The Effects of Prior Beliefs and Stimulus Prevalence on Self-Other Prioritization

Although self-relevance is widely acknowledged to enhance stimulus processing, the exclusivity of this effect remains open to question. In particular, in commonly adopted experimental paradigms, the prioritization of self-relevant (vs. other-relevant) material may reflect the operation of a taskspecific strategy rather than an obligatory facet of social-cognitive functioning. By changing basic aspects of the decisional context, it may therefore be possible to generate stimulus-prioritization effects for targets other than the self. Based on the demonstration that ownership facilitates object categorization (i.e., self-ownership effect), here we showed that stimulus prioritization is sensitive to prior expectations about the prevalence of forthcoming objects (owned-by-self vs. owned-byfriend) and whether these beliefs are supported during the task. Under conditions of stimulus uncertainty (i.e., no prior beliefs), replicating previous research, objects were classified more rapidly when owned-by-self compared to owned-by-friend (Expt. 1). When, however, the frequency of stimulus presentation either confirmed (Expt. 2) or disconfirmed (Expt. 3) prior expectations, stimulus prioritization was observed for the most prevalent objects regardless of their owner. A hierarchical drift diffusion model (HDDM) analysis further revealed that decisional bias was underpinned by differences in the evidential requirements of response generation. These findings underscore the flexibility of ownership effects (i.e., stimulus prioritization) during object processing.