Cooperation　and　competition　in　social　interaction　are　important　to　social　development.　There　are　many　studies　examining　the　neural　mechanism　underlying　these　behaviors;　however,　little　is　known　about　the　potential　role　of　payoff　norms　in　social　interactions.　This　study　introduced　two　distinct　payoff　norms:　zero-sum　(ZS)　and　non-zerosum　(NZS).　In　the　ZS　group,　only　the　player　with　the　highest　total　score　would　receive　a　reward;　while　in　the　NZS　group,　rewards　were　determined　by　the　combined　total　score　of　both　players,　and　individual　rewards　were　prorated　according　to　each　player＇s　contribution　to　the　total　score.　Electroencephalography　was　used　to　examine　individuals＇　neural　responses　during　the　Chicken　Game　in　these　different　groups.　The　behavioral　findings　revealed　a　higher　rate　of　cooperation　in　the　NZS　group　compared　to　the　ZS　group.　Aggressive　behaviors　from　opponents　elicited　larger　feedback-related　negativity　(FRN)　and　lower　P300　amplitudes　in　both　groups.　Notably,　larger　FRN　and　smaller　P300　amplitudes　were　elicited　by　participants＇　aggressive　behaviors　compared　to　their　cooperative　behaviors　in　the　ZS　group,　whereas　larger　P300　amplitudes　were　elicited　by　aggressive　behaviors　compared　to　cooperative　behaviors　in　the　NZS　group.　Additionally,　a　greater　theta　event-related　synchronization　(ERS)　was　observed　solely　when　participants　exhibited　aggression　in　the　NZS　group.　The　type　of　group　moderated　the　association　between　posterior　theta-ERS　and　cooperative　rates.　Specifically,　theta-ERS　was　negatively　associated　with　cooperative　rates　in　the　NZS　group,　whereas　a　reversed　association　was　found　in　the　ZS　group.　These　findings　provide　valuable　insights　into　the　neurobiological　foundations　of　cooperation　under　different　economic　payoff　norms.