The impact of induced anxiety on affective response inhibition
Studying the effects of experimentally induced anxiety in healthy volunteers may increase our understanding of the mechanisms underpinning anxiety disorders. Experimentally induced stress (via threat of unpredictable shock) improves accuracy at withholding a response on the Sustained Attention to Response Task (SART), and in separate studies improves accuracy to classify fearful faces, creating an affective bias. Integrating these findings, participants at two public science engagement events (N=46, N=55) were recruited to explore the effects of experimentally induced stress on an affective version of the SART. We hypothesised that we would see an improved accuracy at withholding a response to affectively congruent stimuli (i.e. increased accuracy at withholding a response to fearful ‘no-go’ distractors) under threat of shock. Induced anxiety slowed reaction time, and at the second event quicker responses were made to fearful stimuli. However, we did not observe improved inhibition overall during induced anxiety, and there was no evidence to suggest an interaction between induced anxiety and stimulus valence on response accuracy. Indeed Bayesian analysis provided decisive evidence against this hypothesis. We suggest that the presence of emotional stimuli might make the safe condition more anxiogenic, reducing the differential between conditions, and knocking out any threat-potentiated improvement.
Prior to analysis, a log transform was applied to reaction time data as it was not normally distributed. Reaction time (RT) analysis was performed on ‘go’ stimuli only (as the only RTs on ‘no-go’ trials are error trials). Reaction time to ‘go’ stimuli was analysed using a two-way ANOVA with factors valence (happy / sad) and condition (threat / safe). Accuracy analysis was performed on ‘no-go’ trials only (‘go’ accuracy was 95.2 % and 97.1% at the first and second event, respectively). Performance accuracy for each condition (threat/safe) and trial type (‘go’ / ‘no-go’) was calculated by dividing the number of correct trials by the total number of trials. Response accuracy on ‘no-go’ trials was analysed using a two-way ANOVA with factors valence (happy / sad) and condition (threat / safe). For all analyses, p = 0.05, was considered significant.