Abstract
Although an influence of value on perception and attention is largely undisputed, the exact nature of the interaction between valuation, perception and attention is open. To probe effects of value on perception and their interaction with attention, we used binocular rivalry induced by gratings of different color drifting in opposing directions. To ensure that observers' perceptual experience was veridically measured, their optokinetic nystagmus was used as indicator of the currently dominant percept. One percept was rewarded or asked to be attended and the amount of reward was signaled by the width of a blue annulus surrounding both rivaling gratings. We found that dominance increased for the rewarded percept relative to the other, non-rewarded, percept. Since the effect of reward was similar to attending the respective stimulus, we next tested whether our results were effects of value per se, or merely mediated by a shift in attention to the rewarded grating. Observers were asked to perform an attentionally demanding task either on the rewarded stimulus, the other stimulus or both: participants detected changes in the duty-cycle of the respective grating, which were sufficiently subtle to not by itself cause a switch in dominance. We found that reward still modulated perception even if attention was held constant. This renders it unlikely that effects of reward are mediated solely by attention. To test whether attention can nonetheless selectively enhance perception according to value, we performed the same experiment with the same visual stimulus signaling penalty instead of reward. We found increased dominance durations for the non-penalized percept, which were similar to the effects of reward. Taken together, our data show that more valuable stimuli are selectively enhanced, but that value has a direct impact on perceptual representations even if stimuli and attention directed to them are held constant.
Meeting abstract presented at VSS 2014