Super-capacity me! Super-capacity and violations of race independence for self- but not for reward-associated stimuli

Participants are biased in responding to stimuli associated with themselves compared with stimuli related to other people. This self-bias may reflect the reward value of self-related stimuli (Sui, He, & Humphreys, 2012). In this article, we examined the identification of self- and reward-associated stimuli under conditions in which either single or redundant stimuli were presented. The redundant stimuli could be the same shape or they could be different shapes both associated with either the self or a friend or high or low reward. We formally tested whether the redundant stimuli violated the independent race model for the identification of multiple stimuli (Miller, 1982) and whether the redundant stimuli were processed with super- or limited-capacity (Townsend & Eidels, 2011). We found that redundant self stimuli alone both violated the independent race model and were processed with super-capacity. In contrast, the redundant high reward stimuli did not show race inequality and were associated with limited capacity processing. The data advance our theoretical understanding of self bias both by demonstrating that it can be distinguished from effects of reward, and by suggesting that self-bias can result from the enhanced integration of stimuli associated with the self. The implications for understanding self bias effects are discussed