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Purpose: Eating disorders (ED) and social anxiety disorder are highly comorbid with potentially shared symptoms like social appearance anxiety (SAA) referring to a fear of being negatively evaluated by others' because of overall appearance. SAA constitutes a risk factor for eating psychopathology and bridges between EDs and social anxiety disorder., Methods: The present studies examined internal consistency, factor structure, test-retest reliability, gender and age invariance, convergent validity and differences between individuals with and without an ED of a German version of the social appearance anxiety scale (SAAS) in four independent samples (n 1  = 473; n 2  = 712; n 3  = 79; n 4  = 33) including adolescents and patients with EDs., Results: Consistently, the SAAS showed excellent internal consistency (ωs ≥ 0.947) and a one-factorial structure. Convergent validity was shown via high correlations of the SAAS with social anxiety (e.g., social interaction anxiety r = 0.642; fear of negative evaluation rs ≥ 0.694), body image disturbance measures (e.g., shape concerns rs ≥ 0.654; weight concerns rs ≥ 0.607; body avoidance rs ≥ 0.612; body checking rs ≥ 0.651) and self-esteem (r = -0.557) as well as moderate correlations with general eating psychopathology (e.g., restrained rs ≥ 0.372; emotional r = 0.439; external eating r = 0.149). Additionally, the SAAS showed gender and age invariance and test-retest reliability after 4 weeks with r = 0.905 in Study 2 and was able to discriminate between individuals with and without an ED in Study 4., Conclusion: Hence, the German version of the SAAS can reliably and validly assess SAA in female and male adolescents or adults with or without an ED. Additionally, the SAAS might be used in a therapeutic context to especially target patient groups suffering from EDs with comorbid social anxiety., Level of Evidence: Level III: Evidence obtained from cohort or case-control analytic studies., (© 2021. The Author(s).)

Maladaptive avoidance behaviour, a key symptom of anxiety-related disorders, prevents extinction learning and maintains anxiety. Individual personality traits likely influence avoidance propensity: high sensation-seeking may decrease avoidance, thereby increasing extinction, and neuroticism may have the reverse effect. However, research on this is scarce. Using a naturalistic conditioned avoidance paradigm, 163 women underwent differential fear acquisition to a conditioned stimulus (CSplus). Next, during extinction, participants could either choose a risky shortcut, anticipating shock signalled by CSplus, or a time-consuming avoidance option (lengthy detour). Across participants, increased skin conductance (SCR) acquisition learning predicted subsequent instrumental avoidance. Avoidance, in turn, predicted elevated post-extinction SCR and shock-expectancy, i.e., 'protection-from-extinction'. Mediation analyses revealed that sensation seeking decreased protection-from-extinction-both for shock-expectancy and SCR-via attenuating avoidance. Neither sensation seeking nor neuroticism were related to acquisition learning and neuroticism was neither related to avoidance nor extinction. Transcranial direct currentstimulation administered before extinction did not influence present results. Results highlight the important role of elevated avoidance propensity in fear maintenance. Results moreover provide evidence for reduced sensation-seeking and increased acquisition learning to be avoidance-driving mechanisms. Since approach-avoidance conflicts are faced by anxiety patients on a daily basis, strengthening sensation-seeking-congruent attitudes and approach behaviours may optimize individualized treatment., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Deficient extinction learning has been suggested as an important mechanism involved in the etiology of posttraumatic stress disorder. A key feature of posttraumatic stress disorder, reexperiencing the trauma in form of intrusions, may be linked to deficient extinction learning. This link is investigated in a novel, functional magnetic resonance imaging-compatible fear conditioning procedure that uses trauma films. Based on previous results, we expected deficient fear extinction indexed by exaggerated responding in the anterior insula and dorsal anterior cingulate cortex to predict subsequent intrusions., Methods: A total of 58 healthy participants underwent acquisition and extinction learning with faces as conditioned stimuli (CS) and highly aversive 16-second films depicting interpersonal violence as unconditioned stimuli. During the subsequent 3 days, participants reported intrusive memories on their smartphone., Results: Successful fear acquisition was evidenced by differential (CS+ > CS-) activity (threat cues associated with trauma films > cues paired only with neutral films) of a widespread network, including the anterior insula and dorsal anterior cingulate cortex, whereas extinction was characterized exclusively by differential anterior insula activity. Differential conditioned responding during late extinction in the anterior insula and dorsal anterior cingulate cortex was positively related to intrusive memory frequency independent of unconditioned stimuli responding. Exploratory analysis also revealed intrusion sensitivity of the hippocampus, rostral anterior cingulate cortex, and ventromedial prefrontal cortex, among others., Conclusions: Results support the role of extinction learning in intrusive memory formation; a failure to uncouple conditioned emotional responding from external threat cues was associated with subsequent intrusive memories, representing a potential risk marker for developing posttraumatic stress disorder symptomatology after trauma., (Copyright © 2020 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Higher prevalence of posttraumatic stress disorder (PTSD) in women than men may be explained by sex differences in fear learning processes. Initial evidence points to elevated unconditioned and conditioned fear responding as well as to elevated state anxiety in women as potential peritraumatic mechanisms. Using the "conditioned-intrusion-paradigm", which combines differential fear conditioning with the trauma-film paradigm, neutral sounds were presented as predictors of the occurrence (CS+) or non-occurrence (CS-) of highly aversive films. Intrusions were elicited by these sounds in the laboratory after conditioning and naturalistic intrusions were assessed in daily-life on subsequent days. Compared to men (n = 62), women (n = 60) reported more intrusions and associated distress following analogue trauma. Sex differences in intrusive symptoms were mediated by a) higher unconditioned trauma responding, b) slowed extinction of differential CS valence ratings, and c) elevated state anxiety increase across conditioning in women. Secondary analyses revealed that state anxiety was the strongest mediator, followed by slowed extinction learning. Mediation models were unrelated to sex differences in trait anxiety or depressive symptoms. Thus, associative (extinction learning) and non-associative (state anxiety, trauma responding) mechanisms contribute to sex differences in intrusive symptoms after analogue trauma and might add to the heightened vulnerability to PTSD in women., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Social anxiety disorder (SAD) is marked by persistent fear of being scrutinized by others. This and most diagnostic symptoms relate to some form of fear of negative evaluation (FNE). More recent accounts of SAD, such as the Bivalent Fear of Evaluation Model, however, complement FNE with fear of positive evaluation (FPE), described as distress and avoidance of positive feedback. An explicit test of the incremental validity of FPE in discriminating SAD patients from controls - over and on top of the explanatory power of FPE - is currently missing and generally, well controlled laboratory experiments with positive and negative social stimuli in this patient group are rare. To fill this gap, we exposed 35 patients with SAD and healthy controls (HCs) to short social-evaluative video clips with actors expressing negative and positive as well as neutral statements while recording reactivity on experiential measures (valence, arousal, and approval ratings) as well as on facial electromyography and electrocardiography. In addition, participants completed questionnaire measures of FNE and FPE. Results revealed that FPE questionnaire scores as well as experiential (valence and appreciation) and electromyographical reactivity measures to positive videos improved prediction of group membership beyond the predictive power of FNE questionnaires scores and reactivity to negative videos. Results document the importance of FPE to more fully characterize and understand social anxiety and SAD. Implications include amendments to future diagnostic criteria, theoretical models, and treatment approaches for SAD., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Social anxiety is characterized by a fear of being negatively evaluated by others (i.e., Fear of Negative Evaluation [FNE]). In 2008, Weeks, Heimberg, and Rodebaugh proposed Fear of Positive Evaluation (FPE) as a second cognitive component in social anxiety. The article presents an overview of FPE, its psycho-evolutionary theoretical foundation and assessment by the Fear of Positive Evaluation Scale as well as relevant psychometric research on demographic characteristics. The relationship of FPE with a wide range of established dimensions from clinical, personality, and social psychology (i.e., self-esteem, perfectionism, or quality of life) will be reviewed. The role of FPE for psychological comorbidities such as other anxiety disorders, depression, eating, and substance use disorders as well as for treatment of social anxiety will be discussed. Future research might address questions of causality of FPE relative to related constructs, further data on psychometric properties, as well as on its independence from FNE in longitudinal studies. In sum, FPE seems to be a valid and reliable construct that explains cognitions, emotions, and behavior related to social anxiety at subclinical and clinical levels and therefore enriches the psychometric repertoire in the fields of social psychology, personality, and clinical psychology., (© 2018 The Authors. Depression and Anxiety published by Wiley Periodicals, Inc.)

Background and Objectives: Social interactions inevitably go along with repeated evaluations. Some individuals are particularly sensitive to social evaluations: Psychometric studies suggest stable and distinct individual differences on fear of negative evaluations (FNE) and fear of positive evaluation (FPE). However, little is known about day-to-day correlates of FNE and FPE, particularly their respective contribution to positive/negative affect level and affect reactivity to different stressor types., Design: Two studies naturalistically assessed the level of negative/positive affect and its reactivity to different stressor types (from distant or close social network, work and daily hassles, assessed daily) as a function of FNE/FPE., Method: Ecological Momentary Assessment employed five daily prompts during 12/10 days in convenience samples of 50/59 participants., Results: FNE predicted lower positive affect level only in Study 2. Consistent across studies negative affect reactivity to stressors emanating from the distant social network was increased in individuals high in FNE or FPE., Conclusions: Results document the relevance of both types of evaluation fears (FNE/FPE) for day-to-day affect and stress reactivity. They further specify whose evaluations are well tolerated (close network) or feared (distant network), thereby refining current psycho-evolutionary accounts of FNE/FPE.

Theoretical models specifying the underlying mechanisms of the development and maintenance of anxiety and related disorders state that fear responses acquired through classical Pavlovian conditioning are maintained by repeated avoidance behaviour; thus, it is assumed that avoidance prevents fear extinction. The present study investigated behavioural avoidance decisions as a function of avoidance costs in a naturalistic fear conditioning paradigm. Ecologically valid avoidance costs - manipulated between participant groups - were represented via time-delays during a detour in a gamified computer task. After differential acquisitions of shock-expectancy to a predictive conditioned stimulus (CS+), participants underwent extinction where they could either take a risky shortcut, while anticipating shock signaled by the CS+, or choose a costly avoidance option (lengthy detour); thus, they were faced with an approach-avoidance conflict. Groups with higher avoidance costs (longer detours) showed lower proportions of avoiders. Avoiders gave heightened shock-expectancy ratings post-extinction, demonstrating 'protecting from extinction', i.e. failure to extinguish. Moreover, there was an indirect effect of avoidance costs on protection from extinction through avoidance behaviour. No moderating role of trait-anxiety was found. Theoretical implications of avoidance behaviour are discussed, considering the involvement of instrumental learning in the maintenance of fear responses., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Depression is characterized by depressed mood and loss of interest or pleasure. Resulting alterations in emotional reactivity have been explained by three different accounts: 'positive attenuation', 'negative potentiation', and 'emotion context insensitivity'. Despite the importance of depression-related emotional alteration in social interactions, research with naturalistic interpersonal stimuli is scarce and underlying mechanisms largely unknown., Methods: Hence, the present study examined subjective emotional reactivity to brief negative, positive, and neutral social-evaluative videos as a function of depressive symptoms in an adult sample (N = 84). Fear of positive evaluation (FPE) and fear of negative evaluation (FNE), often conceptualized as cognitive components of social anxiety, were examined as possible mediators., Results: Results revealed that more depression symptoms were related to diminished pleasantness responses to both positive and neutral videos. When considering all three video conditions simultaneously, only responses to positive videos remained significantly related to depression scores, supporting the 'positive attenuation' account. Moreover, FPE was found to uniquely mediate the relationship between depressive symptoms and pleasantness responses to positive videos., Conclusions: Results indicate that emotional reactivity to positive interpersonal stimuli is relevant for theoretical and clinical considerations of depression. This research underlines the importance of FPE not only for understanding social anxiety but also depression., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background and Objectives: The bivalent fear of evaluation (BFOE) model suggests that fears of negative evaluation (FNE) and positive evaluation (FPE) are distinct features in social anxiety disorder as well as in non-clinical variations of social anxiety. The constructs can be measured utilizing the Brief Fear of Negative Evaluation Scale – Revised (BFNE-R) and the Fear of Positive Evaluation Scale (FPES), respectively. Whereas the distinction between FNE and FPE has been well examined in survey studies, concomitant evidence from laboratory tasks is scarce., Methods: The present study tested whether subjective unpleasantness responses to short films simulating positive and negative evaluation from others are related to individual differences in FNE and FPE. Ninety-eight unselected individuals watched 24 short films displaying actors expressing positive, negative and neutral sentences and rated their responses on unpleasantness. Furthermore, pride responses to positive films were examined since these can be expected to discriminate between FPE and FNE., Results: As expected, higher BFNE-R scores were related to more unpleasant responding to negative films, whereas higher FPES scores were related to more unpleasant responding to positive films. Furthermore, experience of pride following positive films correlated positively with BFNE-R, but negatively with FPES scores., Limitations: Participants were university students which limits representativeness., Conclusions: The study revealed that measures of FNE and FPE show distinct relationships with positive and negative social feedback which provides further evidence for the BFOE model in a laboratory setting.

Background: The neuroplasticity hypothesis of major depressive disorder proposes that a dysfunction of synaptic plasticity represents a basic pathomechanism of the disorder. Animal models of depression indicate enhanced plasticity in a ventral emotional network, comprising the amygdala. Here, we investigated fear extinction learning as a non-invasive probe for amygdala-dependent synaptic plasticity in patients with major depressive disorder and healthy controls., Methods: Differential fear conditioning was measured in 37 inpatients with severe unipolar depression (International Classification of Diseases, 10th revision, criteria) and 40 healthy controls. The eye-blink startle response, a subcortical output signal that is modulated by local synaptic plasticity in the amygdala in fear acquisition and extinction learning, was recorded as the primary outcome parameter., Results: After robust and similar fear acquisition in both groups, patients with major depressive disorder showed significantly enhanced fear extinction learning in comparison to healthy controls, as indicated by startle responses to conditioned stimuli. The strength of extinction learning was positively correlated with the total illness duration., Conclusions: The finding of enhanced fear extinction learning in major depressive disorder is consistent with the concept that the disorder is characterized by enhanced synaptic plasticity in the amygdala and the ventral emotional network. Clinically, the observation emphasizes the potential of successful extinction learning, the basis of exposure therapy, in anxiety-related disorders despite the frequent comorbidity of major depressive disorder.

Posttraumatic stress disorder (PTSD) can be conceptualized as a disorder of emotional memory showing strong (conditioned) responses to trauma reminders and intrusive memories among other symptoms. Women are at greater risk of developing PTSD than men. Recent studies have demonstrated an influence of ovarian steroid hormones in both fear conditioning and intrusive memory paradigms. However, although intrusive memories are considered non-extinguished emotional reactions to trauma reminders, none of the previous studies has investigated effects of ovarian hormones on fear conditioning mechanisms and intrusive memories in conjunction. This may have contributed to an overall inconsistent picture of the role of these hormones in emotional learning and memory. To remedy this, we exposed 37 healthy women with a natural menstrual cycle (during early follicular or luteal cycle phase) to a novel conditioned-intrusion paradigm designed to model real-life traumatic experiences. The paradigm included a differential fear conditioning procedure with short violent film clips as unconditioned stimuli. Intrusive memories about the film clips were assessed ambulatorily on subsequent days. Women with lower levels of estradiol displayed elevated differential conditioned skin conductance responding during fear extinction and showed stronger intrusive memories. The inverse relationship between estradiol and intrusive memories was at least partially accounted for by the conditioned responding observed during fear extinction. Progesterone levels were not associated with either fear acquisition/extinction or with intrusive memories. This suggests that lower levels of estradiol might promote stronger symptoms of PTSD through associative processes., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Intrusive memories--a hallmark symptom of posttraumatic stress disorder (PTSD)--are often triggered by stimuli possessing similarity with cues that predicted or accompanied the traumatic event. According to learning theories, intrusive memories can be seen as a conditioned response to trauma reminders. However, direct laboratory evidence for the link between fear conditionability and intrusive memories is missing. Furthermore, fear conditioning studies have predominantly relied on standardized aversive stimuli (e.g. electric stimulation) that bear little resemblance to typical traumatic events. To investigate the general relationship between fear conditionability and aversive memories, we tested 66 mentally healthy females in a novel conditioned-intrusion paradigm designed to model real-life traumatic experiences. The paradigm included a differential fear conditioning procedure with neutral sounds as conditioned stimuli and short violent film clips as unconditioned stimuli. Subsequent aversive memories were assessed through a memory triggering task (within 30 minutes, in the laboratory) and ambulatory assessment (involuntary aversive memories in the 2 days following the experiment). Skin conductance responses and subjective ratings demonstrated successful differential conditioning indicating that naturalistic aversive film stimuli can be used in a fear conditioning experiment. Furthermore, aversive memories were elicited in response to the conditioned stimuli during the memory triggering task and also occurred in the 2 days following the experiment. Importantly, participants who displayed higher conditionability showed more aversive memories during the memory triggering task and during ambulatory assessment. This suggests that fear conditioning constitutes an important source of persistent aversive memories. Implications for PTSD and its treatment are discussed.

The present study investigated reinstatement of fear in humans using an aversive differential conditioning paradigm. Two neutral human face pictures were presented during habituation, acquisition, extinction, and postreinstatement phases. One picture served as a conditioned stimulus (CS) reinforced by an unconditioned stimulus (US) in the form of electrical stimulation (CS+) and the second picture as a control stimulus that was never reinforced (CS-). The prediction that in a reinstatement manipulation a previously extinguished fear response in humans can be reinstated in a reinstatement group by the mere presentation of three unpredicted electrical stimulations (USs) was tested. Participants in the control group were not exposed to unpredicted USs and no reinstatement effect was expected. Outcome measures included subjective US expectancy ratings and skin conductance responses. Results showed non-selective return of the fear response due to fear recovery associated with both CSs (CS+/CS-) in the reinstatement group. Unexpected fear recovery was observed for both CSs (CS+/CS-) in control participants. Results are discussed with respect to context conditioning, fear generalisation, and anxiety-related cognitive mechanisms underlying fear recovery after extinction., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Recent studies have begun to carve out a specific role for the rostral part of the dorsal medial prefrontal cortex (dmPFC) and adjacent dorsal anterior cingulate cortex (dACC) in fear/anxiety. Within a novel general framework of dorsal mPFC/ACC areas subserving the appraisal of threat and concomitant expression of fear responses and ventral mPFC/ACC areas subserving fear regulation, the rostral dmPFC/dACC has been proposed to specifically mediate the conscious, negative appraisal of threat situations including, as an extreme variant, catastrophizing. An alternative explanation that has not been conclusively ruled out yet is that the area is involved in fear learning. We tested two different fear expression paradigms in separate fMRI studies (study 1: instructed fear, study 2: testing of Pavlovian conditioned fear) with independent groups of healthy adult subjects. In both paradigms the absence of reinforcement precluded conditioning. We demonstrate significant BOLD activation of an identical rostral dmPFC/dACC area. In the Pavlovian paradigm (study 2), the area only activated robustly once prior conditioning had finished. Thus, our data argue against a role of the area in fear learning. We further replicate a repeated observation of a dissociation between peripheral-physiological fear responding and rostral dmPFC/dACC activation, strongly suggesting the area does not directly generate fear responses but rather contributes to appraisal processes. Although we succeeded in preventing extinction of conditioned responding in either paradigm, the data do not allow us to definitively exclude an involvement of the area in fear extinction learning. We discuss the broader implications of this finding for our understanding of mPFC/ACC function in fear and in negative emotion more generally.

Objective: Fear conditionability has been found to be elevated in samples with high trait anxiety or anxiety disorders. Since these studies provide circumstantial evidence for a causal link between anxiety and conditionability we examined fear conditionability after experimental induction of anxiety in two experiments., Method: In Experiment 1, 60 participants were randomized to one of two film conditions inducing an anxious or happy emotional state. They subsequently underwent a differential conditioning acquisition procedure. Two pictures of faces served as conditioned stimuli (CS+ and CS-), and an electric stimulus served as aversive unconditioned stimulus (US). In Experiment 2, after similar acquisition procedure as used in Experiment 1, 90 participants watched one of three films (anxious, neutral, happy) prior to an extinction procedure. In both studies, skin conductance response (SCR) served as measure of fearful responding., Results: Conditioning was successful in both studies. In Experiment 1, the anxious group exhibited decreased SCRs to both CS+ and CS- during acquisition. In Experiment 2, during extinction SCRs to both CSs were highest in the anxious group, intermediate in the neutral, and lowest in the happy group., Discussion: State anxiety did not enhance conditionability during acquisition or reduce the extinction procedure. However, individuals in an anxious state show less responding during fear learning, but more responding during unlearning. Thus, our results suggest that state anxiety changes the sensitivity with which individuals react to stimuli presented in different contexts., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Anticipatory emotional responses play a crucial role in preparing individuals for impending challenges. They do this by triggering a coordinated set of changes in behavioral, autonomic, and neural response systems. In the present study, we examined the biobehavioral impact of varying levels of anticipatory anxiety, using a shock anticipation task in which unpredictable electric shocks were threatened and delivered to the wrist at variable intervals and intensities (safe, medium, strong). This permitted investigation of a dynamic range of anticipatory anxiety responses. In two studies, 95 and 51 healthy female participants, respectively, underwent this shock anticipation task while providing continuous ratings of anxiety experience and electrodermal responding (Study 1) and during fMRI BOLD neuroimaging (Study 2). Results indicated a step-wise pattern of responding in anxiety experience and electrodermal responses. Several brain regions showed robust responses to shock anticipation relative to safe trials, including the hypothalamus, periaqueductal gray, caudate, precentral gyrus, thalamus, insula, ventrolateral PFC, dorsomedial PFC, and ACC. A subset of these regions demonstrated a linear pattern of increased responding from safe to medium to strong trials, including the bilateral insula, ACC, and inferior frontal gyrus. These responses were modulated by individual differences in neuroticism, such that those high in neuroticism showed exaggerated anxiety experience across the entire task, and reduced brain activation from medium to strong trials in a subset of brain regions. These findings suggest that individual differences in neuroticism may influence sensitivity to anticipatory threat and provide new insights into the mechanism through which neuroticism may confer risk for developing anxiety disorders via dysregulated anticipatory responses., (Copyright © 2010 Elsevier Inc. All rights reserved.)

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.

Enhanced conditionability has been proposed as a crucial factor in the etiology and maintenance of panic disorder (PD). To test this assumption, the authors of the current study examined the acquisition and extinction of conditioned responses to aversive stimuli in PD. Thirty-nine PD patients and 33 healthy control participants took part in a differential aversive conditioning experiment. A highly annoying but not painful electrical stimulus served as the unconditioned stimulus (US), and two neutral pictures were used as either the paired conditioned stimulus (CS+) or the unpaired conditioned stimulus (CS-). Results indicate that PD patients do not show larger conditioned responses during acquisition than control participants. However, in contrast to control participants, PD patients exhibited larger skin conductance responses to CS+ stimuli during extinction and maintained a more negative evaluation of them, as indicated by valence ratings obtained several times throughout the experiment. This suggests that PD patients show enhanced conditionability with respect to extinction.