Abstract
We evaluated the effects of alcohol, expectancy, threat of shock, and valence of competing visual stimuli on fear potentiated startle (FPS), the difference between startle magnitude under threat conditions and that under safe conditions, with startle assessed via recording of its eyeblink component. Equal numbers of men and women were assigned to one of three beverage conditions: moderate dose of alcohol, placebo, or no-alcohol. For half of the trial blocks, participants were under the threat of electric shock; for half, they were safe from shock. Within each block, participants viewed intermittent pictures of varied emotional content. In half of the trial blocks, the pictures were pleasant; in half, they were unpleasant. Startle probes were introduced both during picture presentations and during the inter-trial intervals (ITIs). This method provided an opportunity to compare pertinent, but somewhat disparate, hypotheses regarding the anxiolytic effect of alcohol and factors affecting it derived from the Stress Response Dampening (SRD), the Multidimensional-Multilevel (MD-ML) and the Attention-Allocation (AT-AL) models of alcohol’s effect on affective responses. Specifically, SRD predicted a main effect of alcohol in reducing FPS, irrespective of the presence of distracters designed to capture attention; MD-ML predicted that the presence of any distracter, regardless of valence, would reduce FPS; AT-AL predicted that the valence of distracters would influence their impact on FPS such that pleasant distracters should decrease it, whereas unpleasant distracters would increase it. Results, which included a novel demonstration of a significant “crying-in-your-beer” effect (elevation of FPS in the presence of unpleasant distracters), were most consistent with the AT-AL model.
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