Trait anxiety is associated with reduced typicality asymmetry in fear generalization

Unconditioned stimulus devaluation decreases the generalization of costly safety behaviors

Safety behaviors are often maladaptive in clinical anxiety as they typically persist without realistic threat and cause various impairments. In the laboratory, safety behaviors are modelled by responses to a conditioned stimulus (CS) that reduce the occurrence of an expected aversive unconditioned stimulus (US). Preliminary evidence suggests that US devaluation, a procedure that decreases US aversiveness, devalues the threat value of the CS and thus diminishes safety behaviors to the CS. This study (n = 78) aimed to extend this finding and examined whether US-devaluation can reduce the generalization of safety behaviors to various stimuli. After acquiring safety behaviors to CSs of different categories, the US predicted by one CS category was devalued. In test, participants showed a selective reduction in safety behaviors to novel stimuli of the devalued CS category, reflecting a decrease in generalization of safety behaviors. Trait anxiety was associated with persistent generalized safety behaviors to novel stimuli of the devalued category. We discuss how US devaluation may improve treatment outcome but also the challenges of clinical translation.

Impact of observational and direct learning on fear conditioning generalization in humans

Humans gain knowledge about threats not only from their own experiences but also from observing others' behavior. A neutral stimulus is associated with a threat stimulus for several times and the neutral stimulus will evoke fear responses, which is known as fear conditioning. When encountering a new event that is similar to one previously associated with a threat, one may feel afraid and produce fear responses. This is called fear generalization. Previous studies have mostly focused on fear conditioning and generalization based on direct learning, but few have explored how observational fear learning affects fear conditioning and generalization. To the best of our knowledge, no previous study has focused on the neural correlations of fear conditioning and generalization based on observational learning. In the present study, 58 participants performed a differential conditioning paradigm in which they learned the associations between neutral cues (i.e., geometric figures) and threat stimuli (i.e., electric shock). The learning occurred on their own (i.e., direct learning) and by observing other participant's responses (i.e., observational learning); the study used a within-subjects design. After each learning condition, a fear generalization paradigm was conducted by each participant independently while their behavioral responses (i.e., expectation of a shock) and electroencephalography (EEG) recordings or responses were recorded. The shock expectancy ratings showed that observational learning, compared to direct learning, reduced the differentiation between the conditioned threatening stimuli and safety stimuli and the increased shock expectancy to the generalization stimuli. The EEG indicated that in fear learning, threatening conditioned stimuli in observational and direct learning increased early discrimination (P1) and late motivated attention (late positive potential [LPP]), compared with safety conditioned stimuli. In fear generalization, early discrimination, late motivated attention, and orienting attention (alpha-event-related desynchronization [alpha-ERD]) to generalization stimuli were reduced in the observational learning condition. These findings suggest that compared to direct learning, observational learning reduces differential fear learning and increases the generalization of fear, and this might be associated with reduced discrimination and attentional function related to generalization stimuli.

Pavlovian Disgust Conditioning and Generalization: Specificity and Associations With Individual Differences

Although studies have identified differences between fear and disgust conditioning, much less is known about the generalization of conditioned disgust. This is an important gap in the literature given that overgeneralization of conditioned disgust to neutral stimuli may have clinical implications. To address this knowledge gap, female participants (n = 80) completed a Pavlovian conditioning procedure in which one neutral food item (conditioned stimulus; CS+) was followed by disgusting videos of individuals vomiting (unconditioned stimulus; US) and another neutral food item (CS-) was not reinforced with the disgusting video. Following this acquisition phase, there was an extinction phase in which both CSs were presented unreinforced. Importantly, participants also evaluated generalization stimuli (GS+, GS-) that resembled, but were distinct from, the CS after each conditioning phase. As predicted, the CS+ was rated as significantly more disgusting and fear inducing than the CS- after acquisition and this pattern persisted after extinction. However, disgust ratings of the CS+ after acquisition were significantly larger than fear ratings. Participants also rated the GS+ as significantly more disgusting, but not fear inducing, than the GS- after acquisition. However, this effect was not observed after extinction. Disgust proneness did predict a greater increase in disgust and fear ratings of the CS+ relative to the CS- after acquisition and extinction. In contrast, trait anxiety predicted only higher fear ratings to the CS+ relative to the CS- after acquisition and extinction. Disgust proneness nor trait anxiety predicted the greater increase in disgust to the GS+ relative to the GS- after acquisition. These findings suggest that while conditioned disgust can generalize, individual difference variables that predict generalization remain unclear. The implications of these findings for disorders of disgust are discussed.

Stimulus diversity increases category-based fear generalization and the effect of intolerance of uncertainty

Fear generalization refers to conditioned fear responses extending to related stimuli and fear overgeneralization is a key feature of pathological anxiety. Along with perception similarity, conceptual relations affect fear generalization. We investigated whether stimulus diversity-an important principle of category-based induction-influences fear generalization. Induction studies have shown that generalization from a premise involving diverse instances is stronger than that from non-diverse instances. We adopted this framework for fear learning and established two groups. The diverse group developed fear in response to diverse instances from one category, while the non-diverse group acquired fear of non-diverse instances from the same category. An effect of stimulus diversity was observed in shock-expectancy ratings, with the diverse group displaying higher fear generalization than the non-diverse group. We also tested whether intolerance of uncertainty (IU) might affect the difference in fear generalization between the two conditions. Individuals with higher IU showed reduced difference in fear generalization between two conditions, mainly driven by heightened fear generalization to novel stimulus with ambiguous threat levels in the non-diverse condition. This study helps illustrate the mechanisms behind differential category-based fear generalization and provides a potential explanation for why higher IU individuals may develop anxiety disorders following trauma.