Electrophysiological indexes of ingroup bias in a group Stroop task: Evidence from an event-related potential study.

Although cognitive system assigns higher attentional resources to ingroup information than outgroup information, but it is unclear whether the ingroup bias can be measured by the processes that are related to allocation of attentional resources to ingroup information. Thus, a group Stroop task was developed to study the issues combining with event-related potential (ERP) technique in this study. Specifically, 34 subjects (17 female, mean age = 20.76 ±â€¯1.26) were firstly divided into blue or red group (17 subjects for each group); then they were asked to categorize four words of Stroop task into "our team" or "other team" based on the ink color (blue/red) of the words whose meaning were also red/blue. The behavioral results showed that outgroup ink color processing was interfered by ingroup word meaning, but the ingroup ink color processing was less/not interfered by outgroup word meaning. The ERP results showed that the amplitude of frontal N100 was enhanced when more attentional resources were automatically captured by ingroup information in early stage than outgroup information; P2/N2 amplitude was reduced or enhanced when outgroup information processing was interfered by ingroup information; enhanced P3b amplitude reflected that attention could be more easily allocated to ingroup information than outgroup information based on target. This study implied a novel direction to study the neural basis of ingroup bias by investigating the roles of ingroup bias in assigning attentional resources to group information.

Self-reference processing of fat-face and sick-face in individuals with different disgust sensitivity: Evidence from behavioral and neuroelectrophysiology.

Self-reference effect has been widely discussed. Previous scholars believed that self-related information can be processed faster is due to the positive attribute of self-concept which speeds up self-related information processing. When self-related information is given negative attributes, the self-reference effect will be weakened. In this study, fat and sick, two kinds of stimuli associated with disgust characteristics, were added to self- and other-faces. We found that disease stimuli, which are closely related to survival threats, eliminated the self-reference effect while the obesity stimuli only weakened the self-reference effect to a certain extent. Event-related potential (ERP) analysis demonstrated that sick-faces have a greater amplitude than standard-faces in the EPN and LPP components. We believe that this may be due to the urgency of the disease threat, which leads to the selective attention to the disease threat in the early perception stage and the allocation of more attention resources for rapid response in the later stage. In addition, we found that disgust sensitivity specifically maintains individuals' self-referential effects by dissociating individuals from others in disease contexts. These results further support the behavioral immune function of disgust as a gatekeeper of the self in potentially contaminated environments. In conclusion, our study showed that in the face of survival threat, the self-reference effect is eliminated, and disgust tried to slow down this elimination effect to protect self. This study extends the behavioral immunity theory to some extent and further deepens the understanding of the relationship between disgust and self.