Abstract The self-prioritization effect refers to the tendency for individuals to perceive self-related stimuli more accurately than other-related stimuli. We leveraged this phenomenon to investigate the mechanisms underlying empathy. According to the self–other merging hypothesis, empathy broadens self-representation to encompass others, predicting a reduced self-prioritization effect. In contrast, the self–other distinction hypothesis posits that empathy heightens the differentiation between self and other, predicting an increased self-prioritization effect. To test these competing hypotheses, we employed a perceptual task combined with electroencephalogram (EEG) recordings, and analyzed the data by using signal detection theory. Fifty-two participants aged 19 to 33 years were randomly assigned to either a high-empathy or low-empathy group. Participants listened to an interview and were instructed to either empathize with or remain neutral toward the interviewee. Subsequently, they completed a shape–label matching task using geometrical shapes associated with the self, the interviewer, and the interviewee. The self-prioritization effect was measured by performance differences between self-related and other-related stimuli. Different performance indices provided support for each hypothesis. Specifically, the patterns observed in the sensitivity index ( d’ ) and the lateral positive component (LPC) of the event-related potential supported the self–other distinction hypothesis at the perceptual and attentional levels. In contrast, the patterns in the response bias index (c) and reaction time supported the self–other merging hypothesis at the response level. These findings suggest that empathy influences self-representation in distinct ways across different levels of processing.
Lo et al. (2026) studied this question.