Aims: 

Recent investigations about trustworthiness propose the existence of a specialized brain module, which may serve the evolutionary adaptive cognitive mechanism to recognize cheaters. Our aim was to investigate event related potential (ERP) correlates of automatic recognition of trustworthiness as a facial trait.

Methods: 

Thirty six healthy volunteers evaluated standardized trustworthy and untrustworthy computer-generated facial images on the cheater/cooperator dimension. Another group of subjects (n=34) were recruited for a passive odd ball ERP experiment, where photos of putative cheaters or cooperators were briefly presented on a computer screen, in a visual Mismatch Negativity (vMMN) paradigm (with 9:1 standard/deviant ratio). The subjects' task was to respond to a central cross-flip (in 10% of the inter trial intervals) with a button press, while ERPs and reaction time (RT) data were recorded.

Results: 

Untrustworthy images were consequently rated as cheaters and trustworthy ones as cooperators (r²=0.73, P<0.05). Deviant minus standard potential waves (vMMN) were found bilaterally in occipital regions (O1, O2).

Conclusion: 

The present results indicate that the visual system automatically registers the difference between putative cheater and cooperator faces at an early processing stage. This may serve as the neural basis of later decisions regarding cheating or cooperation social exchange situations.