Neural Correlates Of Supraliminal And Subliminal Rewards On Unconsciously Triggered Response Inhibition

Abundant literatures debating the effects of supraliminal and subliminal rewards always focused on the influence of rewards on conscious cognitive control. Moreover, recent studies suggested that unconscious stimulus could also trigger high-order cognitive control (e.g., unconscious inhibitory control). Sequential research has revealed that unconscious cognitive control had close relationship with conscious counterpart. Little research, however, investigated whether supraliminal and subliminal rewards can influence unconscious cognitive control. Thus, we develop three experiments to investigate the neural mechanisms of supraliminal and subliminal rewards on conscious and unconscious inhibitory control. In experiment 1, we attempted to confirm that the consciously triggered response inhibition exist in the modified Go/No-Go task including conscious and unconscious Go trials as well as the No-Go ones. Therefore, we replicated the study developed by van Gaal et al (2010). The results revealed that participants elicited longer reaction time for unconscious No-Go trials than for unconscious Go trials, suggesting that unconsciously triggered response inhibition existed really in modified Go/No-Go trials. In experiment 2, we designed an experiment combining the reward-priming paradigm with a modified Go/No-Go task which could induce both conscious and unconscious inhibitory control to address this issue. Participants in this study were firstly exposed to a high or low value coin presented supraliminally or subliminally, followed by a run of the modified Go/No-Go task. They were informed that they could earn the coin as reward if they responded correctly to each trial of the run. Results showed that participants attempted to achieve supraliminally presented high-value rewards would elicited larger amount of reaction time slowing (RT slowing) than low-value rewards, indicating that consciously perceived higher rewards would enhance individual’s unconscious triggered response inhibition. However, this facilitating reward effect was not observed when rewards were presented subliminally. In experiment 3, we investigated the neural mechanism underlying supraliminal and subliminal rewards on conscious and unconscious initiated response inhibition by using event related potentials (ERPs). Behavioral results showed that supraliminal rewards, rather than subliminal rewards, influenced unconscious inhibitory control, as reflected by larger amount of reaction time slowing (RT slowing). More importantly, ERP results showed that supraliminal high-value rewards (vs. low-value rewards) facilitated both of conscious and unconscious inhibitory control, as showed by greater centro-parietal P3 associated with better behavior performance. However, neither greater brain electrical activity nor better behavior performance was observed when rewards were presented subliminally. Together, these findings indicated dissociable neural mechanisms underlying supraliminal and subliminal rewards during conscious and unconscious Go/No-Go task. These findings expanded our understanding of the relationship between reward, consciousness and cognitive control.