Threat and anxiety affect visual contrast perception

Threat cues activate the visual cortex and are detected faster than neutral cues as evidenced by functional brain imaging during viewing of visual threat and neutral stimuli. The functional visual processes underlying these phenomena have not been determined. Pattern visual evoked potentials were elicited in a baseline and a verbal threat condition with two stimulus contrasts in subjects with high and low trait anxiety. Threat reduced the latency of the early P100 wave in the low but not the high anxious group. The reduction was greater with increasing stimulus contrasts. The dependence of the P100 latency on trait anxiety is reminiscent of the Yerkes-Dodson inverted U-shape curve, which relates anxiety to behavioural responses. These results show that threat affects perceptual processes and suggest that data based on the effects of threat in visual search studies should be reappraised to include acceleration of contrast perception.