An approach to investigating individual differences in the cognition of situations is presented. Situations are characterized in terms of Gibson's notion of affordances, and it is suggested that individuals differ in the extent to which they differentially process information specifying certain types of affordances rather than others. This differential cognitive processing of a situational affordance is termed a "processing bias." It is proposed that processing biases are manifest in an individual's anticipation, perception, and memory of situations. To illustrate the approach, a processing bias for social vs. nonsocial affordances is investigated within and among these three cognitive domains. The relationship of this processing bias to two facets of the personality trait dimension of sociability--overall level and self-schemata--is also examined. Such research on processing biases may help to clarify the role of cognition in person-situation interactions. The greatest strength of the approach is that its characterization of individual differences in cognition and behavior is complementary to a general approach to describing human environments.