Evaluative Conditioning: Past, Present, and Future.

Evaluative conditioning (EC) research investigates changes in the evaluation of a stimulus after co-occurrence with an affective stimulus. To explain the motivation behind this research, this review begins with an overview of the history of EC research, followed by a summary of the state of the art with respect to three key questions. First, how should EC procedures be used to influence evaluation? We provide a guide based on evidence concerning the functional properties of EC effects. Second, how does the EC effect occur? We discuss the possible mediating cognitive processes and their automaticity. Third, are EC effects ubiquitous outside the lab? We discuss the evidence for the external validity of EC research. We conclude that the most important open questions pertain to the relevance of EC to everyday life and to the level of control that characterizes the processes that mediate the EC effect after people notice the stimulus co-occurrence.

Four studies yield limited evidence for prepared (disgust) learning via evaluative conditioning.

Prepared learning accounts suggest that specialized learning mechanisms increase the retention of associations linked to ancestrally-prevalent threats. Few studies have investigated specialized aversion learning for pathogen threats. In four pre-registered studies (N's = 515, 495, 164, 175), we employed an evaluative conditioning procedure to test whether foods (versus non-foods) are more readily associated with negative content associated with pathogens than negative content not associated with pathogens. Participants saw negatively valenced (either pathogen-relevant or -irrelevant), neutral or positively-valenced stimuli paired with meats and plants (in Studies 1 and 2) and with meats and abstract shapes (in Studies 3 and 4). They then evaluated each stimulus explicitly via self-reports (Studies 1-4) and implicitly via an Affect Misattribution Procedure (Studies 3 and 4). Linear mixed models revealed general evaluative conditioning effects, but inconsistent evidence for specialized (implicit or explicit) learning for a food-pathogen association. However, results from a mega-analysis across studies revealed stronger conditioning effects for meats paired with pathogen-relevant negative stimuli than pathogen-irrelevant negative stimuli.

Feeling more neutral? Evaluative conditioning can increase neutral affective reactions.

ABSTRACTWhile it is important to learn what is good and bad, can people learn what is neither? The answer to this question is not readily apparent, but it has important implications for how people learn affective responses. Six experiments examined whether evaluative conditioning (EC) can instill neutral affect. They tested four hypotheses: EC, in which novel conditioned stimuli (CSs) are paired with neutral unconditioned stimuli (USs) (1) creates neutral affect, (2) forms stronger experiences of neutrality when the number of contingent CS-US pairings is high rather than low, (3) creates positive affect, due to mere exposure, and (4) forms responses that are distinct from no US pairings. Respondents rated how positive, negative, and neutral they felt about a CS before and after an EC task in which CSs were paired with USs (positive, negative, neutral, or no stimuli). The positive/negative US conditions increased/decreased positivity, decreased/increased negativity, and decreased neutrality ratings, respectively. Supporting hypotheses 1, 2, and 4, the neutral US, but not the no US, condition increased neutral evaluations when respondents experienced a high (vs. low) number of CS-US pairings. Hypothesis 3 was not supported. The results reveal that people learn not only valenced, but also neutral, preferences.

Two roads leading to the same evaluative conditioning effect? Stimulus-response binding versus operant conditioning.

Evaluative Conditioning (EC) refers to changes in our liking or disliking of a stimulus due to its pairing with other positive or negative stimuli. In addition to stimulus-based mechanisms, recent research has shown that action-based mechanisms can also lead to EC effects. Research, based on action control theories, has shown that pairing a positive or negative action with a neutral stimulus results in EC effects (Stimulus-Response binding). Similarly, research studies using Operant Conditioning (OC) approaches have also observed EC effects. The aim of the present study is to directly compare EC effects elicited by two different response-based approaches - S-R bindings and OC. To this end, participants were randomly assigned to an S-R binding procedure and an OC procedure. EC effects were measured in conditions and compared. Implications for EC theory are discussed.

The role of category valence in prototype preference.

People prefer prototypical stimuli over atypical stimuli. The dominant explanation for this prototype preference effect is that prototypical stimuli are processed more fluently. However, a more recent account proposes that prototypes are more strongly associated with their category's valence, leading to a reversed prototype preference effect for negative categories. One critical but untested assumption of this category-valence account is that no prototype preference should emerge for entirely neutral categories. We tested this prediction by conditioning categories of dot patterns positively, negatively, or neutrally. In line with previous findings on the category-valence account, prototype preference reversed for negatively conditioned categories. However, prototype preference was similarly strong for positive and neutral categories. These findings imply that prototype preferences do not only reflect a transfer of category valence to exemplars. Instead, the results suggest that prototype preference is a multi-process phenomenon arising from the activated category valence and a fluency-based process. We discuss further implications for theories on fluency and prototype preference.

Two social minds in one brain? error-related negativity provides evidence for parallel processing pathways during social evaluation.

Several authors assume that evaluative conditioning (EC) relies on high-level propositional thinking. In contrast, the dual-process perspective proposes two processing pathways, one associative and the other propositional, contributing to EC. Dual-process theorists argue that attitudinal ambiguity resulting from these two pathways' conflicting evaluations demonstrate the involvement of both automatic and controlled processes in EC. Previously, we suggested that amplitude variations of error-related negativity and error-positivity, two well-researched event-related potentials of performance monitoring, allow for the detection of attitudinal ambiguity at the neural level. The present study utilises self-reported evaluation, categorisation performance, and neural correlates of performance monitoring to explore associative-propositional ambiguity during social attitude formation. Our results show that compared to associative-propositional harmony, attitudinal ambiguity correlates with more neutral subjective evaluations, longer response times, increased error commission, and diminished error-related negativity amplitudes. While our findings align with dual-process models, we aim to offer a propositional interpretation. We discuss dual-process theories in the context of evolutionary psychology, suggesting that associative processes may only represent a small piece of the EC puzzle.

A conditional judgment procedure for probing evaluative conditioning effects in the absence of feelings of remembering.

Attitude research has capitalized on evaluative conditioning procedures to gain insight into how evaluations are formed and may be changed. In evaluative conditioning, a conditioned stimulus (CS; e.g., an unfamiliar soda brand) is paired with an unconditioned stimulus (US) of affective value (e.g., a pleasant picture). Following this pairing, a change in CS liking may be observed (e.g., the soda brand is liked better). A question with far-reaching theoretical and practical implications is whether the change in CS liking is found when participants feel they do not remember the CS-US pairings at the time an evaluation is produced about the CS. Here, we introduce a new conditional judgment procedure-the two-button-sets (TBS) task-for probing evaluative conditioning effects without feelings of remembering about the valence of the US paired with the CS. In three experiments, the TBS is (1) is successfully validated; it is also used to (2) provide preliminary information on the feeling of remembering question, and (3) to examine an affect-consistent bias in memory judgments for CS-US pairings. Results do not support evaluative effects in the absence of feelings of remembering, and they oppose the view that affect-consistent bias is limited to memory uncertainty. We discuss these findings in light of previous evidence and of dual-learning models of attitudes. We also discuss limitations and research avenues related to the new procedure.

Sixty Years After Orne's American Psychologist Article: A Conceptual Framework for Subjective Experiences Elicited by Demand Characteristics.

Study participants form beliefs based on cues present in a testing situation (demand characteristics). These beliefs can alter study outcomes (demand effects). Neglecting demand effects can threaten the internal and external validity of studies (including their replication). While demand characteristics garnered much attention following Orne's introduction of this notion, consideration of their effects has become sparse in experimental reports. Moreover, the concept remains confusing. Here, we introduce a conceptual framework for subjective experiences elicited by demand characteristics. The model distinguishes between participants' awareness of the hypothesis, their motivation to comply with it, and the strategy they use to meet situational requirements. We stress that demand characteristics can give rise to genuine experiences. To illustrate, we apply the model to Evaluative Conditioning and the Rubber Hand Illusion. In the General Discussion, we discuss risks and opportunities associated with demand characteristics, and we explain that they remain highly relevant to current research.

Enjoy exercise more: The effects of dual-channel evaluative conditioning on implicit attitudes toward exercise.

Researchers have been looking for effective interventions to promote physical activity due to its great impact on both physical and mental health. In two studies, the current research investigated (1) whether evaluative conditioning could increase implicit attitudes toward exercise; (2) whether dual-channel evaluative conditioning had a greater influence compared to single-channel evaluative conditioning. In Study 1, results from 32 participants (7 males, 25 females; Mage = 19.470, SDage = 1.174) were used to compare the audiovisual dual-channel with the visual single-channel evaluative conditioning. In Study 2, we analyzed data from 100 participants (35 males, 65 females; Mage = 20.990, SDage = 3.141) and compared the visual-kinesthetic dual-channel with the visual single-channel evaluative conditioning. The results showed that individuals' implicit attitudes toward exercise were more positively affected by dual-channel than single-channel evaluative conditioning.

Comparing the effects of inhibitory control training and evaluative conditioning for unhealthy food behaviours.

Cognitive Bias Modification (CBM) is hypothesised to reduce unhealthy food preference and consumption through the completion of computerised cognitive training tasks. While there is evidence to suggest that two popular CBM paradigms (Inhibitory Control Training (ICT) and Evaluative Conditioning (EC)) can have a positive influence on food-related outcomes, issues (and inconsistencies) related to task standardisation and control group design make it difficult to evaluate their standalone efficacy. In a pre-registered laboratory study using a mixed experimental design, our aim was to directly compare a single session of ICT and EC on implicit preference, explicit choice and ad-libitum food intake, while ensuring appropriate active control groups were utilised for each training type (in addition to a passive control group). The results revealed that there were no significant differences in terms of implicit preferences, ad-libitum food consumption or food choice. These results provide limited evidence to support the use of CBM as a psychological intervention for unhealthy food choice or consumption. Further work is needed to isolate mechanisms of effect for successful training and identify the most effective CBM protocols for implementation in future studies.

The influence of instructions on generalised valence - conditional stimulus instructions after evaluative conditioning update the explicit and implicit evaluations of generalisation stimuli.

Generalisation in evaluative conditioning occurs when the valence acquired by a conditional stimulus (CS), after repeated pairing with an unconditional stimulus (US), spreads to stimuli that are similar to the CS (generalisation stimuli, GS). CS evaluations can be updated via CS instructions that conflict with prior conditioning (negative conditioning + positive instruction). We examined whether CS instructions can update GS evaluations after conditioning. We used alien stimuli where one alien (CSp) from a fictional group was paired with pleasant US images and another alien (CSu) from a different group was paired with unpleasant US images. The other members from the two groups were used as GSs. After conditioning, participants received negative CSp instructions and positive CSu instructions. In Experiment 1, explicit and implicit GS evaluations were measured before and after the instructions. In Experiment 2, we used a between-participants design where one group received positive/negative CS instructions while a control group received neutral instructions. In both experiments, the positive/negative CS instructions caused a reversal of explicit GS evaluations and an elimination of implicit GS evaluations. The findings suggest that generalised evaluations can change after CS instructions which may have implications for interventions aimed at reducing negative group attitudes.

Articulation dynamics and evaluative conditioning: investigating the boundary conditions, mental representation, and origin of the in-out effect.

People prefer linguistic stimuli with an inward (e.g. BODIKA) over those with an outward articulation dynamic (e.g. KODIBA), a phenomenon known as the articulatory in-out effect. Despite its robustness across languages and contexts, the phenomenon is still poorly understood. To learn more about the effect's boundary conditions, mental representation, and origin, we crossed the in-out effect with evaluative conditioning research. In five experiments (N = 713, three experiments pre-registered), we systematically paired words containing inward versus outward dynamics with pictures of negative versus positive valence. Although this evaluative conditioning procedure reversed the preference for inward over outward words, this was the case only for words with the same consonant sequences as the conditioned words. For words with inward/outward dynamics but different consonant sequences than the conditioned ones, a regular in-out effect emerged. Also, no preference reversal at all emerged for the conditioned consonant sequences when the contingency between single consonants at specific positions and positive/negative valence was zero. Implications of these findings for the in-out effect and evaluative conditioning are discussed.

Japanese written pseudowords can be conditioned to Japanese spoken words with positive, negative, and active emotions.

This study aimed to examine whether Japanese participants condition spoken words' meanings to written pseudowords. In Survey 1, we selected spoken words associated with negative (α = .91) and positive (α = .79) features for Experiment 1 and passive (α = .90) and active (α = .80) features for Experiment 2. In Experiment 1, participants evaluated four written pseudowords' emotional valence using a 7-point semantic differential scale (1: negative; 7: positive) before and after conditioning spoken words with negative, neutral, or positive features to each pseudoword. In the conditioning phase, participants read each pseudoword, listened to a spoken word, and verbally repeated each spoken word. The results showed that a pseudoword was conditioned to spoken words with positive and negative features. In Experiment 2, participants evaluated four pseudowords' activeness using a 7-point semantic differential scale (1: passive; 7: active) before and after conditioning spoken words of passive, neutral, and active features to each written pseudoword. In the conditioning phase, the participants read each written pseudoword, listened to a spoken word, and repeated the spoken word. The results showed that the activeness evaluations were more increased for pseudowords conditioned to spoken words of active and neutral features after conditioning than before conditioning but were unchanged for a pseudoword conditioned to those with passive features before and after conditioning. Additonally, Survey 2's results showed that although the positiveness and activeness responses of the words used in Experiments 1 and 2 were controlled well, the lack of significant differences among positiveness responses of words may influence the evaluative conditioning in Experiment 2. That is, when participants condition passive (low arousal) words' activeness (arousal) ratings to those of pseudowords, words' positiveness (valence) ratings would be important in the evaluative conditioning. Our findings suggest that participants can condition spoken word meanings of preference and activeness to those of written pseudowords. It also indicates that linguistically evaluative conditioning's effects are robust in a non-alphabetic language.

'Don't stop believing': The role of training beliefs in cognitive bias modification paradigms.

Cognitive Bias Modification (CBM) paradigms have previously been applied to target appetite (craving, hunger) and food intake, and are hypothesised to reduce unhealthy food consumption. However, inconsistencies in relation to training outcomes raise questions regarding the efficacy of CBM as a standalone intervention. Furthermore, individual level factors (such as belief in the intervention efficacy) may influence expectations of behaviour change following training. Across two pre-registered studies, our aim was to investigate how directly manipulating beliefs in relation to training purpose and effectiveness influenced food value and choice across two popular CBM paradigms (Inhibitory Control Training (ICT: Study 1) and Evaluative Conditioning (EC: Study 2)). In online studies, participants were presented with a paragraph describing the CBM technique positively (or an unrelated control message) prior to completing either active or control CBM training. Across both studies, the results revealed that active CBM training resulted in a reduction to unhealthy food value (relative to pre-training), but only when paired with a positive manipulation message. Participants who received a control message displayed no significant changes to food value, even where active CBM training was provided. These results suggest that participant beliefs and expectancies have important consequences for CBM effectiveness. Future research should further investigate these factors within CBM contexts to identify their role within successful behaviour change interventions.

Learning to like triangles: A longitudinal investigation of evaluative conditioning in infancy.

There is tentative evidence that infants can learn preferences through evaluative conditioning to socioemotional stimuli. However, the early development of evaluative conditioning and the factors that may explain infants' capacity to learn through evaluative conditioning are not well understood. Infants (N = 319; 50.2% boys) participated in a longitudinal study where an evaluative conditioning paradigm using socioemotional stimuli was conducted on two occasions (when infants were 7 and 14 months old, on average). We tested whether repeatedly pairing neutral stimuli (triangular and square shapes) with affective stimuli (angry and happy faces) affects infants' preferences for these shapes. At both timepoints, the majority of infants did not choose the shape that was paired with happy faces, indicating that, in general, learning through evaluative conditioning was not present. However, as expected, individual differences were evident such that infants who spent more time fixating on faces compared to shapes (face-preferrers) during the conditioning trials were significantly more likely than non-face-preferrers to choose the shape paired with happy faces, and this effect strengthened with increasing age.

Conceptual generalisation in fear conditioning using single and multiple category exemplars as conditional stimuli - electrodermal responses and valence evaluations generalise to the broader category.

Conceptual generalisation occurs when conditional responses generalise to novel stimuli from the same category. Past research demonstrates that physiological fear responses generalise across categories, however, conceptual generalisation of stimulus valence evaluations during fear conditioning has not been examined. We investigated whether conceptual generalisation, as indexed by electrodermal responses and stimulus evaluations, would occur, and differ after training with single or multiple conditional stimuli (CSs). Stimuli from two of four categories (vegetables, farm animals, clothing, and office supplies) were used as the CS+ (followed by an electric stimulus) or CS- (presented alone). Generalisation was assessed by presenting novel stimuli from the CS categories after acquisition, extinction, and reinstatement. One category exemplar was used as the CS+ and CS- in the single group, whereas three exemplars were used as the CS+ and CS- in the multiple group. Electrodermal responses generalised in acquisition and extinction but did not differ between groups. In the multiple group, CS evaluations generalised in acquisition and extinction, whereas generalisation was not evident in the single group. Training with multiple CSs also resulted in the extinction of stimulus valence. The current findings have implications for future research examining the generalisation of valence and for exposure-based treatments of anxiety.

Incidental Attitude Formation via the Surveillance Task: A Preregistered Replication of the Olson and Fazio (2001) Study.

Evaluative conditioning is one of the most widely studied procedures for establishing and changing attitudes. The surveillance task is a highly cited evaluative-conditioning paradigm and one that is claimed to generate attitudes without awareness. The potential for evaluative-conditioning effects to occur without awareness continues to fuel conceptual, theoretical, and applied developments. Yet few published studies have used this task, and most are characterized by small samples and small effect sizes. We conducted a high-powered (N = 1,478 adult participants), preregistered close replication of the original surveillance-task study (Olson & Fazio, 2001). We obtained evidence for a small evaluative-conditioning effect when "aware" participants were excluded using the original criterion-therefore replicating the original effect. However, no such effect emerged when three other awareness criteria were used. We suggest that there is a need for caution when using evidence from the surveillance-task effect to make theoretical and practical claims about "unaware" evaluative-conditioning effects.

How to promote healthy eating in preschool children: Evidence from an associative conditioning procedure with non-food stimuli.

Given the increasing rates and severe consequences of childhood obesity, how to encourage children to eat low-calorie and healthy foods is an important question. Building on evaluative conditioning research, this study investigated how associating fruits and vegetables with positive, non-food stimuli influences preschool children's food choice and consumption. Consistent with this idea, it was found in two experiments that 3- to 6-year-old children's healthy food choice and consumption increased by pairing a healthy food's picture systematically with a positive, non-food image. These findings highlight a simple yet effective means of changing young children's eating behavior, which may complement existing intervention procedures.

Examining cognitive bias modification interventions for reducing food value and choice: Two pre-registered, online studies.

There is considerable interest in Cognitive Bias Modification (CBM) as a potential treatment for overweight/obesity. Inhibitory Control Training (ICT: also known as motor response training) and Evaluative Conditioning (EC) are two popular paradigms which rely on associatively learned responses (unhealthy food - > inhibition, or unhealthy food- > negative stimulus, respectively) through repeated cue-response contingencies. Both ICT and EC have demonstrated some effectiveness for reducing food intake, value and/or choice, when administered in the laboratory and online. However, studies have been criticised for inconsistencies in design (e.g. use of inadequate control groups) which makes it difficult to draw robust conclusions. In two pre-registered, online studies our aim was to examine active ICT (study 1: N = 170) and EC (study 2: N = 300) in multiple groups where the cue- > response contingencies were systematically varied (100%, 75%, 50%, 25%), before examining food-cue valuations and hypothetical food choice. In both studies varying the cue- > response contingencies did not lead to significant changes in food-cue devaluation following training. ICT did not substantially influence hypothetical food choice, whereas there was weak evidence that EC reduced choice for unhealthy foods, compared to a control group with 50% cue-response contingencies. Taken together both studies provide limited evidence for online CBM as a viable psychological treatment - at least through the mechanism of food-cue devaluation or changes in healthy and unhealthy food choice. Future research is needed to investigate the factors that contribute towards successful CBM training to critically evaluate the potential for these strategies within interventions.

No evidence of consolidation of evaluative conditioning during waking rest and sleep.

Research on evaluative conditioning (EC) shows that attitudes can emerge from co-occurrences of stimuli, and accumulating evidence suggests that EC usually depends on memory for these stimulus contingencies. Therefore, processes known to aid memory retention may be relevant for the development of stable attitudes. One such process may be memory consolidation, assumed to be promoted by waking rest and sleep. In two pre-registered experiments, we investigated whether waking rest (vs. cognitive activity, Experiment 1) and sleep (vs. wakefulness, Experiment 2) in between conditioning and measurement of EC, consolidate contingency memory and EC. Contrary to our predictions, waking rest (vs. cognitive activity) promoted neither contingency memory nor EC effects. Sleep (vs. wakefulness) decreased forgetting of contingency memory but crucially, it did not attenuate the impact of counterconditioning on contingency memory. Sleep also did not influence EC effects, nor the reduction of EC by counterconditioning. EC effects in both experiments were predicted by contingency memory. Yet, unexpectedly, EC effects occurred in the absence of contingency memory after waking rest, but neither after sleep nor in the active control conditions. Our findings emphasise a role of contingency memory in EC, but it remains unclear whether this role changes during waking rest.