Beyond the unitary self: Behavioral and drift-diffusion modeling evidence for a true self-prioritization effect and intra-self competition.

While the self-prioritization effect (SPE) - the enhanced processing of self-relevant stimuli - is well established, current models typically treat the self as a monolithic entity, overlooking the cognitive dynamics between different self-representations. This study investigated whether the true self, conceptualized as the central core of identity, commands a distinct processing advantage. Across three experiments using a shape-label matching paradigm, we documented a robust true self-prioritization effect (TSPE). Crucially, we observed a pattern of competitive dynamics: while the general self showed prioritization when presented in isolation (Experiment 2), its processing advantage was abolished in the presence of the true self (Experiment 1), a finding shown to be distinct from conceptual ambiguity (Experiment 3). Computational analyses using the hierarchical drift diffusion model (HDDM) revealed that these effects were primarily driven by differences in the rate of evidence accumulation (drift rate). These findings are consistent with a hierarchical account, in which the self-concept is not cognitively flat but hierarchically organized, with the true self functioning as a salient contextual anchor that marginalizes peripheral self-aspects to optimize decision making.