People have the power: priority of socially relevant stimuli in a change detection task

Change detection performance is influenced by a number of factors, among which is the informativeness of targets. It has not been clarified, yet, whether the highly informative regions have a processing priority as a result of resource deployment from other tasks or whether it results from a better resource management. In this paper, we adopted a change detection paradigm in which thirty participants were randomly assigned to two groups: single (change detection task) and dual task [change detection and a simplified version of the Paced Auditory Serial Oppository Task (PASOT, Gow and Deary in J Clin Exp Neuropsychol 26:723–736, 2004), which implies a verbal effort]. Stimulus informativeness was defined as social relevance, that is, changing targets were people (high relevance) versus objects (low relevance), all other aspects (i.e., salience and position in the scene) kept constant. As hypothesized, data analyses showed a significant main effect of social relevance and task condition, i.e., better change detection performance and lower change detection times for people versus objects and for single than for dual task condition. Interestingly, the PASOT accuracy remained stable across the person versus object trials, thus implying that the better performance with socially relevant targets could not be explained by a resources withdrawal from the secondary task.