Rewards Expected Impact Of Neurocognitive Mechanisms Of Facial Emotion Processing

It is widely reported that reward modulate "top-down" attention control, and bias attention to the stimuli which were related to high reward. Motivation improves performance of cognitive tasks, such as spatial attenttional orienting, visual search, and conflict control. Previous studies show the interaction between reward system and emotion system, such as increase in activity of ventral striatum have been found in response to positive affect induced by reward anticipation, and amydala’ activity was found in both processing of reward and emotion. More recently, the interaction between reward and emotion was found in memory formation We want to investigate the cognitive and neural mechanisms of the influence of reward expectation on the process of facial expressions.Three experiments was designed and conducted to explore the problem. All the participants were undergraduates or postgraduates came from Capital Normal University, and different subjects were participated in three experiments. In Experiment1, we adopted cue-target paradigm and ERPs technology. Central cue indexed the reward property of this trial, and participants were asked to discriminate the expressions of target faces (positive/neutral/negative). Behavioral results showed that RTs to emotional faces were generally faster than to neutral faces, and RTs on incentive trials were shorter than on non-incentive trials. Cue-elicited ERPs were modulated by monetary incentive, such that incentive cue elicited larger P1(130～200ms), P2(200～300ms)、P300(300-600ms) amplitude than the non-incentive cue. Target-elicited N300were modulated by reward anticipation and emotional valence. The reward-effect for N300was larger in negative condition than in positive and neutral conditions.Significant stimuli such as money, emotional faces would capture attention, and attentiaonal resources play an important role in the process of emotional information. In Experiment2a,2b, we used exogenous cue paradigm to investigate the role of spatial attention resource in the influence of reward on the processing of emotional facial expressions. Exogenous cue indicated the reward property of the trial, and participants’ task was to identify the expression of target faces (negative/neutral). In Experiment2a, the SOA between cue and target was200～300ms, valid cues promote the process of target in cued place and reward anticipation enhanced participants’ performance. Most important was that, an interaction between reward anticipation and emotional valence was found in valid condition-larger reward-effect was found in negative condition compare to neutral condition, but not in invalid condition. In Experiment2b, the SOA between cue and target was950～1250ms, the response to the target in cued position was slower than in uncued position. And the interaction between reward anticipation and emotional valence was found in both valid condition and invalid condition, that was larger reward-effect in negative condition than in neutral condition.These results indicates that motivation promote the performance of participants. The influence of reward anticipation on emotion was emerged in the late stage of processing. We consider that sufficient process is necessary to come up with an interaction between reward and emotion. And enough attentional resources is essential for sufficient processing. We conclude that the influence of reward expectation on emotion processing was emerged in the condition of enough attentional resources.