Abstract
The present study examined whether and how center surround suppression (CSS) effects in visual motion processing vary as a function of chronic stress and physiological arousal. Thirty-nine college students participated (18 females, 21 males) and completed a psychophysical motion task where they discriminated the direction of motion of a sinusoidal grating. CSS was quantified by taking the difference in accuracy between large (where the grating was 5 degrees of visual angle) and small (0.7 degrees) conditions. Performance on the task was compared to chronic stress (measured using a modified version of the Perceived Stress Questionnaire). The impact of arousal was explored using a within subjects design; subjects performed the motion discrimination task while aroused due to physical exercise, and while at baseline. Exercise-induced arousal did not have a significant effect on CSS or on baseline motion processing in the small condition. Chronic stress was positively correlated with CSS (p = .017) for the presentation time at which the effect peaked (66 msec), but not with baseline motion discrimination performance in the small condition. The results are consistent with the idea that CSS does not vary as a function of arousal, but rather as a function of stress and depressed mood (the latter as shown in prior studies).