Abstract: As one of the most important skills in human’s daily life, face recognition can help us to promote social interactions and adapt to the environment. Previous ERP studies showed that face recognition could induce N170 (a negative potential peaking at about 170ms) over lateral occipito-temporal electrodes, some researchers argued that N170 might reflect the early structural encoding process. It is widely recognized that N170 possesses right hemisphere advantage, which suggests that the right hemisphere of brain is mainly responsible for structural encoding process. Searching for a specific face (the target) in the crowd and distinguishing it from other’s faces (distractors) are related to working memory which refers to the limited resource system for temporary storage and information processing. Since it is an important function of working memory to intentionally hold an item in mind for current use, the relevant research on working memory is more than 30 years. But the brain potential features of human face recognition during working memory as well as the brain responses to matching faces affected by prior learning remain unclear. Therefore, this article employs event-related potentials (ERPs) technology to explore the essence of face recognition N170 effect and the brain potential features of face recognition during working memory. The influence of prior learning on tracking and discrimination processes is also examined, which depends on the working memory status of a face. The delayed match-to-sample task paradigm was used in this study with pictures of faces as stimuli. 16 college students (eight male and eight female, Mean age = 20.31 years) participated in the experiment and performed sample target match tasks during working memory, tracking targets (familiar and new targets) and excluding the distractors (familiar and new distractors). The ERP results revealed that N170 was induced over lateral occipito-temporal electrodes when participants recognized the targets and distractors, and N170 amplitudes of targets and distractors at the same electrode had no significant differences. Whereas, there was a significant difference between P7 and P8 when different electrodes were compared with; Both the targets and distractors evoked a late positive ERP component peaking around 450ms (P300) during the working memory process. The ERPs of targets and distractors showed dissociation as early as 250ms when tracking new or studied targets respectively. The targets evoked larger and more positive ERPs than the distractors, and new targets evoked a more positive ERP waveform than the studied ones. The typical old/new effect was observed between ERPs of studied and new distractors about 250~650 ms in prefrontal area. The present study results suggest that face recognition N170 effect reflects the whole processing of perception, and there is a right hemisphere superiority of N170 — especially a right temporal region superiority; Moreover, our current findings demonstrated that prior learning affects brain responses to matching faces during a working memory task.

Key words: face recognition, working memory, target, distractor, ERP, N170