| Emotion acts as a kind of special information not only playing an irreplaceable role in enriching the experience during daily lives of human beings, in the meanwhile, it brings more significant influences on our work, studies and lives relative to other events. The evidences from empirical studies showed that emotional stimuli can preferentially capture attention so as to be processed rapidly, reflecting the processing priority of emotion. It therefore speculates that larger interference could be observed during the presentation of negative distracters compared with positive, or neutral distracters.The interference of emotional distracters on the central task can be essentially divided into two aspects. One interference effect emerges from emotion to the pure cognitive task, which actually reflects the ability of emotional distracters to attract attention. The other interference effect stems from the inconsistency of emotional valence between the goal-relevant stimulus and the goal-irrelevant stimulus, which is emotional conflict. In consistent with the former interference, this kind of interference is on the one side driven by the occupation of attentional resources at the early processing phase, while it reflects cognitive control that is initiated by the occurrence of conflict to resolve conflict. A large number of studies showed that the interference of emotional distracters on cognitive task is modulated by perceptual load, this finding indicated that despite the processing priority of emotional stimuli, their processing is still subject to top-down attentional control. However, the issue about whether the modulation of perceptual load on emotional interference still remains when central task is related to emotional, which has not been investigated. As such, previous studies regarding emotion did not distinguish negative emotion and positive emotion; however, the fact is that these two emotions(positive, negative) showed significant differences in behavioural performance, as well as specific influences on other cognitive processes, such as perceptual load and cognitive control. Specifically, negative emotion has stronger ability to capture attention during the perceptual phase. In addition, negative emotion can reduce cognitive conflict through improving cognitive control. It is thus conceivable to assume that emotional conflict differs, which is elicited between negative and positive stimuli, given that cognitive control is different during these two conditions. In light of the two issues, this study initially investigates whether emotional conflict elicited by positive or negative faces is modulated by the perceptual load. Further experiments are performed to explore the difference of the conflict effect, particularly in the low perceptual, as well as their underlying neural mechanism.To study this issue, Experiment 1 aimed to investigate the influence of perceptual load on emotional conflict using the combination paradigm of perceptual load and emotional face-word Stroop. The results showed that even though perceptual load modulated conflict effect differently between the negative face and the positive face, this modulatory effect was not reflected in selective attention at the early processing phase. Instead, the modulation of perceptual load actually affected cognitive control implementing at relatively late processing phase, which was involved in resolving conflict and resulted in different conflict patterns between positive faces and negative faces. It was therefore suggested that the influence of perceptual load on emotional conflict not only determined how many resources can be devoted to processing distracting faces, in the meanwhile, the implement of cognitive control that is accompanied by conflict occurrence also depended on available resources.Based on the Experiment 1, we analyzed the distinct influence of perceptual load on emotional conflict elicited by positive faces and negative faces. And then, Experiment 2 and Experiment 3 used behavioural technique and f MRI technique respectively to further explore the difference of conflict effect between negative faces and positive faces by using typical face-word emotional Stroop paradigm. Experiment 2 showed that emotional conflict was absent in the negative face condition, whereas it was significant in the positive face condition. Experiment 3 duplicated results showing in Experiment 2 at the behavioural level. What’s more, neuroimaging results showed similar patterns regarding conflict effect for negative faces and positive faces specifically in areas associated with emotional face processing. More importantly, DLPFC showed distinct coupling patterns between target areas between negative faces and positive faces. In the negative face condition, DLPFC negatively coupled with emotional face processing network including FFA, MTG, MOG, AI), whereas DLPFC negatively coupled with default mode network(DMN)(IPL, PCC, precuneus) in the positive face condition.To conclude, the three experiments initially indicated that perceptual load modulated conflict effect showing between negative faces and positive faces in a different way. It is notable that this modulatory effect was not reflected in selective attention occurring at the early stage, instead, perceptual load affected cognitive control that was involved in emotional conflict resolution and was modulated by emotional faces, as a result, conflict effects driven by negative and positive faces showed distinct patterns between high and low perceptual loads. Specifically, emotional conflict is controlled better for negative faces compared with positive faces, possibly because processing priority of negative faces rapidly trigger conflict control through subcortical pathway, which in turn efficiently resolves conflict through timely blocking the resources devoted to processing negative faces. |
