Ownership and agency modulate self-positivity effect: Behavioral and neural evidence.

In value assessment, the self-positivity effect refers to the tendency to assign higher value to self-related objects. However, the distinct and interactive contributions of ownership and agency to this effect remain unclear. Across four behavioral studies (total N = 137) and an event-related potentials (ERP) study (N = 30), we manipulated ownership and agency using an object evaluation paradigm while recording subjective value ratings and P300 amplitudes. Results showed that ownership enhanced valuation, whereas agency influenced valuation only when the object was already self-owned, with the direction of both effects modulated by valence. The combination of self-ownership and self-agency elicited enhanced P300 amplitudes, reflecting prioritized processing of self-relevant information at early neural stages-a pattern present in gain contexts but absent in loss contexts. These findings clarify the distinct roles of ownership and agency in shaping the self-positivity effect in value assessment, with implications for understanding consumer behavior and risk decision-making.