Biases in probabilistic category learning in relation to social anxiety

Abstract

Instrumental learning paradigms are rarely employed to investigate the mechanisms underlying acquired fear responses in social anxiety. Here, we adapted a probabilistic category learning paradigm to assess information processing biases as a function of the degree of social anxiety traits in a sample of healthy individuals without a diagnosis of social phobia. Participants were presented with three pairs of neutral faces with differing probabilistic accuracy contingencies (A/B: 80/20, C/D: 70/30, E/F: 60/40). Upon making their choice, negative and positive feedback was conveyed using angry and happy faces, respectively. The highly socially anxious group showed a strong tendency to be more accurate at learning the probability contingency associated with the most ambiguous stimulus pair (E/F: 60/40). Moreover, when pairing the most positively reinforced stimulus or the most negatively reinforced stimulus with all the other stimuli in a test phase, the highly socially anxious group avoided the most negatively reinforced stimulus significantly more than the control group. The results are discussed with reference to avoidance learning and hypersensitivity to negative socially evaluative information associated with social anxiety.

Keywords: information processing biases; instrumental learning; positive versus negative feedback; probabilistic learning; reinforcement learning; social anxiety.

FIGURE 1

Sequence of trial events. (Top) The representation of trial events in the Learning Phase of the study. Each trial begins with a blank screen which is presented for 2300 ms, followed by a pair of neutral face stimuli for 1500 ms. Subjects are instructed to indicate with a key press (left or right) which of the two faces is the correct option in the current trial. Based on the accuracy of the subject’s choice, s/he is given positive feedback (happy face) or negative feedback (angry face) that is presented for 700 ms between the neutral face stimuli. If the subjects take too long to respond, they receive feedback in the form of a message between the neutral face stimuli stating “Oops! Too Late” (not shown in the Figure). This is followed by the presentation of a blank screen (2300 ms) which marks the commencement of the next trial. (Bottom) The representation of trial events during the Test Phase of the study. Each trial begins with a blank screen which is presented for 2300 ms, followed by a pair of neutral face stimuli for 1500 ms. Subjects are instructed to indicate with a key press (left or right) which of the two presented neutral faces is the correct option. No feedback on the responses is given within the test phase. This is followed by the presentation of a blank screen (2300 ms) which marks the commencement of the next trial.

FIGURE 2

(A) Findings from the self-assessment manikin (SAM) ratings (Mean ± 1 SE) of the face stimuli on Valence (pleasant–unpleasant). Angry faces were rated to be significantly more unpleasant than the happy and neutral faces, and neutral faces were rated as significantly more unpleasant than happy faces (all p < 0.001). (B) Findings from the SAM ratings (Mean ± 1 SE) of the face stimuli on Arousal (calm to excited). Angry faces were rated to be significantly more arousing than the happy and neutral faces (all p < 0.001). The HSA reported a generally higher level of arousal when viewing the face stimuli than the NSA (p < 0.05). (C) Results from the Learning Phase showing successful learning (percentage accuracy: Mean ± 1 SE) of the probabilistic task. On being presented with the three probabilistic pairs (AB, CD, EF), the high probability stimuli (A, C, E) within each pair (dark line) were selected more often than their corresponding low probability stimuli (B, D, F; light line). Differences in probability contingencies of the stimuli were also successfully learnt (A > C > E > F > D > B). (D) Results from the Learning Phase (Mean ± 1 SE) showing that the HSA more accurately detected the actual probability difference between the EF pair than the NSA. (E) Results from the Test Phase (Mean ± 1 SE) showing that the HSA group avoided B, the most punished stimulus, significantly more than the NSA (*p < 0.05).