Dissociating biases towards the self and positive emotion.

We examined whether self-biases in perceptual matching reflect the positive valence of self-related stimuli. Participants associated geometric shapes with either personal labels (e.g., you, friend, stranger) or faces with different emotional expressions (e.g., happy, neutral, sad). They then judged whether shape-label or shape-face pairs were as originally shown or re-paired. Match times were faster to self-associated stimuli and to stimuli associated with the most positive valence. In addition, both the self-bias and the positive emotion bias were reliable across individuals in different test sessions. In contrast there was no sign of a correlation between the self-bias and the emotion-bias effects. We argue that self-bias and the bias to stimuli linked to positive emotion are separate and may reflect different underlying processes.