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.     

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).     

Hating the cute kitten or loving the aggressive pit-bull: EC effects depend on CS–US relations

Evaluative conditioning (EC) refers to valence changes of initially neutral stimuli (CSs) through repeated pairings with positive or negative stimuli (USs). The current study is about the moderating role of qualifiers that specify the CS–US relation during these pairings. We show successful EC with pictures of men (CSs) and of liked/disliked animals or landscapes (USs). More importantly, the same pairings resulted in standard and reversed EC effects depending on semantic qualifier of the CS–US relation. CSs loving positive (negative) USs became more positive (negative), while CSs loathing positive (negative) USs became more negative (positive). These data favour a propositional EC account (De Houwer, 2009) over a purely associative account, as they show that it is not only relevant that CS and US are related, but how they are related.     

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.     

Using the Implicit Association Test does not rule out an impact of conscious propositional knowledge on evaluative conditioning

Implicit measures such as the Implicit Association Test (IAT) have recently become popular as tools in research on evaluative conditioning. The reason is that these measures are thought to be impervious to changes in valence that are due to conscious propositional knowledge about the relation between the conditioned stimulus (CS) and the unconditioned stimulus (US). I present data that raise doubts about the validity of this assumption. In two experiments, attitudes towards CSs as measured by the IAT were in line with instructed CS-US contingencies even though the CSs and USs were never actually paired. The results therefore suggest that IAT effects can be biassed by conscious propositional knowledge.     

One but not the same: Evaluative conditioning with mixed-valence USs

In evaluative conditioning (EC), the pairing of a positively or negatively valenced stimulus (US) with another neutral stimulus (CS) leads to a corresponding change in liking of the CS. EC research so far has concentrated on using unambiguously positive or negative USs. However, attitude objects often possess multiple features that can be positive and negative at the same time. The present research addresses the question of how EC is affected by using such mixed-valence stimuli as USs. In two studies, USs of mixed valence (i.e., positive behavior and membership in a negative group or vice versa) were paired with affectively neutral CSs. Interestingly, results showed that the mixed-valence USs were evaluated according to the valence of the behavioral information. In contrast, the evaluation of associated CSs was more strongly influenced by the valence of the group information that was presented about the USs. Possible explanations as well as implications for EC research are discussed.     

Is the devil in the detail? Evidence for S-S learning after unconditional stimulus revaluation in human evaluative conditioning under a broader set of experimental conditions

Whether valence change during evaluative conditioning is mediated by a link between the conditional stimulus (CS) and the unconditional stimulus (US; S-S learning) or between the CS and the unconditional response (S-R learning) is a matter of continued debate. Changing the valence of the US after conditioning, known as US revaluation, can be used to dissociate these accounts. Changes in CS valence after US revaluation provide evidence for S-S learning but if CS valence does not change, evidence for S-R learning is found. Support for S-S learning has been provided by most past revaluation studies, but typically the CS and US have been from the same stimulus category, the task instructions have suggested that judgements of the CS should be based on the US, and USs have been mildly valenced stimuli. These factors may bias the results in favour of S-S learning. We examined whether S-R learning would be evident when CSs and USs were taken from different categories, the task instructions were removed, and more salient USs were used. US revaluation was found to influence explicit US evaluations and explicit and implicit CS evaluations, supporting an S-S learning account and suggesting that past results are stable across procedural changes.     

Analyzing the random control procedure: Effects of paired and unpaired CSs and USs on autoshaping the chick's key peck with heat reinforcement

A series of five experiments using a total of 264 subjects investigated the effects of paired and unpaired key light (CS) and heat (US) stimuli on autoshaping the chick's key peck. Experiment 1 established that paired presentations of CS and US promoted a more rapid rise in key pecking than did randomly presented CSs and USs and that the specific sequence of stimuli under the random control procedure affected key pecking performance. Experiment 2 used a trace conditioning procedure to determine the role of the CS-US interval on autoshaping and to define empirically unpaired CSs and USs. Key pecking declined as the trace delay interval was increased from 0 to 25 sec; at 25 sec, no conditioning of key pecking occurred. Experiments 3–5 assessed the effects on autoshaped key pecking of (a) number of daily CS-US pairings, (b) added unpaired CS presentations, and (c) added unpaired US presentations, since paired and random control schedules differed in all of these respects. Reduction in the number of CS-US pairings slowed the acquisition of key pecking as did the concurrent addition of nonreinforced CSs and unsignaled USs. These results support theories of association formation that stress the effects of both paired and unpaired CSs and USs.     

Evaluative conditioning effects are modulated by the nature of contextual pairings

Across two studies participants completed a learning phase comprised of two types of trials: context pairing trials in which two (valenced or non-valenced) words were identical or opposite to one another and evaluative conditioning (EC) trials in which a CS was paired with a US. Based on the idea that EC occurs because CS-US pairings function as a symbolic cue about the relation between the CS and the US, we hypothesised that the nature of context pairings (identical or opposite) might moderate EC effects. Results indicate that identity-based context pairs led to typical assimilative explicit and implicit effects whereas opposition-based pairs led to attenuated effects. Implications and different accounts of our findings are discussed.     

评价性条件反射效应：无条件刺激的呈现时长、效价强度与关联意识的作用

以真实商标图案为条件刺激, 情绪图片为无条件刺激, 探索无条件刺激呈现时长、效价强度与关联意识对评价性条件反射效应的影响。实验通过结合四图再认测验与基于项目分析, 对关联意识的作用进行了详细探讨。结果表明, 评价性条件反射效应只发生在无条件刺激长呈现水平与无条件刺激强效价水平; 评价性条件反射效应的产生需要基于被试的关联意识。关联意识在呈现时长(效价强度)与评价性条件反射效应间的中介作用不显著。结果不支持评价性条件反射的内隐错误归因机制及联想-命题评价模型的相关论断, 部分支持命题性解释模型。     

Preservation of Pavlovian Associations through Extinction

Rats received Pavlovian pairings of conditioned stimuli (CSs) with discriminably different unconditioned stimuli (USs). The resulting CS-US associations, indexed by magazine entry, were subjected to extinction and to interference by pairing the CSs with other USs. Subsequent differential devaluation of the USs by pairing with LiCl revealed the continued presence of the CS-US associations despite these treatments.     

Subjective,physiological, and behavioural responses towards evaluatively conditioned stimuli

Evaluative Conditioning (EC) is commonly defined as the change in liking of a stimulus (conditioned stimulus, CS) due to its pairings with an affective unconditioned stimulus (US). In Experiment 1, we investigated effects of repeated stimulus pairings on affective responses, i.e. valence and arousal ratings, pupil size, and duration estimation. After repeatedly pairing the CSs with affective USs, a consistent pattern of affective responses emerged: The CS_negative was rated as being more negative and more arousing, resulted in larger pupils, and was temporally overestimated compared to the CS_neutral. In Experiment 2, the influence of a mere instruction about the contingency between a CS and US on affective responses was examined. After mere instruction about upcoming pairings between the CS and US, subjective ratings also changed, but there was neither evidence for differential pupillary responses nor for differential temporal processing. The results indicate that EC via pairings or instructions can change the affective responses towards formerly neutral stimuli and introduce pupil size as a physiological measure in EC research. However, Experiment 2 suggests that there might be moderating factors based on the type of EC procedure involved.     

Extinction of likes and dislikes: effects of feature-specific attention allocation

The evaluative conditioning (EC) effect refers to the change in the liking of a neutral stimulus (conditioned stimulus, CS) due to its pairing with another stimulus (unconditioned stimulus, US). We examined whether the extinction rate of the EC effect is moderated by feature-specific attention allocation. In two experiments, CSs were abstract Gabor patches varying along two orthogonal, perceptual dimensions (i.e. spatial frequency and orientation). During the acquisition phase, one of these dimensions was predictive of the valence of the USs. During the extinction phase, CSs were presented alone and participants were asked to categorise the CSs either according to their valence, the perceptual dimension that was task-relevant during the acquisition phase, or a perceptual dimension that was task-irrelevant during the acquisition phase. As predicted, explicit valence measures revealed a linear increase in the extinction rate of the EC effect as participants were encouraged to assign attention to non-evaluative stimulus information during the extinction phase. In Experiment 1, Affect Misattribution Paradigm (AMP) data mimicked this pattern of results, although the effect just missed conventional levels of significance. In Experiment 2, the AMP data revealed an increase of the EC effect if attention was focused on evaluative stimulus information. Potential mechanisms to explain these findings are discussed.     

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.     

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.     

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.     

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.     

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.     

Implicit attitude formation through classical conditioning

We sought to demonstrate that attitudes can develop through implicit covariation detection in a new classical conditioning paradigm. In two experiments purportedly about surveillance and vigilance, participants viewed several hundred randomly presented words and images interspersed with critical pairings of valenced unconditioned stimuli (USs) with novel conditioned stimuli (CSs). Attitudes toward the novel objects were influenced by the paired USs: In a surprise evaluation task, the CS paired with positive items was evaluated more positively than the CS paired with negative items. This attitudinal conditioning effect was found using both an explicit measure (Experiments 1 and 2) and an implicit measure (Experiment 2). In a covariation estimation task involving the stimuli presented in the conditioning procedure, participants displayed no explicit memory for the pairings.     

Prevention of the degraded-contingency effect by signalling training trials

Presentation of unsignalled unconditioned stimuli (USs) interspersed among Pavlovian excitatory conditioning trials weakens conditioned responding to a target conditioned stimulus (CS; Rescorla, 1968). However, signalling these intertrial USs with another cue (a cover stimulus) has been shown to alleviate this degraded-contingency effect (e.g. Durlach, 1982, 1983). In contrast to signalling the inter-trial USs, the present experiments examined the effect on the degraded-contingency effect of signalling the target CS-US pairings. Experiment 1, using parameters selected to avoid overshadowing, found that consistently presenting a cover stimulus immediately prior to the target CS-US pairings during degraded-contingency training alleviated the degraded-contingency effect. Experiment 2 examined the underlying mechanism responsible for this cover-stimulus effect through posttraining associative inflation of the cover stimulus or the context, and found that inflation of the cover stimulus attenuated responding to the target CS (i.e. empirical retrospective revaluation). The results are discussed in terms of various acquisition- and expression-focused models of acquired responding.