Proactive response preparation contributes to contingency learning: novel evidence from force-sensitive keyboards.

Contingency learning can involve learning that the identity of one stimulus in a sequence predicts the identity of the next stimulus. It remains unclear, however, whether such learning speeds responses to the next stimulus only by reducing the threshold for triggering the expected response after stimulus onset or also by preparing the expected response before stimulus onset. To distinguish between these competing accounts, we manipulated the probabilities with which each of two prime arrows (Left and Right) were followed by each of two probe arrows (Up and Down) in a prime-probe task while using force-sensitive keyboards to monitor sub-threshold finger force. Consistent with the response preparation account, two experiments revealed greater force just before probe onset on the response key corresponding to the direction in which the probe was more (versus less) likely to point (e.g., Up vs. Down). Furthermore, mirroring sequential contingency effects in behavior, this pre-probe force effect vanished after a single low-probability trial. These findings favor the response preparation account over the threshold only account. They also suggest the possibility that contingency learning in our tasks indexes trial-by-trial expectations regarding the utility of the prime for predicting the upcoming probe.

Interlinguistic conflict: Word-word Stroop with first and second language colour words.

The congruency (or Stroop) effect is a standard observation of slower and less accurate colour identification to incongruent trials (e.g. "red" in green) relative to congruent trials (e.g. "red" in red). This effect has been observed in a word-word variant of the task, when both the distracter (e.g. "red") and target (e.g. "green") are colour words. The Stroop task has also been used to study the congruency effect between two languages in bilinguals. The typical finding is that the congruency effect for L1 words is larger than that for L2 words. For the first time, the present report aims to extend this finding to a word-word variant of the bilingual Stroop task. In two experiments, French monolinguals performed a bilingual word-word Stroop task in which target word language, language match, and congruency between the distracter and target were manipulated. The critical manipulation across two experiments concerned the target language. In Experiment 1, target language was manipulated between groups, with either French (L1) or English (L2) target colour words. In Experiment 2, target words from both languages were intermixed. In both experiments, the congruency effect was larger when the distracter and target were from the same language (language match) than when they were from different languages (language mismatch). Our findings suggested that this congruency effect mostly depends on the language match between the distracter and target, rather than on a target language. It also did not seem to matter whether the language-mismatching distracter was or was not a potential response alternative. Semantic activation of languages in bilinguals and its implications on target identification are discussed.

The Use of Coffee to Decrease the Incidence of Postoperative Ileus: A Systematic Review and Meta-Analysis.

PURPOSE: To investigate the efficacy of providing coffee to elective abdominal surgery patients, immediately postoperatively, to lessen postoperative ileus. DESIGN: A systematic review with meta-analysis of six randomized controlled trials published since 2012. METHODS: Methodological quality was evaluated using the Cochrane guidelines. The Grading of Recommendations, Assessment, Development, and Evaluations assessment tool evaluated the quality of the evidence. Subgroup analyses were completed if the I2 statistic demonstrated heterogeneity (greater than 50%). FINDINGS: Coffee was statistically significant in shortening the time between surgery and the first passage of stool (mean difference, -9.38; 95% confidence interval, -17.60 to -1.16; P = .03). Although not statistically significant (P = .20), the overall effect favored shorter hospital stays for those patients receiving coffee. CONCLUSIONS: The current systematic review and meta-analysis suggests that coffee given as early as 2 hours postoperatively decreases time to first bowel movement. In addition, patients tolerated solid food faster and were discharged sooner when given coffee immediately postoperatively.

High salt diet impairs cerebral blood flow regulation via salt-induced angiotensin II suppression.

OBJECTIVES: This study sought to determine whether salt-induced ANG II suppression contributes to impaired CBF autoregulation. METHODS: Cerebral autoregulation was evaluated with LDF during graded reductions of blood pressure. Autoregulatory responses in rats fed HS (4% NaCl) diet vs LS (0.4% NaCl) diet were analyzed using linear regression analysis, model-free analysis, and a mechanistic theoretical model of blood flow through cerebral arterioles. RESULTS: Autoregulation was intact in LS-fed animals as MAP was reduced via graded hemorrhage to approximately 50 mm Hg. Short-term (3 days) and chronic (4 weeks) HS diet impaired CBF autoregulation, as evidenced by progressive reductions of laser Doppler flux with arterial pressure reduction. Chronic low dose ANG II infusion (5 mg/kg/min, i.v.) restored CBF autoregulation between the pre-hemorrhage MAP and 50 mm Hg in rats fed short-term HS diet. Mechanistic-based model analysis showed a reduced myogenic response and reduced baseline VSM tone with short-term HS diet, which was restored by ANG II infusion. CONCLUSIONS: Short-term and chronic HS diet lead to impaired autoregulation in the cerebral circulation, with salt-induced ANG II suppression as a major factor in the initiation of impaired CBF regulation.

Best not to bet on the horserace: A comment on Forrin and MacLeod (2017) and a relevant stimulus-response compatibility view of colour-word contingency learning asymmetries.

One powerfully robust method for the study of human contingency learning is the colour-word contingency learning paradigm. In this task, participants respond to the print colour of neutral words, each of which is presented most often in one colour. The contingencies between words and colours are learned, as indicated by faster and more accurate responses when words are presented in their expected colour relative to an unexpected colour. In a recent report, Forrin and MacLeod (2017b, Memory & Cognition) asked to what extent this performance (i.e., response time) measure of learning might depend on the relative speed of processing of the word and the colour. With keypress responses, learning effects were comparable when responding to the word and to the colour (contrary to predictions). However, an asymmetry appeared in a second experiment with vocal responses, with a contingency effect only present for colour identification. In a third experiment, the colour was preexposed, and contingency effects were again roughly symmetrical. In their report, they suggested that a simple speed-of-processing (or "horserace") model might explain when contingency effects are observed in colour and word identification. In the present report, an alternative view is presented. In particular, it is argued that the results are best explained by appealing to the notion of relevant stimulus-response compatibility, which also resolves discrepancies between horserace model predictions and participant results. The article presents simulations with the Parallel Episodic Processing model to demonstrate this case.

The Parallel Episodic Processing (PEP) model 2.0: A single computational model of stimulus-response binding, contingency learning, power curves, and mixing costs.

The current paper presents an extension of the Parallel Episodic Processing model. The model is developed for simulating behaviour in performance (i.e., speeded response time) tasks and learns to anticipate both how and when to respond based on retrieval of memories of previous trials. With one fixed parameter set, the model is shown to successfully simulate a wide range of different findings. These include: practice curves in the Stroop paradigm, contingency learning effects, learning acquisition curves, stimulus-response binding effects, mixing costs, and various findings from the attentional control domain. The results demonstrate several important points. First, the same retrieval mechanism parsimoniously explains stimulus-response binding, contingency learning, and practice effects. Second, as performance improves with practice, any effects will shrink with it. Third, a model of simple learning processes is sufficient to explain phenomena that are typically (but perhaps incorrectly) interpreted in terms of higher-order control processes. More generally, we argue that computational models with a fixed parameter set and wider breadth should be preferred over those that are restricted to a narrow set of phenomena.

Congruency sequence effects and previous response times: conflict adaptation or temporal learning?

In the present study, we followed up on a recent report of two experiments in which the congruency sequence effect-the reduction of the congruency effect after incongruent relative to congruent trials in Stroop-like tasks-was observed without feature repetition or contingency learning confounds. Specifically, we further scrutinized these data to determine the plausibility of a temporal learning account as an alternative to the popular conflict adaptation account. To this end, we employed a linear mixed effects model to investigate the role of previous response time in producing the congruency sequence effect, because previous response time is thought to influence temporal learning. Interestingly, slower previous response times were associated with a reduced current-trial congruency effect, but only when the previous trial was congruent. An adapted version of the parallel episodic processing (PEP) model was able to fit these data if it was additionally assumed that attention "wanders" during different parts of the experiment (e.g., due to fatigue or other factors). Consistent with this assumption, the magnitude of the congruency effect was correlated across small blocks of trials. These findings demonstrate that a temporal learning mechanism provides a plausible account of the congruency sequence effect.

Is conflict adaptation adaptive? An introduction to conflict monitoring theory and the ecological problems it faces.

Attending to a single stimulus (or dimension of a stimulus) requires filtering out distracting stimuli to avoid producing an incorrect response. The conflict monitoring (or conflict adaptation) account proposes that experience of conflict results in a shift of attention away from distracting stimuli and/or towards the target stimulus. The proportion congruent and congruency sequence effects are two findings often used to argue in favour of the conflict monitoring account. However, there are several potential limitations with conflict monitoring theory. This article explores some of the previously unarticulated (or rarely articulated) supplementary assumptions that must be made for the conflict monitoring account to be consistent with several important findings in the literature, some of which might undermine the initial intuitive appeal of the theory. Indeed, this opinion paper presents the view that conflict adaptation may not actually be particularly adaptive for performance. This article also discusses alternative interpretations of so-called "attentional control" phenomena. According to this view, participants may simply be learning regularities in the task structure that are unintentionally introduced when manipulating conflict (e.g., contingent regularities between distracting stimuli and responses). This sort of learning does benefit performance and is inherent for our functioning in the world, making this a more parsimonious view. Although simplicity is not everything, this article will present the case that the assumptions (often hidden or non-obvious) of conflict monitoring theory are non-trivial and, in many cases, imply relatively non-adaptive processes.

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.

Learning, awareness, and instruction: subjective contingency awareness does matter in the colour-word contingency learning paradigm.

In three experiments, each of a set colour-unrelated distracting words was presented most often in a particular target print colour (e.g., "month" most often in red). In Experiment 1, half of the participants were told the word-colour contingencies in advance (instructed) and half were not (control). The instructed group showed a larger learning effect. This instruction effect was fully explained by increases in subjective awareness with instruction. In Experiment 2, contingency instructions were again given, but no contingencies were actually present. Although many participants claimed to be aware of these (non-existent) contingencies, they did not produce an instructed contingency effect. In Experiment 3, half of the participants were given contingency instructions that did not correspond to the correct contingencies. Participants with these false instructions learned the actual contingencies worse than controls. Collectively, our results suggest that conscious contingency knowledge might play a moderating role in the strength of implicit learning.

Stimulus and response conflict from a second language: Stroop interference in weakly-bilingual and recently-trained languages.

The aim of the present manuscript was to investigate the source of congruency effects in weak bilinguals (Experiment 1) and in early language learning (Experiment 2). In both studies, participants performed a bilingual version of a colour-word Stroop task. The standard finding is slower and less accurate responding when the word and colour are incongruent (e.g., "red" in blue) relative to congruent (e.g., "red" in red). This congruency effect occurs for the distracting colour words from both the first and second language. Both stimulus conflict (i.e., conflict between the meaning of the word and ink colour) and response conflict (i.e., conflict between possible response options) contribute to first-language congruency effects. According to some models of early language learning, only one of these two types of conflict should emerge for non-fluent languages. To separate stimulus and response conflict, we used a 2-to-1 keypress assignment manipulation. Interestingly, in one study both stimulus and response conflict were evidenced for the weakly spoken second language (English in native French speakers). In a second study, participants performed a short Croatian colour word learning phase before the Stroop procedure. Stimulus conflict was observed in response times and response conflict in errors for this recently-trained language. These findings suggest that the relatively low-proficient second language words are potent enough to affect semantic identification and response selection.

Contingency learning and unlearning in the blink of an eye: a resource dependent process.

Recent studies show that when words are correlated with the colours they are printed in (e.g., MOVE is presented 75% of the time in blue), colour identification is faster when the word is presented in its correlated colour (MOVE in blue) than in an uncorrelated colour (MOVE in green). The present series of experiments explored the possible mechanisms involved in this colour-word contingency learning effect. Experiment 1 demonstrated that the effect is already present after 18 learning trials. During subsequent unlearning, the effect extinguished equally rapidly. Two reanalyses of data from Schmidt, Crump, Cheesman, and Besner (2007) ruled out an account of the effect in terms of stimulus repetitions. Experiment 2 demonstrated that participants who carry a memory load do not show a contingency effect, supporting the hypothesis that limited-capacity resources are required for learning. Experiment 3 demonstrated that memory resources are required for both storage and retrieval processes.

An Episodic Model of Task Switching Effects: Erasing the Homunculus from Memory.

The Parallel Episodic Processing (PEP) model is a neural network for simulating human performance in speeded response time tasks. It learns with an exemplar-based memory store and it is capable of modelling findings from various subdomains of cognition. In this paper, we show how the PEP model can be designed to follow instructions (e.g., task rules and goals). The extended PEP model is then used to simulate a number of key findings from the task switching domain. These include the switch cost, task-rule congruency effects, response repetition asymmetries, cue repetition benefits, and the full pattern of means from a recent feature integration decomposition of cued task switching (Schmidt & Liefooghe, 2016). We demonstrate that the PEP model fits the participant data well, that the model does not possess the flexibility to match any pattern of results, and that a number of competing task switching models fail to account for key observations that the PEP model produces naturally. Given the parsimony and unique explanatory power of the episodic account presented here, our results suggest that feature-integration biases have a far greater power in explaining task-switching performance than previously assumed.

Erasing the Homunculus as an Ongoing Mission: A Reply to the Commentaries.

In our recent article (Schmidt, Liefooghe, & De Houwer, 2020, this volume), we presented an adaptation of the Parallel Episodic Processing (PEP) model for simulating instruction following and task-switching behaviour. In this paper, we respond to five commentaries on our article: Monsell & McLaren (2020), Koch & Lavric (2020), Meiran (2020), Longman (2020), and Pfeuffer (2020). The commentaries discuss potential future modelling goals, deeper reflections on cognitive control, and some potential challenges for our theoretical perspective and associated model. We focus primarily on the latter. In particular, we clarify that we (a) acknowledge the role of cognitive control in task switching, and (b) are arguing that certain task-switching effects do not serve as a good measure of said cognitive control. We also discuss some ambiguities in terminological uses (e.g., the meaning of "task-set reconfiguration"), along with some future experimental and modelling research directions.

Contingency learning as binding? Testing an exemplar view of the colour-word contingency learning effect.

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 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 timescales. 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 reanalyses 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 towards 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 stimulus-response binding effects that are due to the last occurrence of a stimulus rendered contingency learning effects non-significant. Implications for memory models are discussed.

Stroop-like effects of derived stimulus-stimulus relations.

Automaticity can be established by consistently reinforcing contingencies during practice. During reinforcement learning, however, new relations can also be derived, which were never directly reinforced. For instance, reinforcing the overlapping contingencies A → B and A → C, can lead to a new relation B-C, which was never directly reinforced. Across 5 experiments we investigated if such derived relations can also induce automatic effects. We first trained participants to derive a relation between a nonsense word and a color word, and then used the nonsense words as distractors in a Stroop task. Results indicate that derived color-word associates induce Stroop effects. This effect, however, is present only when sufficient attention is allocated to the distractor words during the Stroop task, and is driven by a response conflict. We conclude that, under the present training conditions, derived color-word associates became related to the corresponding color word at the lexical level, but did not gain direct access to the corresponding semantic color representation. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Modulation of vascular O2 responses by cytochrome 450-4A omega-hydroxylase metabolites in Dahl salt-sensitive rats.

OBJECTIVE: This study evaluated the role of the 20-HETE/cytochrome P450-4A omega-hydroxylase (CYP450-4A) system in microvascular regulation in the skeletal muscle circulation following short-term (three-day) exposure to a high-salt (HS) diet in Dahl salt-sensitive (SS) rats. METHODS: The effects of inhibiting CYP450-4A on resting diameter, O(2)-induced constriction, and vasodilator responses to acetylcholine (ACh) and the nitric oxide (NO) donor, sodium nitroprusside (SNP), were evaluated in cremasteric arterioles of SS rats fed a low- (LS; 0.4% NaCl) or high-salt (HS; 4% NaCl) diet for three days. RESULTS: The HS diet upregulated CYP450-4A mRNA expression and led to an enhanced constriction of arterioles in response to elevated PO(2) in SS rats, which could be blocked by inhibiting CYP450-4A enzymes with dibromododecenyl methylsulfimide (DDMS). DDMS also inhibited resting tone significantly in SS rats fed the HS, but not the LS, diet, despite similar resting diameters and active tone in the two groups. Arteriolar dilations in response to ACh and SNP were similar in SS rats fed the LS vs. the HS diet and were unaffected by DDMS. CONCLUSIONS: These findings suggest that CYP450-4A enzymes contribute to resting tone and to an enhanced response to elevated PO(2) in arterioles of Dahl-SS rats fed the HS diet.

Time-course and mechanisms of restored vascular relaxation by reduced salt intake and angiotensin II infusion in rats fed a high-salt diet.

OBJECTIVE: This study determined the mechanisms and time-course of recovery of vascular relaxation in middle cerebral arteries (MCAs) of salt-fed Sprague-Dawley rats returned to a low-salt (LS) diet (0.4% NaCl) or infused with low-dose angiotensin II (ANG II). METHODS: Rats were fed a high-salt (HS) diet (4% NaCl) for 3 days or 4 weeks before returning to an LS diet for various periods. Other rats fed a HS diet (HS+ANG II) received a chronic (3 days) intravenous (i.v.) infusion of a low dose of ANG II (5 ng kg(-1) min(-1)) to prevent salt-induced ANG II suppression. RESULTS: The HS diet eliminated the increase in cerebral blood flow in response to acetylcholine (ACh) infusion and the relaxation of MCA in response to ACh, iloprost, cholera toxin, and reduced PO2. Recovery of vascular relaxation was slow, requiring at least 2 weeks of the LS diet, regardless of the duration of exposure to a HS diet. Hypoxic dilation was mediated by cyclo-oxygenase metabolites and ACh-induced dilation was mediated via nitric oxide in LS rats and in HS rats returned to the LS diet or receiving ANG II infusion. CONCLUSIONS: Returning to a LS diet for 2 weeks or chronic 3-day ANG II infusion restores the mechanisms that normally mediate cerebral vascular relaxation.

Evidence against conflict monitoring and adaptation: An updated review.

One of the most influential ideas in recent decades in the cognitive psychology literature is conflict monitoring theory. According to this account, each time we experience a conflict (e.g., between a colour word and print colour in the Stroop task), attentional control is upregulated to minimize distraction on subsequent trials. Though influential, evidence purported to support this theoretical model (primarily, proportion congruent and congruency sequence effects) has been frequently criticized. Furious debate has centered on whether or not conflict monitoring does or does not occur and, if so, under which conditions. The present article presents an updated review of this debate. In particular, the article considers new research that either (a) seems particularly damaging for the conflict monitoring view or (b) seems to provide support for the theory. The author argues that new findings of the latter sort are still not compelling, several of which have already-demonstrated confounds and others which are plausibly confounded. Further progress has, to a greater extent than not, provided even stronger support for the position that conflict monitoring is merely an illusion. Instead, the net results can be more coherently understood in terms of (relatively) simpler learning/memory biases unrelated to conflict or attention that confound the key paradigms.

Context-specific proportion congruent effects: Compound-cue contingency learning in disguise.

Conflict between task-relevant and task-irrelevant stimulus information leads to impairment in response speed and accuracy. For instance, in the colour-word Stroop paradigm, participants respond slower and less accurately to the print colour of incongruent colour words (e.g., "red" printed in green) than to congruent colour words (e.g., "green" in green). Importantly, this congruency effect is diminished when the trials in an experiment are mostly incongruent, relative to mostly congruent, termed a proportion congruent effect. When distracting stimuli are mostly congruent in one context (e.g., location or font) but mostly incongruent in another context (e.g., another location or font), the congruency effect is still diminished in the mostly incongruent context, termed a context-specific proportion congruent (CSPC) effect. Both the standard proportion congruent and CSPC effects are typically interpreted in terms of conflict-driven attentional control, frequently termed conflict adaptation or conflict monitoring. However, in two experiments, we investigated contingency learning confounds in context-specific proportion congruent effects. In particular, two variants of a dissociation procedure are presented with the font variant of the CSPC procedure. In both, robust contingency learning effects were observed. No evidence for context-specific control was observed. In fact, results trended in the wrong direction. In all, the results suggest that CSPC effects may not be a useful way of studying attentional control.