Reward expectation regulates brain responses to task-relevant and task-irrelevant emotional words: ERP evidence

Abstract

We investigated the effect of reward expectation on the processing of emotional words in two experiments using event-related potentials (ERPs). A cue indicating the reward condition of each trial (incentive vs non-incentive) was followed by the presentation of a negative or neutral word, the target. Participants were asked to discriminate the emotional content of the target word in Experiment 1 and to discriminate the color of the target word in Experiment 2, rendering the emotionality of the target word task-relevant in Experiment 1, but task-irrelevant in Experiment 2. The negative bias effect, in terms of the amplitude difference between ERPs for negative and neutral targets, was modulated by the task-set. In Experiment 1, P31 and early posterior negativity revealed a larger negative bias effect in the incentive condition than that in the non-incentive condition. However, in Experiment 2, P31 revealed a diminished negative bias effect in the incentive condition compared with that in the non-incentive condition. These results indicate that reward expectation improves top-down attentional concentration to task-relevant information, with enhanced sensitivity to the emotional content of target words when emotionality is task-relevant, but with reduced differential brain responses to emotional words when their content is task-irrelevant.

Differential modulations of reward expectation on implicit facial emotion processing: ERP evidence

“…There is no consensus, though, as to whether the EPN reflects automatic attentional orientation toward emotional stimuli (Kissler, Herbert, Winkler, & Junghöfer, ; Schacht & Sommer, ) or whether it is sensitive to emotional content only when sufficient attention is allocated to the stimuli (Bayer, Sommer, & Schacht, ; Frühholz et al, ). In our recent study (Wei et al, , experiment 1), the EPN exhibited a larger difference between negative and neutral words in the incentive (vs. the nonincentive) condition in an explicit emotional (word) categorization task, demonstrating an interaction between reward expectation and emotion at an early processing stage. However, to our knowledge, there are no studies in the literature that reported a modulatory effect of reward on the EPN in implicit emotional tasks.…”

“…They found that the emotion‐related and reward‐related effects were independent from each other. In contrast, using a similar design but asking participants to judge the color of negative and neutral words, Wei et al (, experiment 2) observed reduced differential amplitudes between negative and neutral words in the P3a time window (300–380 ms poststimulus onset) in the incentive, as compared to the nonincentive, condition, thus demonstrating an interactive effect between incentive motivation and implicit emotional processing. In a recent neuroimaging study, Padmala et al () instructed participants to identify the orientation of peripheral bars while ignoring a centrally presented negative or neutral picture.…”

“…As background to the aforementioned effects of reward expectation and emotional processing on attention and executive control, recently several studies have attempted to directly examine the relationship between reward expectation and explicit and/or implicit emotional processing (Kaltwasser, Ries, Sommer, Knight, & Willems, ; Padmala & Pessoa, ; Padmala, Sirbu, & Pessoa, ; Wei & Kang, ; Wei, Wang, & Ji, ). When participants were instructed to discriminate the emotional valence of emotional stimuli (i.e., explicit emotional processing) following incentive or nonincentive cues, behavioral and electrophysiological evidence revealed that reward expectation in the incentive (vs. the nonincentive) condition amplifies emotional effects—that is, the preferential processing of negative and positive emotional stimuli versus neutral stimuli (Kang, Zhou, & Wei, ; Wei & Kang, ; Wei et al, ; Wei, Kang, Ding, & Guo, ).…”

“…In summary, the present study was predicated on the assumption that task set determines how deeply emotional content is processed (Frühholz et al, ; Rellecke et al, ; Wei et al, ; see Eimer & Holmes, , for a review). Accordingly, we expected that emotional (vs. neutral) facial expressions would engender stronger brain responses, in a large number of the aforementioned ERP components, when the faces were targets (as in Experiment 1), rather than distractors (as in Experiment 2), even though the emotionality of the faces was irrelevant in both cases.…”

Motivation enhances control of positive and negative emotional distractions

“…Negative images slowed response times (RTs) relative to neutral images; but on reward trials, this slowing was 4 eliminated. Further support comes from an event-related-potential study (Wei, Wang, & Ji, 2016) in which participants responded to the colour of negative and neutral words. The emotional modulation of the P3 component was eliminated on cued-incentive trials.…”