Durability of classification and action learning: differences revealed using ex-Gaussian distribution analysis.Exp. Brain Res. 2013; 226: 373-382Crossref PubMed Scopus (12) Google Scholar] effects on behavior.It has also been suggested that stimuli can be bound to nonspecific 'stop codes' that, when retrieved, inhibit responses in any ongoing task [22Verbruggen F. Logan G.D. Long-term aftereffects of response inhibition: memory retrieval, task goals, and cognitive control.J. Exp. Psychol. Hum. Percept. Perform. 2008; 34: 1229-1235Crossref PubMed Scopus (57) Google Scholar, 23Giesen C. Rothermund K. You better stop! Binding "stop" tags to irrelevant stimulus features.Q. J. Exp. Psychol. 2013; 67: 1-24Google Scholar]. It has even been proposed that stimuli can be bound to attentional filters that have been previously applied to those stimuli [24Crump M.J.C. et al.Context-specific learning and control: the roles of awareness, task relevance, and relative salience.Conscious. Cogn. 2008; 17: 22-36Crossref PubMed Scopus (97) Google Scholar]. This has been used to explain stimulus-specific congruency-proportion effects in Stroop tasks, where congruency effects are larger for stimuli that have been presented in contexts with a higher proportion of other congruent stimuli.Multiple simultaneous levels of response representation potentially allow rapid execution of a specific action, as appropriate, for example, if the context (e.g., task) is unchanged, as well as allowing more flexible response options if the context changes. The downside of this flexibility for priming experiments is that simply changing the effector between prime and probe is not sufficient to 'control for' S–R bindings. Likewise, the presence of more specific response codes means that changing tasks between prime and probe is not a sufficient control either, if both tasks require a yes/no decision or the same motor action [25Vriezen E.R. et al.Priming effects in semantic classification tasks.J. Exp. Psychol. Learn. 1995; 21: 933-946Crossref Scopus (74) Google Scholar]. To properly investigate priming irrespective of the influence of S–R bindings, all levels of response representation must be controlled simultaneously [26Horner A.J. Henson R.N. Stimulus–response bindings code both abstract and specific representations of stimuli: evidence from a classification priming design that reverses multiple levels of response representation.Mem. Cognit. 2011; 39: 1457-1471Crossref PubMed Scopus (64) Google Scholar].The nature of 'S'Similar questions relate to the nature of stimulus representations within S–R bindings. Priming, and its modulation by response congruency, has been shown to decrease with decreasing perceptual similarity between prime and probe [19Denkinger B. Koutstaal W. Perceive–decide–act, perceive–decide–act: how abstract is repetition-related decision learning?.J. Exp. Psychol. Learn. 2009; 35: 742-756Crossref PubMed Scopus (56) Google Scholar, 26Horner A.J. Henson R.N. Stimulus–response bindings code both abstract and specific representations of stimuli: evidence from a classification priming design that reverses multiple levels of response representation.Mem. Cognit. 2011; 39: 1457-1471Crossref PubMed Scopus (64) Google Scholar, 27Schnyer D.M. et al.Item to decision mapping in rapid response learning.Mem. Cognit. 2007; 35: 1472-1482Crossref PubMed Scopus (39) Google Scholar], consistent with S–R bindings encoding relatively form-specific representations. However, response congruency effects have also been found despite switching from object pictures to written object names [26Horner A.J. Henson R.N. Stimulus–response bindings code both abstract and specific representations of stimuli: evidence from a classification priming design that reverses multiple levels of response representation.Mem. Cognit. 2011; 39: 1457-1471Crossref PubMed Scopus (64) Google Scholar] or from object pictures to object sounds [28Frings C. et al.Retrieval of event files can be conceptually mediated.Atten. Percept. Psychophys. 2013; 75: 700-709Crossref PubMed Scopus (38) Google Scholar]. This again suggests that S–R bindings can encode multiple levels of stimulus representation, including at the abstract level of stimulus 'identity' (Figure 2).Response congruency effects have been shown for semantically related stimuli [29Perry J.R. Lupker S.J. An investigation of the time course of category congruence and priming distance effects in number classification tasks.Can. J. Exp. Psychol. 2012; 66: 193-203Crossref PubMed Scopus (2) Google Scholar, 30Waszak F. et al.Semantic generalization of stimulus–task bindings.Psychon. Bull. Rev. 2004; 11: 1027-1033Crossref PubMed Scopus (74) Google Scholar]. This raises the question of whether bindings can be formed between responses and the features that comprise stimuli (see [31Hommel B. Event files: evidence for automatic integration of stimulus–response episodes.Vis. Cogn. 1998; 5: 183-216Crossref Scopus (621) Google Scholar]). In the case of masked priming, for example, such 'feature–response' (F–R) bindings may explain priming from stimuli that occur only once in an experiment: so-called 'novel' primes [32Quinn W.M. Kinoshita S. Congruence effect in semantic categorization with masked primes with narrow and broad categories.J. Mem. Lang. 2007; 58: 286-306Crossref Scopus (34) Google Scholar]. This finding has been assumed to exclude S–R bindings (although see Box 2). If related stimuli have been seen (as probes) and paired with a response, such that features of those stimuli become bound with that response, later repetition of some of those features in a novel (but related) prime stimulus may be sufficient to retrieve the response and hence prime the subsequent probe. This hypothesis is consistent with priming by novel words that comprise parts of words seen previously as probes [33Abrams R.L. Greenwald A.G. Parts outweigh the whole (word) in unconsious analysis of meaning.Psychol. Sci. 2000; 11: 118-124Crossref PubMed Scopus (183) Google Scholar] and with claims that masked priming from novel stimuli occurs only when stimuli come from a small and tightly related stimulus set [32Quinn W.M. Kinoshita S. Congruence effect in semantic categorization with masked primes with narrow and broad categories.J. Mem. Lang. 2007; 58: 286-306Crossref Scopus (34) Google Scholar, 34Abrams R.L. Influence of category size and target set size on unconscious priming by novel words.Exp. Psychol. 2008; 55: 189-194Crossref PubMed Scopus (10) Google Scholar, 35Pohl C. et al.Early and late selection in unconscious information processing.J. Exp. Psychol. Hum. Percept. Perform. 2010; 36: 268-285Crossref PubMed Scopus (34) Google Scholar].S–R bindings may also include representations of more than one concurrent stimulus. In negative priming paradigms, for example, there is evidence that the target and distractor stimulus also become bound together, independent of their binding to the response [23Giesen C. Rothermund K. You better stop! Binding "stop" tags to irrelevant stimulus features.Q. J. Exp. Psychol. 2013; 67: 1-24Google Scholar]. Such 'S–S bindings' seem to be determined by the principles of perceptual grouping [36Frings C. Rothermund K. To be or not to be. included in an event file: integration and retrieval of distractors in stimulus–response episodes is influenced by perceptual grouping.J. Exp. Psychol. Learn. 2011; 37: 1209-1227Crossref PubMed Scopus (81) Google Scholar]. There is also evidence of S–S bindings in associative priming tasks where the response requires comparing two or more concurrent stimuli [37Dew I.T.Z. Giovanello K.S. The status of rapid response learning in aging.Psychol. Aging. 2010; 25: 898-910Crossref PubMed Scopus (15) Google Scholar]. Again, these data imply a more complex picture of S–R bindings than is normally conceived, including multiple levels of stimulus as well as response representation, bindings between stimulus features and responses, and bindings between multiple stimuli. This complexity affords yet further flexibility in, for example, allowing learned responses to be triggered not only by the same stimulus, but also by similar stimuli.Contextual bindingsAspects of the concurrent context might also be bound with the stimulus and response. One example is the task set in which a stimulus is encountered. It has been shown that the typical 'task-switch cost', which reflects slower RTs for trials preceded by a different relative to same task, is increased if stimuli are repeated across the tasks [38Waszak F. et al.Task switching and long-term priming: role of episodic stimulus–task bindings in task-shift costs.Cogn. Psychol. 2003; 46: 361-433Crossref PubMed Scopus (478) Google Scholar]. This suggests that the repetition of a stimulus automatically retrieves the previous task set associated with that stimulus, which can interfere with any new task set (also see [14Koch I. Allport A. Cue-based preparation and stimulus-based priming of tasks in task switching.Mem. Cognit. 2006; 34: 433-444Crossref PubMed Scopus (184) Google Scholar, 39Kiesel A. et al.Unconscious priming according to multiple S–R rules.Cognition. 2007; 104: 89-105Crossref PubMed Scopus (31) Google Scholar]). Importantly, Waszak and colleagues [17Waszak F. Hommel B. The costs and benefits of cross-task priming.Mem. Cognit. 2007; 35: 1175-1186Crossref PubMed Scopus (47) Google Scholar, 40Waszak F. et al.Top-down versus bottom-up: when instructions overcome automatic retrieval.Psychol. Res. 2013; 77: 611-617Crossref PubMed Scopus (18) Google Scholar] argued that S–R bindings are more likely to be retrieved if they were compiled under a task set that remains active during the probe trial (given that a previous task set remains active for a certain time after a task switch: so-called 'task-set inertia' [41Allport A. et al.Shifting intentional set – exploring the dynamic control of tasks.in: Umilta C. Moscovitch M. Attention and Performance XV – Conscious and Nonconscious Information Processing. MIT Press, 1994: 421-452Google Scholar]). Task set-dependent retrieval clearly makes adaptive sense, in that one would not want all previous responses that have been associated with a stimulus constantly to compete with current behavioral goals (cf. 'utilization' behavior [42Lhermitte F. Utilization behavior and its relation to lesions of the frontal lobes.Brain. 1983; 106: 237-255Crossref PubMed Scopus (586) Google Scholar, 43Norman D.A. Shallice T. Attention to action: willed and automatic control of behaviour.in: Davidson R.J. Consciousness and Self-regulation. Plenum, 1986: 1-18Crossref Google Scholar]). Other types of spatial or temporal context (e.g., laboratory setting) may also mediate S–R retrieval. Overlap in this level of context may explain why prior responses can still be cued by a repeated stimulus despite a switch in task [12Horner A.J