Instruction on the Scientific Method Provides (Some) Protection Against Illusions of Causality.

People tend to overestimate the efficacy of an ineffective treatment when they experience the treatment and its supposed outcome co-occurring frequently. This is referred to as the outcome density effect. Here, we attempted to improve the accuracy of participants' assessments of an ineffective treatment by instructing them about the scientific practice of comparing treatment effects against a relevant base-rate, i.e., when no treatment is delivered. The effect of these instructions was assessed in both a trial-by-trial contingency learning task, where cue administration was either decided by the participant (Experiments 1 & 2) or pre-determined by the experimenter (Experiment 3), as well as in summary format where all information was presented on a single screen (Experiment 4). Overall, we found two means by which base-rate instructions influence efficacy ratings for the ineffective treatment: 1) When information was presented sequentially, the benefit of base-rate instructions on illusory belief was mediated by reduced sampling of cue-present trials, and 2) When information was presented in summary format, we found a direct effect of base-rate instruction on reducing causal illusion. Together, these findings suggest that simple instructions on the scientific method were able to decrease participants' (over-)weighting of cue-outcome coincidences when making causal judgements, as well as decrease their tendency to over-sample cue-present events. However, the effect of base-rate instructions on correcting illusory beliefs was incomplete, and participants still showed illusory causal judgements when the probability of the outcome occurring was high. Thus, simple textual information about assessing causal relationships is partially effective in influencing people's judgements of treatment efficacy, suggesting an important role of scientific instruction in debiasing cognitive errors.

Contingency inferences from base rates: A parsimonious strategy?

The pseudocontingency framework provides a parsimonious strategy for inferring the contingency between two variables by assessing the base rates. Frequently occurring levels are associated, as are rarely occurring levels. However, this strategy can lead to different contingency inferences in different contexts, depending on how the base rates vary across contexts. Here, we examine how base-rate consistency influences base-rate learning and reliance by contrasting consistent with inconsistent base rates. We hypothesized that base-rate learning is facilitated, and that people rely more on base rates if base rates are consistent. In Experiment 1, the base rates across four contexts implied the same (consistent) or different (inconsistent) contingencies. Base rates were learned equally accurately, and participants inferred contingencies that followed the base rates but deviated from the genuine contingencies within contexts, regardless of consistency. In Experiment 2, we additionally manipulated whether the context was a plausible moderator of the contingency. While we replicated the first experiment's results when the context was a plausible moderator, base-rate inferences were stronger for consistent base rates when the context was an implausible moderator. Possibly, when a moderation-by-context was implausible, participants also relied on the base-rate correlation across contexts, which implied the same contingency when base rates were consistent but was zero when the base rates were inconsistent. Thus, our findings suggest that contingency inferences from base rates involve top-down processes in which people decide how to use base-rate information.

Release from response interference in color-word contingency learning.

In identifying the print colors of words when some combinations of color and word occur more frequently than others, people quickly show evidence of learning these associations. This contingency learning effect is evident in faster and more accurate responses to high-contingency combinations than to low-contingency combinations. Across four experiments, we systematically varied the number of response-irrelevant word stimuli connected to response-relevant colors. In each experiment, one group experienced the typical contingency learning paradigm with three colors linked to three words; other groups saw more words (six or twelve) linked to the same three colors. All four experiments disconfirmed a central prediction derived from the Parallel Episodic Processing (PEP 2.0) model (Schmidt et al., 2016)-that the magnitude of the contingency learning effect should remain stable as more words are added to the response-irrelevant dimension, as long as the color-word contingency ratios are maintained. Responses to high-contingency items did slow down numerically as the number of words increased between groups, consistent with the prediction from PEP 2.0, but these changes were unreliable. Inconsistent with PEP 2.0, however, overall response time did not slow down and responses to low-contingency items actually sped up as the number of words increased across groups. These findings suggest that the PEP 2.0 model should be modified to incorporate response interference caused by high-probability associations when responding to low-probability combinations.

How evaluative pairings improve body dissatisfaction in adult women: evidence from a randomized-controlled online study.

BACKGROUND: Many young women are dissatisfied with their bodies. This study investigated the effect on current body dissatisfaction levels of a newly developed evaluative conditioning procedure that paired self-similar and self-dissimilar images of bodies with positive and neutral affective images, respectively. We hypothesized that learning the contingency that self-similar bodies predict positive affectivity is one process that could aid in explaining how these procedures function. METHODS: Adult women without disordered eating pathology participated in an online experiment with random assignment to an intervention or a control condition. All participants initially rated body images in self-similarity and were subsequently asked to categorize positive and neutral images by valence as quickly and accurately as possible. In the intervention condition, self-similar bodies systematically preceded positive images, and self-dissimilar images preceded neutral images, creating a similar body → positive contingency. Pairings in the control condition were unsystematic such that no contingency was present. We measured categorization latencies and accuracies to infer contingency learning as well as current body dissatisfaction immediately before and after exposure to the pairings. All participants further completed measures of trait body image concerns and disordered eating psychopathology at baseline, which we examined as moderators of an expected relation between condition assignment, contingency learning, and body dissatisfaction improvements. RESULTS: We analyzed data from N = 173 women fulfilling the inclusion criteria. Moderated mediation analyses showed that assignment to the intervention (vs. control) condition predicted increased similar body → positive contingency learning, which in turn predicted improved body dissatisfaction post-intervention, but only among women with higher pre-existing trait body image concerns or disordered eating levels. CONCLUSIONS: The findings point toward the relevancy of further exploring the utility of pairing procedures. Similar body → positive contingency learning predicted improved body dissatisfaction in individuals with normatively high body image concerns, which suggests pairing procedures could help inform future research on reducing body dissatisfaction.

Many people are dissatisfied with how their bodies look or how much they weigh. Body dissatisfaction can increase the risk of developing an eating disorder. This study tested a method for reducing body dissatisfaction among women. The method included pairing pictures of bodies judged as similar to one's own body with positive pictures. For one half of the study participants, we arranged the pairings in a way that one could systematically learn that similar body pictures and positive pictures go together. Compared to the other half of study participants who were shown pairings by chance, we found that study participants indeed learned that similar body pictures and positive pictures go together. Moreover, this learning made participants who were generally dissatisfied with their bodies or who reported disordered eating symptoms more satisfied with their bodies immediately after the procedure. These findings suggest that the method could be further developed, investigated, and used in treating or preventing eating disorders.

One Link to Link Them All.

A conditioned response to a stimulus can be transferred to an associated stimulus, as seen in sensory preconditioning. In this research paper, we aimed to explore this phenomenon using a stimulus-response contingency learning paradigm using voluntary actions as responses. We conducted two preregistered experiments that explored whether a learned response can be indirectly activated by a stimulus (S1) that was never directly paired with the response itself. Importantly, S1 was previously associated with another stimulus (S2) that was then directly and contingently paired with a response (S2-R contingency). In Experiment 1a, an indirect activation of acquired stimulus-response contingencies was present for audiovisual stimulus pairs wherein the stimulus association resembled a vocabulary learning setup. This result was replicated in Experiment 1b. Additionally, we found that the effect is moderated by having conscious awareness of the S1-S2 association and the S2-R contingency. By demonstrating indirect activation effects for voluntary actions, our findings show that principles of Pavlovian conditioning like sensory preconditioning also apply to contingency learning of stimulus-response relations for operant behavior.

Unidirectional rating scales overestimate the illusory causation phenomenon.

Illusory causation is a phenomenon in which people mistakenly perceive a causal relationship between a cue and outcome even though the contingency between them is actually zero. Illusory causation studies typically use a unidirectional causal rating scale, where one endpoint refers to no relationship and the other to a strongly positive causal relationship. This procedure may bias mean causal ratings in a positive direction, either by censoring negative ratings or by discouraging participants from giving the normative rating of zero which is at the bottom extreme of the scale. To test this possibility, we ran two experiments that directly compared the magnitude of causal illusions when assessed with a unidirectional (zero-positive) versus a bidirectional (negative-zero-positive) rating scale. Experiment 1 used high cue and outcome densities (both 75%), whereas Experiment 2 used neutral cue and outcome densities (both 50%). Across both experiments, we observed a larger illusory causation effect in the unidirectional group compared with the bidirectional group, despite both groups experiencing the same training trials. The causal illusions in Experiment 2 were observed despite participants accurately learning the conditional probabilities of the outcome occurring in both the presence and absence of the cue, suggesting that the illusion is driven by the inability to accurately integrate conditional probabilities to infer causal relationships. Our results indicate that although illusory causation is a genuine phenomenon that is observable with either a undirectional or a bidirectional rating scale, its magnitude may be overestimated when unidirectional rating scales are used.

Associative interference and nonreinforcement in human contingency learning.

This article reports three experiments comparing the impact on contingency assessment of associative cue interference (proactive, interspersed, and retroactive) and nonreinforcement (latent inhibition, partial reinforcement, and extinction). All three experiments used variants of the rapid trial streaming procedure developed by Allan and collaborators. Participants were exposed to stimulus streams and then asked how likely it was for a target cue to be accompanied (Experiment 1) or to be followed (Experiments 2 and 3) by a target outcome. Experiments 1 and 2 looked at interference and found that when the objective target cue-outcome contingency is positive, interspersed interference is more effective than either proactive or retroactive interference. Experiment 2 additionally showed that this conclusion was a function of the target cue-outcome contingency: when the number of cue-outcome pairings was low, retroactive interference was more efficient than interspersed interference. Experiment 3 examined nonreinforcement and found that the efficacies of latent inhibition, partial reinforcement, and extinction are also a function of the target cue-outcome contingency, but the pattern differed greatly from what was observed in Experiment 2. When the number of cue-outcome pairings was high, there was no difference between latent inhibition, partial reinforcement, and extinction. When the number of cue-outcome pairings was low, extinction did not lower the contingency judgement, whereas latent inhibition and partial reinforcement did.

Proactive control affects task conflict beyond contingency learning.

Various models of the Stroop task suggest that proactive task control adaptation accounts for the modulation of task conflict in different conditions of the Stroop task, for example, when task conflict is very frequent or very infrequent. Other researchers have argued that a contingency learning of colour-word associations is the main contributor to the modulations of the Stroop effect. In this work, we constructed a design that controls for confounds that are suspected to rule out the role of control adaptation in the Stroop task. We focused on one type of conflict-task conflict and tested whether colour-naming of neutral-words (where task conflict is present) differed from colour-naming of neutral-symbols (where task conflict is not present) in four different conditions: mostly words-congruent, mostly words-incongruent, mostly words-neutral, or mostly non-words-shape. Importantly, the conditions used for the task conflict marker were identical in all four conditions. We found that the marker of task conflict (reaction time [RT] for neutral-words > RT for neutral-symbols) was significant in the mostly non-words-shape condition, where proactive task control is relaxed, but not in the mostly words conditions, where proactive task control is activated, with no difference between these three words conditions. These findings suggest that control adaptation is the main contributor to the modulations of the Stroop effect. The relevance of the results to the current literature is discussed and the results are explained in light of the proactive control-task conflict (PC-TC) model.

Contingency learning and episodic contributions to the item-specific proportion congruent effect.

Several studies have challenged the conflict adaptation account of cognitive control effects, suggesting that they are the result of learning/memory processes independent from control modulation. Some authors have suggested that the item-specific proportion congruent (ISPC) effect (i.e., the smaller congruency effect on items presented frequently in an incongruent combination) is driven by colour-word contingency learning (CL). However, it has recently been suggested that CL can be explained in terms of episodic retrieval of the response given to the last encounter with the same stimulus, with no role of associative learning. This study aims to analyse the independent role of CL and episodic retrieval on the ISPC effect. Experiment 1 showed no effect of control modulation and indicated that, when manipulated independently, learning-driven contingency is modulated by the episodic factor, but it remains significant. Experiments 2 and 3 extended the study of the interplay between learning and recency to the colour-word CL paradigm, finding larger contingency effects on colour words compared with neutral ones and replicating the interaction between CL and episodic retrieval from Experiment 1. Surprisingly, these two experiments also showed control modulation apart from contingency and recency effects in colour words. In sum, our study reveals that the ISPC effect results from the joint contribution of cognitive control, associative learning, and episodic effects.

Target-distractor correlation does not imply causation of the Stroop effect.

In the Stroop task, the identities of the targets (e.g., colours) and distractors (e.g., words) used are often correlated. For example, in a list in which 4 words and 4 colours are combined to form 16 stimuli, each of the 4 congruent stimuli is typically repeated 3 times as often as each of the 12 incongruent stimuli. Some accounts of the Stroop effect suggest that in this type of list, often considered as a baseline because of the matching proportion of congruent and incongruent stimuli (50%), the word dimension actually receives more attention than it does in an uncorrelated list in which words and colours are randomly paired. This increased attention would be an important determinant of the Stroop effect in correlated situations, an idea supported by the observation that higher target-distractor correlation lists are associated with larger Stroop effects. However, because target-distractor correlation tends to be confounded with congruency proportion in common designs, the latter may be the crucial factor, consistent with accounts that propose that attention is adapted to the list's congruency proportion. In four experiments, we examined the idea that target-distractor correlation plays a major role in colour-word Stroop experiments by contrasting an uncorrelated list with a correlated list matched on relevant variables (e.g., congruency proportion). Both null hypothesis significance testing and Bayesian analyses suggested equivalent Stroop effects in the two lists, challenging accounts based on the idea that target-distractor correlations affect how attention is allocated in the colour-word Stroop task.

Learning of irrelevant stimulus-response associations modulates cognitive control.

It has been shown that manipulating the proportion of congruent to incongruent trials in conflict tasks (e.g., Stroop, Simon, and flanker tasks) can vary the size of conflict effects, however, by two different mechanisms. One theory is the control learning account (the brain learns the probability of conflict and uses it to proactively adjust the control demand for future trials). The other is the irrelevant stimulus-response learning account (the brain learns the probability of irrelevant stimulus-response associations and uses it to prepare responses). Previous fMRI studies have detected the brain regions that contribute to the control-learning-modulated conflict effects, but it is less known what neural substrates underlie the conflict effects modulated by irrelevant S-R learning. We here investigated this question with a model-based fMRI study, in which the proportion of congruent to incongruent trials changed dynamically in the Simon task and the models learned the probability of irrelevant S-R associations quantitatively. Behavioral analyses showed that the unsigned prediction errors (PEs) of responses generated by the learning models correlated with reaction times irrespective of congruent and incongruent trials, indicating that large unsigned PEs associated with slow responses. The fMRI results showed that the regions of fronto-parietal and cingulo-opercular network involved in cognitive control were significantly modulated by the unsigned PEs, also irrespective of congruent and incongruent trials, indicating that large unsigned PEs associated with transiently increased activity in these regions. These results together suggest that learning of irrelevant S-R associations modulates reactive control, which demonstrates a new way to modulate cognitive control compared to the control learning account.

Interpretation of ambiguous trials along with reasoning strategy is related to causal judgements in zero-contingency learning.

The dual strategy model suggests that people can use either a Statistical or a Counterexample reasoning strategy, which reflects two qualitatively different ways of processing information. This model has been shown to capture individual differences in a wide array of tasks, such as contingency learning. Here, we examined whether this extends to individual differences in the interpretation of contingency information where effects are ambiguous. Previous studies, using perceptually complex stimuli, have shown that the way in which participants interpret ambiguous effects predicts causal judgements. In two studies, we attempted to replicate this effect using a small number of clearly identifiable cues. Results show that the interpretation of ambiguous effects as effect present is related to final contingency judgements. In addition, results showed that Statistical reasoners had a stronger tendency to interpret ambiguous effects as effect present than Counterexample reasoners, which mediates the difference in contingency judgements.

Planning on Autopilot? Associative Contributions to Proactive Control.

Proactive cognitive control is thought to rely on the active maintenance of goals or contextual information in working memory. It is often measured using the AX-CPT, in which antecedent cues (A/B) are used to proactively prepare a response to a subsequently-presented probe (X/Y). Although control in this task purportedly requires active maintenance of information in working memory, it also provides conditions in which learning the contingencies between relevant events could influence performance via associative learning. We tested this hypothesis using a dot-pattern expectancy version of the AX-CPT whereby a set of new rules (test phase) for responding changed the control operations required for some previously trained cues, while keeping the operations the same for others, allowing us to measure associative interference. We also tested the relationship between associative interference and working memory capacity (operation span; Experiments 1-3) and tested the effect of applying working memory load during the initial acquisition period (Experiment 2) and during the test phase (Experiment 3). We found robust evidence of interference after the rule change based on previously learnt contingencies, suggesting that learnt contingencies come to influence proactive planning, even when they are task-irrelevant. This associative effect had no relationship with working memory capacity or load, based on a load manipulation commonly used in executive control tasks. The findings suggest that proactive control does not always require active maintenance of current goals and environmental cues in working memory. Instead, proactive control may run on autopilot if the individual can rely upon stable relationships in the environment to trigger planning and preparation. SIGNIFICANCE: Navigating daily life requires us to anticipate future events and plan our thoughts and actions accordingly to achieve our goals. This forward planning, or proactive control, is thought to be a resource-intensive and metabolically costly process that recruits higher-order cognitive functions, such as working memory, where relevant thoughts and actions have to be maintained online. The current study challenged this notion by finding that proactive control can be incrementally relegated to simpler processes based on one's learning of stable relationships in the environment, thereby reducing the need to actively maintain information online. Individuals can come to rely on underlying contingencies in stimuli associated with proactive control, even when it is detrimental to their goals.

Incidental learning in music reading: The music contingency learning task.

The present report investigated whether nonmusicians can incidentally learn musical skills needed for sight-reading. On each trial, participants identified a note name written inside of a note on the musical staff. In Experiment 1, each note was presented frequently with the congruent note name (e.g., "do" with the note for "do") and rarely with the incongruent names (e.g., "do" with the note for "fa"). With or without deliberate learning instructions, a robust contingency learning effect was observed: faster responses for congruent trials compared with incongruent trials. Participants also explicitly identified the meaning of the note positions more accurately than chance. Experiment 2 ruled out the potential influence of preexisting knowledge on the contingency learning effect by presenting notes most often with an incongruent note name. Robust learning was again observed, suggesting that participants acquired sufficient knowledge of musical notation to produce automatic influences on behaviour (e.g., akin to the interference effect previously found in skilled musicians). A congruency effect was additionally observed in Experiment 2, however. Experiment 3 further explored to what extent this congruency effect might be due to prior music knowledge and/or spatial stimulus-response compatibility between note and response locations (analogous to the SMARC effect). Overall, our results open up new avenues for investigating the incidental learning of complex material, musical or otherwise, and for reinforcing learning even further.

Functional neuroanatomical correlates of contingency judgement.

Contingency judgement is an ability to detect relationships between events and is crucial in the allocation of attentional resources for reasoning, categorization, and decision making to control behaviour in our environment. Research has suggested that the allocation of attention is sensitive to the frequency of contingency information whether it constitutes a negative, zero or positive relationship. The aim of the present study was to explore the functional neuroanatomical correlates of contingency judgement with different frequencies and whether these are distinct from each other or whether they rely on a common mechanism. Using three contingency tasks within a streaming paradigm (one each for negative, zero, and positive contingency frequencies), we assessed brain activity by means of functional magnetic resonance imaging (fMRI) in 20 participants. Contingency frequency was manipulated between blocks which allowed us to determine the neural correlates of each of the three contingency tasks as well as the common areas of activation. The conjunction of task activation showed activity in left parietal cortices (BA 23, 40) and superior temporal gyrus (BA42). Further, the interaction analysis revealed distinct areas that mainly involve lateral (BA 45) and medial (BA 9) prefrontal cortices in the judgment of negative contingencies compared with positive and zero contingencies. We interpret the finding as evidence that the shared regions may be involved in coding, integration, and updating of associative relations and distinct regions may be involved in the investment of attentional resources to varied degrees in the computation of contingencies to make a judgment.

Being in the Know: The Role of Awareness and Retrieval of Transient Stimulus-Response Bindings in Selective Contingency Learning.

Previous studies demonstrated that contingency learning can be both (a) unaware (Schmidt et al., 2007), and (b) explained in terms of an automatic retrieval of stimulus-response bindings from the last episode in which the cue stimulus has been presented (Giesen et al., 2020; Schmidt et al., 2020). We investigated whether learning is selective in a contingency learning paradigm in which pairs of salient and nonsalient cues that were equally predictive of responses to targets (digits) were presented simultaneously. In two pre-registered experiments (total N = 137), we found stronger contingency learning for salient compared to non-salient cues. Transient stimulus-response binding and retrieval processes did not contribute to these selective learning effects in contingency learning, which were instead driven by contingency awareness. Our findings indicate that under conditions of high saliency, contingency learning is mediated by conscious rule detection for which retrieval of transient stimulus-response bindings is irrelevant.

Accounting for Proportion Congruency Effects in the Stroop Task in a Confounded Setup: Retrieval of Stimulus-Response Episodes Explains it All.

Proportion congruency (PC) effects on the strength of distractor interference were investigated in a high-powered (n = 109), pre-registered experiment in which participants had to identify the ink color of color words. Replicating the standard PC effect, Stroop interference was larger in blocks comprising mostly congruent word-color combinations, compared to blocks comprising mostly incongruent trials. These block-level differences in the strength of the Stroop effect were eliminated after controlling for (a) the congruency of the most recent episode in which the current word had been presented ("episodic retrieval of control states"), and also after controlling for (b) the response relation of this episode and the current trial ("episodic response retrieval"). Controlling for the congruency in trial n-1 (congruency sequence effect, CSE), irrespective of word relation did not eliminate the PC effect, nor did controlling for immediate exact and partial repetitions. When predicting PC effects simultaneously by both types of episodic retrieval processes, only episodic response retrieval explained the effect. Our findings attest to the importance of episodic response retrieval processes in explaining the PC effect in Stroop-like tasks in a confounded setup where different processes compete with each, and they speak against explanations in terms of a global adjustment of cognitive control settings or contingency learning under these conditions. The results further support the assumption that the most recent episode in which a stimulus had occurred is crucial for responding in the current trial (the "law of recency"; Giesen et al., 2020).

Proportion of conflict, contingency learning, and recency effects in a Stroop task.

Recent research on the relation between learning and cognitive control has assumed that conflict modulates learning, either by increasing arousal and hence improving learning in high-conflict situations, or by inducing control, and hence inhibiting the processing of distracters and their eventual association with the imperative responses. We analyse whether the amount of conflict, manipulated through the proportion of congruency in a set of Stroop inducer trials, affects learning of contingencies established on diagnostic trials composed by neutral words associated with colour responses. The results reproduced the list-wide proportion of congruency effect on the inducer trials, and showed evidence of contingency learning on the diagnostic trials, but provided no indication that this learning was modulated by the level of conflict. Specific analyses conducted to control for the impact of episodic effects on the expression of learning indicated that contingency effects were not driven by the incremental processes that could be expected by associative learning, but rather they were due to the impact of the most recent trial involving the same distracter. Accordingly, these effects disappeared when tested selectively on trials that required a non-matching response with respect to the previous occurrence of the distracter. We interpret this result in the context of the debate on how learning and memory interact with the processes of cognitive control.

Pseudoscientific Health Beliefs and the Perceived Frequency of Causal Relationships.

Beliefs about cause and effect, including health beliefs, are thought to be related to the frequency of the target outcome (e.g., health recovery) occurring when the putative cause is present and when it is absent (treatment administered vs. no treatment); this is known as contingency learning. However, it is unclear whether unvalidated health beliefs, where there is no evidence of cause-effect contingency, are also influenced by the subjective perception of a meaningful contingency between events. In a survey, respondents were asked to judge a range of health beliefs and estimate the probability of the target outcome occurring with and without the putative cause present. Overall, we found evidence that causal beliefs are related to perceived cause-effect contingency. Interestingly, beliefs that were not predicted by perceived contingency were meaningfully related to scores on the paranormal belief scale. These findings suggest heterogeneity in pseudoscientific health beliefs and the need to tailor intervention strategies according to underlying causes.

The role of contingency and correlation in the Stroop task.

Facilitation (faster responses to Congruent trials compared with Neutral trials) in the Stroop task has been a difficult effect for models of cognitive control to explain. The current research investigated the role of word-response contingency, word-colour correlation, and proportion congruency in producing Stroop effects. Contingency and correlation refers to the probability of specific word-response and word-colour pairings that are implicitly learnt while performing the task. Pairs that have a higher probability of occurring are responded to faster, a finding that challenges top-down attention control accounts of Stroop task performance. However, studies that try to experimentally control for contingency and correlation typically do so by increasing the proportion of incongruent trials in the task, which cognitive control accounts posit affects interference control via the top-down biasing of attention. The present research focused on whether facilitation is also affected by contingency and correlation while additionally looking at the effect of proportion congruency. This was done in two experiments that compared the typical design of Stroop task experiments (i.e., having equal proportions of Congruent and Incongruent trials but also contingency and correlational biases) to: (a) a design that had unequal congruency proportions but no contingency or correlation bias (Experiment 1) and (b) a design where the correlation is biased but proportion congruency and contingency were not (Experiment 2). Results did not support the hypotheses that contingency or correlation affected facilitation. However, interference was almost halved in the alternative design of Experiment 2, demonstrating an effect of contingency learning in typical measures of Stroop interference.