Abstract:  Previous studies have shown that outcome evaluation is sensitive to social influences. However, it remains unknown whether the consistency of choice between self and others also affect the outcome evaluation. To gain more insight in this research area, we designed two experiments in the present study, in which two participants (a real participant and a confederate) completed a gambling task together. In this task, the real participant chose from two options before/after the confederate made his/her choice. The outcomes of their choices revealed after both of their choices were made. According to the choosing scenario, 2 conditions were considered in the present study for both taking the same (consistent choices) or different options (inconsistent choices). Sixteen (7 males, 20.40 ± 1.11 y) and twenty (10 males, 22.21 ± 1.70 y) healthy adults participated in the experiment 1 and 2, respectively. With normal or corrected to normal vision, none of them reported any history of neurological diseases or brain injuries. Participants were asked to perform a gambling task in collaboration with another participant. By taking turns to choose one from two covered cards, they won 50 or 0 RMB depending on their choosing consistency. In the experiment 1, the confederate chose first while in the experiment 2 the real participant chose first. After both of them made their choices and were informed with the other’s choice, the outcome were revealed, which fell in 4 categories of (i) both chose the same card and both won; (ii) both chose the same option and both lost; (iii) they chose different cards and the real participant won; and (iv) they chose different cards and the real participant lost. ERP results showed that in the early stage of outcome evaluation, no matter who chose first, a more pronounced dFRN was associated with participants taking the same option than taking different options. In the later stage of outcome evaluation, only in experiment 2, increased P3 and LPP were observed when their choices were the same than different. Our data suggests that the consistency of choices between self and other does modulate the neural activity of outcome evaluation. Specifically, in the early stage, consistent choices amplified the neural response to negative outcome as indicated by the enlarged dFRN. In the later stage, when the participant made the choice first and saw the other chose a different option, this inconsistency would trigger a sense of conflict, leading to more mental processes to avoid it later. This effect reflected in the enlarged amplitudes of P3 and LPP. Our finding provides some insights into how social context influences the psychophysiological processes of outcome evaluation.

Key words:  outcome evaluation, consistency of choice, ERPs, FRN, P3, LPP