On the intentional control of conditioned evaluative responses

The evaluative conditioning (EC) effect is defined as a change in the evaluation of a conditioned stimulus (CS) due to its pairing with a valenced unconditioned stimulus (US). The current research investigated the controllability of EC effects by asking participants to either promote or prevent the influence of CS–US pairings before they provided evaluative ratings of the CS. Experiment 1 showed that instructions to maximize or minimize the influence of CS–US pairings moderated EC effects in line with task instructions. However, this moderation was observed only when participants were able to recall the valence of the US that had been paired with a given CS. When participants failed to remember the valence of the US, significant EC effects emerged regardless of control instructions. Experiment 2 tested whether the influence of CS–US pairings on CS evaluations can be intentionally reversed. The results showed that reversal instructions led to a reverse EC effect when participants were able to recall the valence of the US that had been paired with a given CS, but not when they were unable to recall the valence of the US. Taken together, these results suggest that US valence memory is a necessary precondition for controlling the expression of a conditioned evaluative response, but it is not a necessary precondition for the emergence of EC effects per se.     

Evaluative conditioning without directly experienced pairings of the conditioned and the unconditioned stimuli

Evaluative conditioning (EC) is the valence change of a stimulus (conditioned stimulus, CS) that is due to the previous pairing with another stimulus (unconditioned stimulus, US). We investigated whether EC can occur also when the CS–US pairings are not experienced directly by the participant but are implied by other events that the participant encounters. In two experiments, positive USs were presented in some trials and negative USs in other trials. Afterwards, participants were given information from which it was possible to conclude that CSs were covertly present during these trials. Finally, the valence of these CSs was registered using both implicit (Implicit Association Test, affective priming) and explicit measures (valence ratings). In line with the assumption that EC effects can be based on CS–US pairings that are not directly experienced, the valence of the CSs changed in the direction of the US with which they were covertly paired. This effect was observed both on explicit and on implicit measures. We argue that several aspects of our results are in line with propositional models of EC and fit less well with association formation models.     

Evaluative conditioning can be modulated by memory of the CS–US pairings at the time of testing

Evaluative conditioning (EC) is the valence change of a (typically neutral) stimulus (CS) that is due to the previous pairing with another (typically valent) stimulus (US). It has been repeatedly shown that EC effects are stronger or existent only if participants know which US was paired with which CS. Knowledge of the CS–US pairings is usually measured temporally close to both the conditioning phase and the CS valence measurement phase. Hence, the relation between EC and knowledge about the pairings could indicate either that participants need to become aware of the pairings at some point or that they need to remember them during the CS valence test. We isolated the impact of memory during the CS valence test in a study that encompassed two sessions. During the first session, participants were presented with CS–US pairings. The valence of the CSs was measured in a second session several days later using both a rating scale and an affective priming procedure. Memory for the pairings was measured both during the first and the second session. Using item-based multilevel analysis, we found that EC in the second session was related to memory for the pairings during the second session, but not to the memory for the pairings measured immediately after the learning phase. For the pairs that were remembered during the first session, but not during the second session, no EC effect was found. These results suggest that memory for CS–US pairings during valence measurement can be relevant for EC effects to occur.     

The effects of unconditional stimulus valence and conditioning paradigm on verbal,skeleto-motor,and autonomic indices of human Pavlovian conditioning

The effects of unconditional stimulus (US) valence (aversive electro-tactile stimulus vs. non-aversive imperative stimulus of a RT task) and conditioning paradigm (delay vs. trace) on affective learning as indexed by verbal ratings of conditional stimulus (CS) pleasantness and blink startle modulation and on relational learning as indexed by electrodermal responses were investigated. Affective learning was not affected by the conditioning paradigm; however, electrodermal responses and blink latency shortening indicated delayed learning in the trace procedure. Changes in rated CS pleasantness were found with the aversive US, but not with the non-aversive US. Differential conditioning as indexed by electrodermal responses and startle modulation was found regardless of US valence. The finding of significant differential blink modulation and electrodermal responding in the absence of a change in rated CS pleasantness as a result of conditioning with a non-aversive US was replicated in a second experiment. These results seem to indicate that startle modulation during conditioning is mediated by the arousal level of the anticipated US, rather than by the valence of the CS.     

Evaluative conditioning without directly experienced pairings of the conditioned and the unconditioned stimuli

Evaluative conditioning (EC) is the valence change of a stimulus (conditioned stimulus, CS) that is due to the previous pairing with another stimulus (unconditioned stimulus, US). We investigated whether EC can occur also when the CS-US pairings are not experienced directly by the participant but are implied by other events that the participant encounters. In two experiments, positive USs were presented in some trials and negative USs in other trials. Afterwards, participants were given information from which it was possible to conclude that CSs were covertly present during these trials. Finally, the valence of these CSs was registered using both implicit (Implicit Association Test, affective priming) and explicit measures (valence ratings). In line with the assumption that EC effects can be based on CS-US pairings that are not directly experienced, the valence of the CSs changed in the direction of the US with which they were covertly paired. This effect was observed both on explicit and on implicit measures. We argue that several aspects of our results are in line with propositional models of EC and fit less well with association formation models.     

Reactance in affective-evaluative learning: Outside of conscious control?

Recent studies have shown that the basic evaluative conditioning (EC) effect (originally neutral stimuli acquiring an affective value congruent with the valence of the affective stimulus they were paired with) seems to be limited to participants who are unaware of the stimulus pairings. If participants are aware of the pairings, reactance effects occur (i.e., changes in the opposite direction of the valence of the affective stimulus). To examine whether these reactance effects are due to processes of conscious countercontrol or whether the ratings reflect intrinsic feelings towards the stimuli, a new procedure was developed that included a bogus-pipeline condition. In this procedure, which was adapted from attitude research, participants were connected to bogus lie detector equipment leading them to believe that their "true" affective-evaluative responses were being observed. In Experiment 1, reactance effects occurred also in this procedure, suggesting that the effect is spontaneous and not due to processes of conscious countercontrol. In Experiment 2, these effects were replicated using a between-subjects design in addition to the standard within-subjects control condition.     

Verbal instructions targeting valence alter negative conditional stimulus evaluations (but do not affect reinstatement rates)

Negative conditional stimulus (CS) valence acquired during fear conditioning may enhance fear relapse and is difficult to remove as it extinguishes slowly and does not respond to the instruction that unconditional stimulus (US) presentations will cease. We examined whether instructions targeting CS valence would be more effective. In Experiment 1, an image of one person (CS+) was paired with an aversive US, while another (CS?) was presented alone. After acquisition, participants were given positive information about the CS+ poser and negative information about the CS? poser. Instructions reversed the pattern of differential CS valence present during acquisition and eliminated differential electrodermal responding. In Experiment 2, we compared positive and negative CS revaluation by providing positive/negative information about the CS+ and neutral information about CS?. After positive revaluation, differential valence was removed and differential electrodermal responding remained intact. After negative revaluation, differential valence was strengthened and differential electrodermal responding was eliminated. Unexpectedly, the instructions did not affect the reinstatement of differential electrodermal responding.     

Recent books

Recent studies have shown that the basic evaluative conditioning (EC) effect (originally neutral stimuli acquiring an affective value congruent with the valence of the affective stimulus they were paired with) seems to be limited to participants who are unaware of the stimulus pairings. If participants are aware of the pairings, reactance effects occur (i.e., changes in the opposite direction of the valence of the affective stimulus). To examine whether these reactance effects are due to processes of conscious countercontrol or whether the ratings reflect intrinsic feelings towards the stimuli, a new procedure was developed that included a bogus‐pipeline condition. In this procedure, which was adapted from attitude research, participants were connected to bogus lie detector equipment leading them to believe that their “true” affective‐evaluative responses were being observed. In Experiment 1, reactance effects occurred also in this procedure, suggesting that the effect is spontaneous and not due to processes of conscious countercontrol. In Experiment 2, these effects were replicated using a between‐subjects design in addition to the standard within‐subjects control condition.     

Differential effects of two ways of devaluing the unconditioned stimulus after Pavlovian appetitive conditioning

Three experiments with rat subjects investigated the effects of two methods of devaluing a food unconditioned stimulus (US) after pairings of an auditory conditioned stimulus (CS) with that US. Experiment 1 found no effect of postconditioning pairings of the food US with lithium chloride (LiCl) on general activity to a tone CS, even though those pairings substantially reduced food consumption. Experiments 2 and 3 compared the effects on conditioned responding of postconditioning pairings of food with LiCl and with high-speed rotation. In these experiments the general activity measure was supplemented by a detailed visual analysis of the rats' behavior. Experiment 2 found that food-rotation pairings had larger effects than food-LiCl pairings on general activity responding and on two detailed behavioral measures but that food-LiCl pairings had larger effects on food consumption and on one behavioral measure. Experiment 3 replicated the findings of Experiment 2 and found that the ability of the CS to serve as a reinforcer for second-order conditioning after US devaluation was reduced more by food-LiCl pairings.     

Fearing shades of grey: individual differences in fear responding towards generalisation stimuli

Individual differences in fear generalisation have been proposed to play a role in the aetiology and/or maintenance of anxiety disorders, but few data are available to directly support that claim. The research that is available has focused mostly on generalisation of peripheral and central physiological fear responses. Far less is known about the generalisation of avoidance, the behavioural component of fear. In two experiments, we evaluated how neuroticism, a known vulnerability factor for anxiety, modulates an array of fear responses, including avoidance tendencies, towards generalisation stimuli (GS). Participants underwent differential fear conditioning, in which one conditioned stimulus (CS+) was repeatedly paired with an aversive outcome (shock; unconditioned stimulus, US), whereas another was not (CS?). Fear generalisation was observed across measures in Experiment 1 (US expectancy and evaluative ratings) and Experiment 2 (US expectancy, evaluative ratings, skin conductance, startle responses, safety behaviours), with overall highest responding to the CS+, lowest to the CS? and intermediate responding to the GSs. Neuroticism had very little impact on fear generalisation (but did affect GS recognition rates in Experiment 1), in line with the idea that fear generalisation is largely an adaptive process.     

Is evaluative conditioning really resistant to extinction? Evidence for changes in evaluative judgements without changes in evaluative representations

Evaluative conditioning (EC) is defined as the change in the evaluation of a conditioned stimulus (CS) due to its pairing with a positive or negative unconditioned stimulus (US). Although several individual studies suggest that EC is unaffected by unreinforced presentations of the CS without the US, a recent meta-analysis indicates that EC effects are less pronounced for post-extinction measurements than post-acquisition measurements. The disparity in research findings suggests that extinction of EC may depend on yet unidentified conditions. In an attempt to uncover these conditions, three experiments (N = 784) investigated the influence of unreinforced post-acquisition CS presentations on EC effects resulting from simultaneous versus sequential pairings and pairings with single versus multiple USs. For all four types of CS–US pairings, EC effects on self-reported evaluations were reduced by unreinforced CS presentations, but only when the CSs had been rated after the initial presentation of CS–US pairings. EC effects on an evaluative priming measure remained unaffected by unreinforced CS presentations regardless of whether the CSs had been rated after acquisition. The results suggest that reduced EC effects resulting from unreinforced CS presentations are due to judgement-related processes during the verbal expression of CS evaluations rather than genuine changes in the underlying evaluative representations.     

Aware and (dis)liking: item-based analyses reveal that valence acquisition via evaluative conditioning emerges only when there is contingency awareness

Evaluative conditioning (EC) refers to changes in the liking of an affectively neutral stimulus (the conditioned stimulus, or CS) following the pairing of that stimulus with another stimulus of affective value (the unconditioned stimulus, or US). In 3 experiments, the authors assessed contingency awareness, that is, awareness of the CS-US associations, by relying on participants' responses to individual items rather than using a global method of assessment. They found that EC emerged on contingency aware CSs only. Of note, whether the CSs were evaluated explicitly (Experiments 1 and 2) or implicitly (Experiment 3) did not make a difference. This pattern supports the idea that awareness of the CS-US associations may be required for valence acquisition via EC.     

The influence of extinction and counterconditioning instructions on evaluative conditioning effects

In three experiments, we tested the influence of instructions about an allegedly upcoming extinction or counterconditioning phase on evaluative conditioning (EC) effects. After an acquisition phase in which neutral stimuli were related to positive or negative stimuli via instructions (Experiments 1 and 2a) or actual pairings (Experiment 2b), three different groups of participants were either informed that in the next phase the neutral stimuli would be presented without positive or negative stimuli (extinction instruction), that the neutral stimuli in the next phase would be paired with stimuli of the opposite valence than before (counterconditioning instruction), or received no further instructions. Afterwards, liking of the originally neutral stimuli was measured either with an evaluative rating (Experiment 1) or with an Implicit Association Test (IAT; Experiments 2a and 2b). EC was reduced in the counterconditioning condition of Experiment 1 and in the joint analysis of Experiments 2a and 2b. The extinction instruction led to a reduction of EC only in Experiment 1. Finally, whether the acquisition phase consisted of instructions about CS–US pairings (Experiment 2a) or the actual experience of CS–US pairings (Experiment 2b) did not significantly impact the observed changes in liking. Overall, our results suggest that similar mechanisms might mediate instruction- and experienced-based EC. Our results are in line with propositional models of EC but can be explained also by association formation models and dual process models of EC, provided that certain auxiliary assumptions are made.     

I like it because I said that I like it: evaluative conditioning effects can be based on stimulus-response learning

Evaluative conditioning (EC) effects are often assumed to be based on a learned mental link between the CS (conditioned stimulus) and the US (unconditioned stimulus). We demonstrate that this link is not the only one that can underlie EC effects, but that if evaluative responses are actually given during the learning phase also a direct link between the CS and an evaluative response-a CS-ER link-can be learned and lead to EC effects. In Experiment 1, CSs were paired with USs and participants were asked to evaluate the pairs during the conditioning phase. Resulting EC effects were unaffected by a later revaluation of the USs, suggesting that these EC effects can be attributed to CS-ER learning rather than to CS-US learning. Experiment 2 replicated Experiment 1 with the difference that no evaluative responses were given during the learning phase. EC effects in this study were influenced by US revaluation, suggesting that these EC effects are mainly based on CS-US learning. In Experiment 3, it was shown that EC effects can be found even if the USs are entirely removed from the procedure and the CSs are only paired with enforced evaluative responses. Together the experiments show that the valence of a stimulus can change because of a contingency with an evaluative response. (PsycINFO Database Record (c) 2011 APA, all rights reserved).     

What you see is what will change: Evaluative conditioning effects depend on a focus on valence

This study investigated whether evaluative conditioning (EC) effects depend on an evaluative focus during the learning phase. An EC effect is a valence change of an originally neutral stimulus (conditioned stimulus or CS) that is due to the former pairing with a positive or negative stimulus (unconditioned stimulus or US). In three experiments, the task focus during the conditioning phase was manipulated. Participants judged CS–US pairings either with respect to their valence or with respect to another stimulus dimension. EC effects on explicit and implicit measures were found when valence was task relevant but not when the non-valent stimulus dimension was task relevant. Two accounts for the valence focus effect are proposed: (1) An additional direct learning of the relation of CS and evaluative responses in the valence focus condition, or (2) a stronger activation of US valence in the valence focus condition compared to the non-valent focus condition.     

Observational evaluative conditioning of an embedded stimulus element

Evaluative conditioning refers to the observation that the mere paired presentation of a neutral stimulus (CS) with a liked or disliked stimulus (US) may result in the neutral stimulus itself acquiring positive or negative valence. In most studies, the CS is an autonomous, invariant stimulus, and the subject directly experiences both CS and US. In this experiment, we investigated whether evaluative conditioning can be extended to a situation wherein the CS is no more than an invariant element of a complex, variable stimulus configuration, and wherein the subject experiences the CS–US co-occurrences indirectly, i.e. by observing a socius who is exposed to the CS–US pairings and facially expresses either liking or disliking the US. During acquisition, subjects watched video-taped sequences of an actor drinking a glass containing a liquid and facially expressing either liking or disliking the drink. The stimulus element which was systematically paired with the actor's facial expression of liking or disliking, was whether the glass contained a ‘foot’ or no ‘foot’ (CS), while other characteristics of the scenes were systematically varied and paired equally often with an expression of like and dislike. Next, valence ratings were obtained for pictures in which the CS element (foot/no foot) was embedded. A clear observational evaluative learning effect could be demonstrated when the feature CS was embedded in objects identical to those presented during learning, but not when it was embedded in new objects. These data demonstrate the possibility of vicarious evaluative conditioning of an embedded stimulus element, but probably at a lower level of abstraction than intended.     

When congruence breeds preference: the influence of selective attention processes on evaluative conditioning

We investigated in two experiments whether selective attention processes modulate evaluative conditioning (EC). Based on the fact that the typical stimuli in an EC paradigm involve an affect-laden unconditioned stimulus (US) and a neutral conditioned stimulus (CS), we started from the assumption that learning might depend in part upon selective attention to the US. Attention to the US was manipulated by including a variant of the Eriksen flanker task in the EC paradigm. Similarly to the original Flanker paradigm, we implemented a target-distracter logic by introducing the CS as the task-relevant stimulus (i.e. the target) to which the participants had to respond and the US as a task-irrelevant distracter. Experiment 1 showed that CS–US congruence modulated EC if the CS had to be selected against the US. Specifically, EC was more pronounced for congruent CS–US pairs as compared to incongruent CS–US pairs. Experiment 2 disentangled CS–US congruence and CS–US compatibility and suggested that it is indeed CS–US stimulus congruence rather than CS–US response compatibility that modulates EC.     

Fear conditioning in posttraumatic stress disorder: evidence for delayed extinction of autonomic, experiential, and behavioural responses

Aversive conditioning has been proposed as an important factor involved in the etiology of posttraumatic stress disorder (PTSD). However, it is not yet fully understood exactly which learning mechanisms are characteristic for PTSD. PTSD patients (n=36), and healthy individuals with and without trauma exposure (TE group, n=21; nTE group, n=34), underwent a differential fear conditioning experiment consisting of habituation, acquisition, and extinction phases. An electrical stimulus served as the unconditioned stimulus (US), and two neutral pictures as conditioned stimuli (CS+, paired; CS-, unpaired). Conditioned responses were quantified by skin conductance responses (SCRs), subjective ratings of CS valence and US-expectancy, and a behavioural test. In contrast to the nTE group, PTSD patients showed delayed extinction of SCRs to the CS+. Online ratings of valence and US-expectancy as well as the behavioural test confirmed this pattern. These findings point to a deficit in extinction learning and highlight the role of affective valence appraisals and cognitive biases in PTSD. In addition, there was some evidence that a subgroup of PTSD patients had difficulties in learning the CS-US contingency, thereby providing preliminary evidence of reduced discrimination learning.     

What do memory data tell us about the role of contingency awareness in evaluative conditioning?

Evaluative conditioning (EC) refers to the effect that pairings of a conditioned stimulus (CS) with a valenced unconditioned stimulus (US) lead to changes in the evaluation of the CS. There have been recurring debates about whether EC requires awareness of the contingency between CSs and USs during learning. We argue that the memory performance data obtained in the standard paradigm remain ambiguous about the role of contingency awareness during the encoding of CS–US pairings. First, memory performance data are unable to distinguish between encoding-related versus retrieval-related effects. Second, the relation between memory performance and evaluation is correlational, which limits conclusions about causal relations between memory performance and EC effects. These ambiguities imply that any possible data pattern can be interpreted in at least two different ways. It is concluded that a resolution of the current debate requires alternative approaches in which contingency awareness is experimentally manipulated during the encoding of CS–US pairings.     

What you see is what will change: evaluative conditioning effects depend on a focus on valence

This study investigated whether evaluative conditioning (EC) effects depend on an evaluative focus during the learning phase. An EC effect is a valence change of an originally neutral stimulus (conditioned stimulus or CS) that is due to the former pairing with a positive or negative stimulus (unconditioned stimulus or US). In three experiments, the task focus during the conditioning phase was manipulated. Participants judged CS-US pairings either with respect to their valence or with respect to another stimulus dimension. EC effects on explicit and implicit measures were found when valence was task relevant but not when the non-valent stimulus dimension was task relevant. Two accounts for the valence focus effect are proposed: (1) An additional direct learning of the relation of CS and evaluative responses in the valence focus condition, or (2) a stronger activation of US valence in the valence focus condition compared to the non-valent focus condition.