ArticlePDF Available
Downloaded By: [Swets Content Distribution] At: 10:58 12 March 2007
Editorial: Human contingency learning
Tom Beckers
University of Leuven, Leuven, Belgium
Jan De Houwer
Ghent University, Ghent, Belgium
Helena Matute
Deusto University, Bilbao, Spain
The present special issue presents an overview of
recent developments and controversies in research
on human contingency learning. The aim of this
research is to understand the way in which
humans learn about causal and noncausal relations
between events. It seems quite appropriate that an
issue on human contingency learning is the first
special issue to feature in the newly remerged
Quarterly Journal of Experimental Psychology.In
few areas of research has the interplay between
human and animal experimental research been so
intense and fruitful, with findings and theories
mutually influencing each other. Whereas initially,
research on human contingency learning was
greatly stimulated by the suggestion that models
derived from animal conditioning research cou ld
be applied to human contingency learning (e.g.,
Dickinson, Shanks, & Evenden, 1984; Shanks,
1985), in subsequent decades findings and theor-
etical developments in human learning research
have also begun to stimulate developments in
animal conditioning (e.g., Beckers, Miller , De
Houwer, & Uru shihara, 2006; Miller & Matute,
1996). As such, research on human contingency
learning spans both former sections of the
Quarterly Journal of Experimental Psychology.
Indeed, many papers on contingency learning
that have over the years appeared in either
section could just as well have been published in
the other section. The reunited journal will
undoubtedly represent an enduring forum for the
exchange of ideas and cross-fertilization between
animal and human learning research.
We are very pleased that David Shanks has
kindly agreed to provide an introductory address
for the special issue (Shanks, 2007). It was his
seminal work with Anthony Dickinson (e.g.,
Dickinson et al., 1984; Shanks, 1985, 1986,
1987) that has provided much of the impetus for
the renewed interest in human contingency learn-
ing since the 1980s, and his sustained and import-
ant input to the field has been part of what has
kept the field thriving ever since. His address not
only identifies a number of questions that should
inspire future research, but also provides a
(sometimes provocative) framework for the
contributions that make up this issue. These
contributions range f rom purely fundamental,
theoretical analyses (see the paper by Pinen
Miller, 2007), over empirically oriented reports
(see Booth & Buehner, 2007; Cobos, Lo
pez, &
Luque, 2007; De Houwer, Vandorpe, & Beckers,
2007; Hagmayer & Waldmann, 2007; Karazinov
& Boakes, 2007; Mitchell, Livesey, & Lovibond,
Correspondence should be addressed to Tom Beckers, Department of Psychology, University of Leuven, Tiensestraat 102, 3000
Leuven, Belgium. E-mail:
Tom Beckers is a postdoctoral fellow of the Research FoundationFlanders (FWOVlaanderen, Belgium).
# 2007 The Experimental Psychology Society 289 DOI:10.1080/17470210601000532
2007, 60 (3), 289290
Downloaded By: [Swets Content Distribution] At: 10:58 12 March 2007
2007; Vadillo & Matute, 2007; and Vandorpe, De
Houwer, & Becke rs, 2007), to more applied con-
tributions (see Allan, Siegel, & Hannah, 2007,
and Msetfi, Murphy, & Simpson, 2007), again
reflecting the breadth of contemporary research
on human contingency learning. In compound,
these papers attest to the richness and diversity
of current research on human contingency learning
and indicate key issues that will need to be
addressed in future research.
This special issue originated from an expert
meeting on human contingency learning that the
three of us organized in May 2004 in Lignely,
Belgium. We gratefully acknowledge the support
of the Research FoundationFlanders (FWO
Vlaanderen, Belgium) and the FWO Scientific
Research Network on the Acquisition,
Representation, and A ctivation of Evaluative
Judgements and Emotion in the organization of
this meeting and the compilation of the present
special issue.
Allan, L. G., Siegel, S., & Hannah, S. (2007). The sad
truth about depressive realism. Quarterly Journal of
Experimental Psychology, 60, 482495.
Beckers, T., Miller, R. R., De Houwer, J., &
Urushihara, K. (in press). Reasoning rats: Forward
blocking in Pavlovian animal conditioning is sensi-
tive to constraints of causal inference. Journal of
Experimental Psychology: General.
Booth, S. L., & Buehner, M. J. (2007). Asymmetries in
cue competition in forward and backward blocking
designs: Further evidence for causal model theory.
Quarterly Journal of Experimental Psychology, 60,
Cobos, P. L., Lo
pez, F. J., & Luque, D. (2007). Interference
between cues of the same outcome depends on the
causal interpretation of the events. Quarterly Journal of
Experimental Psychology, 60, 369386.
De Houwer, J., Vandorpe, S., & Beckers, T. (2007).
Statistical contingency has a dif ferent impact on
preparation judgments than on causal judgments.
Quarterly Journal of Experimental Psychology, 60,
Dickinson, A., Shanks, D. R., & Evenden, J. L. (1984).
Judgement of actoutcome contingency: The role of
selective attribution. Quarterly Journal of
Experimental Psychology, 36A, 2950.
Hagmayer, Y., & Waldmann, M. R. (2007). Inferences
about unobserved causes in human contingency
learning. Quarterly Journal of Experimental
Psychology, 60, 330355.
Karazinov, D. M., & Boakes, R. A. (2007). Second
order conditioning in human predictive judgements
when there is little time to think. Quarterly Journal
of Experimental Psychology, 60, 448460.
Miller, R. R., & Matute, H. (1996). Biological signifi-
cance in forward and backward blocking:
Resolution of a discrepancy between animal con-
ditioning and human causal judgment. Journal of
Experimental Psychology: General, 125, 370386.
Mitchell, C. J., Livesey, E., & Lovibond, P. F. (2007). A
dissociation between causal judgement and the ease
with which a cause is categorised with its effect.
Quarterly Journal of Experimental Psychology, 60,
Msetfi, R. M., Murphy, R. A., & Simpson, J. (2007).
Depressive realism and the effect of inter-trial-inter-
val on judgements of zero, positive and negative con-
tingencies. Quarterly Journal of Experimental
Psychology, 60, 461481.
o, O., & Miller, R. R. (2007). Comparing associ-
ative, statistical, and inferential reasoning accounts of
human contingency learning. Quarterly Journal of
Experimental Psychology, 60, 310329.
Shanks, D. R. (1985). Continuous monitoring of
human contingency judgment across trials. Memory
& Cognition, 13
, 158167.
Shanks, D. R. (1986). Selective attribution and the
judgment of causality. Learning and Motivation, 17,
Shanks, D. R. (1987). Acquisition functions in contin-
gency judgment. Learning and Motivation, 18,
Shanks, D. R. (2007). Associationism and cognition:
Human contingency learning at 25. Quarterly
Journal of Experimental Psychology, 60, 291309.
Vadillo, M. A., & Matute, H. (2007). Predictions and
causal estimations are not supported by the same
associative structure. Quarterly Journal of
Experimental Psychology, 60, 433447.
Vandorpe, S., De Houwer, J., & Beckers, T. (2007).
Outcome maximality and additivity training also
influence cue competition in causal learning
when learning involves many cues and events.
Quarterly Journal of Experimental Psychology, 60,
... For any intelligent organism to be able to understand and interact effectively with its environment, it is necessary to learn the regularities between events and outcomes (Allan, 2005;Beckers, De Houwer, & Matute, 2007;Shanks, 2010). Knowledge of the meaning of words, the tastes of foods, and the likely results of our actions are all built on this contingency learning backbone. ...
Full-text available
We explore the development of habitual responding within the colour-word contingency learning paradigm, in which participants respond to the colour of neutral words. Each word is most often presented in one colour. Learning is indicated by faster responses to the colour when the word is presented in the expected rather than in the unexpected colour. In Experiment 1, participants took part in two sessions, separated by one day. Critically, one set of words was trained across both days, and other new sets of words were introduced at various time points. Overall performance was faster on trials with overtrained words. Additionally, contingency effects were larger for overtrained words than for words introduced on Day 2. Removing the contingency had a similar impact on the learning effect for overtrained and new words. However, during a counterconditioning phase, where the words were made predictive of new colours, the previous contingency continued to influence performance for overtrained words but not for more recently introduced words. Relatedly, the new contingency was not acquired for the overtrained words. The reverse pattern was observed for recently-introduced words, with the newly-introduced contingency rapidly acquired and the influence of the old contingency quickly extinguished. In Experiments 2 and 3, however, both new and old learning effects were observed for both overtrained and recently-acquired contingencies. The net results suggest that while contingency learning effects are highly pliable during initial and subsequent learning, early-acquired contingency knowledge is maintained after removal of the contingency. Implications for models of learning are discussed.
... Contingency learning involves acquiring knowledge that two events tend to occur together (e.g., the presentation of the word RED typically requires the response "green") and using that knowledge to facilitate responding (Beckers, De Houwer, & Matute, 2007). In color-word identification tasks in which the words used are not color names, contingency learning is presumed to explain why color identification is faster for a frequent word-color pair (= highcontingency item, e.g., the word BRAG presented in green color 75% of the time) than for an infrequent word-color pair (= low-contingency item, e.g., the word BRAG presented in yellow color 25% of the time) (Schmidt et al., 2007; see also . ...
Full-text available
In the Stroop task, smaller congruency effects (i.e., the color-naming difference between incongruent items, e.g., the word RED in the color blue, and congruent items, e.g., RED in red) are found in conditions in which incongruent items are frequent vs. infrequent. Although the traditional explanation for these “Proportion-Congruent effects” is that attention to task-relevant information is more focused in frequently-conflicting conditions (a process involving adaptation to conflict frequency), Proportion-Congruent paradigms typically have not controlled for the impact of more general learning processes, particularly 1) learning of word-response contingencies (contingency learning), 2) learning about the predictive nature of the stimuli (stimulus informativeness), and 3) learning about response rhythm in the task (temporal learning), processes which could produce the Proportion-Congruent effects obtained in most situations. The present research examined the possibility that those non-conflict learning processes are indeed the whole story in Proportion-Congruent effects. Several different approaches were used. First, the proportion of congruent and incongruent items in a list was manipulated in a variant of the Stroop task in which no individual stimulus was repeated, creating a situation in which neither contingency learning nor stimulus informativeness could have influenced task performance. Second, manipulating the proportion of neutral (i.e., consonant strings) and incongruent items in a list allowed the creation of a parallel situation in the classic color-word Stroop task. A Proportion-Congruent effect and a similar, Proportion-Neutral effect, emerged in both tasks even though contingency learning and stimulus informativeness could have played no role in producing those effects. Further, attempts to examine the influence of temporal learning failed to show any evidence of that process contributing to those effects either. The final set of experiments involved a congruency-proportion manipulation specific to individual words within the same list. Contrary to the idea that the Proportion-Congruent effect obtained in this situation results from contingency learning, a concurrent working memory load impaired contingency learning in a non-conflict color identification task but spared the Proportion-Congruent effect in the Stroop task, favoring a conflict-adaptation interpretation of this effect. Overall, these results support the existence of a process of adaptation to conflict frequency in the human control system.
... One of the basic requirements of the human cognitive system, if not the most basic, is our ability to learn regularities between events in our environment (Allan, 2005;Beckers, De Houwer, & Matute, 2007;Shanks, 2010). Contingency learning is the basic building block for causal learning, knowledge acquisition, and the formation of the expectancies that make our world feel ordered rather than chaotic. ...
Full-text available
The learning of contingent regularities between events is fundamental for interacting with our world. We are also heavily influenced by recent experiences, as frequently studied in the stimulus-response (S-R) binding literature. According to one view ("unitary view"), the learning of regularities across many events and the influence of recent events on current performance can coherently be explained with one high-learning rate memory mechanism. That is, contingency learning effects and binding effects are essentially the same thing, only studied at different time scales. On the other hand, there may be more to a contingency effect than just the summation of the influence of past events (e.g., an additional impact of learned regularities). To test these possibilities, the current report reanalyzes a number of datasets from the colour-word contingency learning paradigm. It is shown that the weighted sum of binding effects accumulated across many previous trials (with especially strong influence of very recent events) does explain a large chunk of the contingency effect, but not all of it. In particular, the asymptote toward which the contingency effect decreases by accounting for an increasing number of previous-trial binding effects is robustly above zero. On the other hand, we also observe evidence for higher-order interactions between binding effects at differing lags, suggesting that a mere linear accumulation of binding episodes might underestimate their influence on contingency learning. Accordingly, focusing only on episodic S-R binding effects that are due to the last occurrence of a stimulus rendered contingency learning effects non-significant. Implications for memory models are discussed.
... One of the basic requirements of the human cognitive system, if not the most basic, is our ability to learn regularities between events in our environment (Allan, 2005;Beckers, De Houwer, & Matute, 2007;Shanks, 2010). Contingency learning is the basic building block for causal learning, knowledge acquisition, and the formation of the expectancies that make our world feel ordered rather than chaotic. ...
... Contingency learning involves acquiring knowledge that two events tend to occur together (e.g., the presentation of the word RED typically requires the response "green") and using that knowledge to facilitate responding (Beckers, De Houwer, & Matute, 2007). In color-word identification tasks in which the words used are not color names, contingency learning is presumed to explain why color identification is faster for a frequent word-color pair (ϭ high-contingency item, e.g., the word BRAG presented in green color 75% of the time) than for an infrequent word-color pair (ϭ low-contingency item, e.g., the word BRAG presented in yellow color 25% of the time; Schmidt et al., 2007; see also Musen & Squire, 1993). ...
Full-text available
In interference tasks (e.g., Stroop, 1935), the difference between congruent and incongruent latencies (i.e., the "congruency" effect) is larger in trial blocks containing mostly congruent trials than in trial blocks containing mostly incongruent trials (the proportion-congruent [PC] effect). Although the PC effect has typically been interpreted as reflecting adjustments in attention toward/away from the task-irrelevant dimension (i.e., a conflict-adaptation strategy), recent research has suggested alternative accounts based on the learning of either contingencies (i.e., distractor-response associations) or of temporal expectancies (i.e., the typical response speed on previous trials), accounts in which conflict adaptation plays no role. Using the picture-word interference paradigm, we report data from two PC manipulations in which contingency learning was made impossible by using nonrepeated distractors (Experiment 1A) or both nonrepeated distractors and responses (Experiment 1B). The classic PC effect emerged in both experiments. In addition, learning of temporal expectancies could not explain the present PC effects either, as results from trial-level analyses of Experiments 1A and 1B and a nonconflict version of Experiment 1B (Experiment 2) were inconsistent with the predictions of the temporal learning account of PC effects. These results suggest that conflict adaptation remains a credible explanation for PC effects. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
... To interact successfully with the world around us, it is necessary to be able to learn the contingent regularities between events (Allan, 2005;Beckers, De Houwer, & Matute, 2007;De Houwer & Beckers, 2002). Whether learning to speak a language, to master a sport, or to take one's first steps, learning how one event produces another is critical for progression. ...
Full-text available
In the typical colour-word contingency learning paradigm, participants respond to the print colour of words where each word is presented most often in one colour. Learning is indicated by faster and more accurate responses when a word is presented in its usual colour, relative to another colour. To eliminate the possibility that this effect is driven exclusively by the familiarity of item-specific word-colour pairings, we examine whether contingency learning effects can be observed also when colours are related to categories of words rather than to individual words. To this end, the reported experiments used three categories of words (animals, verbs, and professions) that were each predictive of one colour. Importantly, each individual word was presented only once, thus eliminating individual color-word contingencies. Nevertheless, for the first time, a category-based contingency effect was observed, with faster and more accurate responses when a category item was presented in the colour in which most of the other items of that category were presented. This finding helps to constrain episodic learning models and sets the stage for new research on category-based contingency learning.
We propose a method that models unidirectional, contingency-based association scale ΔP in order to analyse the different degrees of morpheme productivity in apparently identical L1–L2 inflected pairs. The method has the potential to uncover differences in how in L1–L2 inflected items are represented by L2 learners and native speakers. Such differences are at risk of remaining invisible if one considers only frequency, distribution and rank of predicates.
Full-text available
This article suggests a method to appraise L2 morphemes productivity in longitudinal learner data. Traditionally, morpheme productivity is believed to depend on type frequency and on proportion between inflected and uninflected lexemes. However, such measures cannot distinguish between rote-learning and rule-learning of target-like forms. In contrast, the association measure Δ P (delta pi) can quantify the extent to which a morpheme is contingent upon a limited number of lexemes. Decreasing contingency might parallel learners’ increasing awareness of asymmetrical morpheme-lexeme distribution in the input and this might be a cue of developing L2 grammatical competence beyond appearances. The paper presents the rationale and procedure for analyzing within-item variance – or the ‘intra-language’ – and illustrates a case-study concerning the perfective morpheme in L2 Italian.
Full-text available
This study utilized unidirectional association score Δ P to track perfective morpheme productivity in longitudinal spoken L2 Italian data. Research questions concerned whether early L2 perfectives were contingent upon telicity of predicates, whether lexeme–morpheme association changed as proficiency increased, and whether distribution of perfectives in the L1 input affected the patterns of morpheme emergence. Results showed that (i) the productive use of the perfective was contingent upon a few, infrequent telic predicates but also upon some actionally underspecified, very frequent general-purpose ones; (ii) a generalized decrease in association scores over time accompanied the productivity of the perfective morpheme; (iii) distribution of perfectives in L2 data did not reflect distribution in the L1 input. The statistical analysis adopted in this study is replicable to other domains where contingency of stem-affix alternations may provide cues for observing the developing L2 grammar
Full-text available
Similarities between Pavlovian conditioning in nonhumans and causal judgment by humans suggest that similar processes operate in these situations. Notably absent among the similarities is backward blocking (i.e., retrospective devaluation of a signal due to increased valuation of another signal that was present during training), which has been observed in causal judgment by humans but not in Pavlovian responding by animals. The authors used rats to determine if this difference arises from the target cue being biologically significant in the Pavlovian case but not in causal judgment. They used a sensory preconditioning procedure in Experiments 1 and 2, in which the target cue retained low biological significance during the treatment, and obtained backward blocking. The authors found in Experiment 3 that forward blocking also requires the target cue to be of low biological significance. Thus, low biological significance is a necessary condition for a stimulus to be vulnerable to blocking.
Full-text available
Forward blocking is one of the best-documented phenomena in Pavlovian animal conditioning. According to contemporary associative learning theories, forward blocking arises directly from the hardwired basic learning rules that govern the acquisition or expression of associations. Contrary to this view, here the authors demonstrate that blocking in rats is flexible and sensitive to constraints of causal inference, such as violation of additivity and ceiling considerations. This suggests that complex cognitive processes akin to causal inferential reasoning are involved in a well-established Pavlovian animal conditioning phenomenon commonly attributed to the operation of basic associative processes.
Full-text available
In one form of a contingency judgement task individuals must judge the relationship between an action and an outcome. There are reports that depressed individuals are more accurate than are non-depressed individuals in this task. In particular, nondepressed individuals are influenced by manipulations that affect the salience of the outcome, especially outcome probability. They overestimate a contingency if the probability of an outcome is high--the "outcome-density effect". In contrast, depressed individuals display little or no outcome-density effect. This apparent knack for depressives not to be misled by outcome density in their contingency judgements has been termed "depressive realism", and the absence of an outcome-density effect has led to the characterization of depressives as "sadder but wiser". We present a critical summary of the depressive realism literature and provide a novel interpretation of the phenomenon. We suggest that depressive realism may be understood from a psychophysical analysis of contingency judgements.
Full-text available
In three experiments we tested how the spacing of trials during acquisition of zero, positive, and negative response-outcome contingencies differentially affected depressed and nondepressed students' judgements. Experiment 1 found that nondepressed participants' judgements of zero contingencies increased with longer intertrial intervals (ITIs) but not simply longer procedure durations. Depressed groups' judgements were not sensitive to either manipulation, producing an effect known as depressive realism only with long ITIs. Experiments 2 and 3 tested predictions of Cheng's (1997) Power PC theory and the Rescorla-Wagner (1972) model, that the increase in context exposure experienced during the ITI might influence judgements most with negative contingencies and least with positive contingencies. Results suggested that depressed people were less sensitive to differences in contingency and contextual exposure. We propose that a context-processing difference between depressed and nondepressed people removes any objective notion of "realism" that was originally employed to explain the depressive realism effect (Alloy & Abramson, 1979).
Full-text available
Studies performed by different researchers have shown that judgements about cue-outcome relationships are systematically influenced by the type of question used to request those judgements. It is now recognized that judgements about the strength of the causal link between a cue and an outcome are mostly determined by the cue-outcome contingency, whereas predictions of the outcome are more influenced by the probability of the outcome given the cue. Although these results make clear that those different types of judgement are mediated by some knowledge of the normative differences between causal estimations and outcome predictions, they do not speak to the underlying processes of these effects. The experiment presented here reveals an interaction between the type of question and the order of trials that challenges standard models of causal and predictive learning that are framed exclusively in associative terms or exclusively in higher order reasoning terms. However, this evidence could be easily explained by assuming the combined intervention of both types of process.
In the first experiment subjects were presented with a number of sets of trials on each of which they could perform a particular action and observe the occurrence of an outcome in the context of a video game. The contingency between the action and outcome was varied across the different sets of trials. When required to judge the effectiveness of the action in controlling the outcome during a set of trials, subjects assigned positive ratings for a positive contingency and negative ratings for a negative contingency. Furthermore, the magnitude of the ratings was related systematically to the strength of the actual contingency. With a fixed probability of an outcome given the action, judgements of positive contingencies decreased as the likelihood that the outcome would occur without the action was raised. Correspondingly, the absolute value of ratings of negative contingencies was increased both by an increment in the probability of the outcome in the absence of the action and by a decrement in the probability of the outcome following the action. A systematic bias was observed, however, in that positive judgements were given under a non-contingent relationship when the outcome frequency was relatively high. However, this bias could be reduced by giving extended exposure to the non-contingent schedule (Experiment 2). This pattern of contingency judgements can be explained if it is assumed that a process of selective attribution operates, whereby people are less likely to attribute an outcome to some potential target cause if another effective cause is present. Experiments 2 and 3 demonstrated the operation of this process by showing that initially establishing another agent as an effective cause of the outcome subsequently reduced or blocked the extent to which the subjects attributed the outcome to the action. Finally, we argue that the pattern and bias in contingency judgements based upon interactions with a causal process can be explained in terms of contemporary conditioning models of associative learning.
Four experiments used a video game procedure to investigate the mechanism by which people are sensitive to the degree of contingency between two events. Subjects were presented with sets of trials on each of which they could perform a particular action and observe whether the action produced a particular outcome in a situation in which there was an alternative potential cause of the outcome. The experiments attempted to show that the process of selective attribution operates during exposure to a particular contingency and mediates the contingency judgment. In Experiment 1 the impact of outcomes occurring in the absence of the action was reduced by changing the location at which outcomes occurred following the action. Experiment 2 replicated this effect and showed that it was not due to simple changes in temporal contiguity, but rather was due to affecting the process of selective attribution. In Experiment 3 judgments were shown to increase when outcomes occurring in the absence of the action, outcomes which otherwise would reduce judgments of action-outcome contingency, were signaled. Finally, in Experiment 4 this effect was replicated, and in addition it was shown that the signaling effect is not simply due to the presence of the signal. For the effect to be shown, the signal must occur when the outcome occurs in the absence of the action.
Two experiments investigated the way in which judgments of the extent to which an action caused an outcome changed as more experience of the actionoutcome contingency was presented. In the first experiment judgments increased across trials when there was a positive contingency and decreased when there was a negative contingency. In noncontingent situations judgments were biased by the overall probability of the outcome. In the second experiment the changes across trials under positive and negative contingencies persisted even when the subjects were given the opportunity to dissociate their causality judgments from their degree of confidence in those judgments. The results are at variance with the dP and dD theories which attempt to account for causality judgments in terms of statistical rules based on the probabilities or frequencies of the relevant events. If such theories were modified, however, to take account of the regression of the subjects' estimates onto the actual probabilities or frequencies, then the data could be accommodated. On the other hand, a simple associative view is also able to account for the data.
Recent evidence suggests that people are sensitive to the degree of contingency between their actions and ensuing outcomes, but little is known about the way in which such contingency judgments develop as more and more information about the contingency is provided. Three experiments examined this issue in the context of a video game. In Experiment 1, it was found that contingency judgments follow growth functions: When the contingency was positive, judgments increased toward a positive asymptote, and when the contingency was negative, judgments decreased toward a negative asymptote. When the contingency was zero, judgments themselves remained close to zero but were biased by the overall frequency with which the outcome occurred. In Experiment 2, it was shown that the growth function was not the result of the anchoring of early judgments at the zero point. The bias in judgments when the contingency is zero was investigated in Experiment 3. The results are discussed in terms of rule-based analyses and contemporary theories of conditioning.
Associative accounts uniquely predict that second-order conditioning might be observed in human predictive judgements. Such an effect was found for cue X in two experiments in which participants were required to predict the outcomes of a series of training trials that included P + and PX-, but only when training was paced by requiring participants to make a prediction within 3 s on each trial. In Experiment 1 training on P + ended before training was given on PX - . In Experiment 2 trials with P+, PX-, T + and other cues were intermixed. In the unpaced group inhibitory learning was revealed by a summation test, TX versus TM, where M was a control stimulus. These results suggest either that pacing interferes with learning successive associations more than with learning simultaneous associations or that lack of time to think interferes with inferential processes required for this type of inhibitory learning.