Adding and Averaging Effects in Impression Formation as a Function of the Situational Context

Male and female Ss made comparative judgments of paired sets of simultaneously presented income stimuli. The pairs were constructed so that the sum of the values was higher in one set than in the other, while the mean income was simultaneously higher in the latter set than in the former. When the incomes within a set were represented as all belonging to the same person or when the incomes were attributed to different members of a family, both men and women tended to rate higher in economic status whichever sets of stimuli had the higher sums in direct relation to the manipulated discrepancy between sums. When the same stimuli were attributed to different members of a group, both sexes rated higher in economic status whichever sets had the higher arithmetic mean values in direct relation to the manipulated discrepancy between arithmetic means. The significance of this finding is in demonstrating that the stimulus-combination rule in impression formation is at least partially predicated upon situational determinants and that neither simple summation nor simple averaging is an exclusively valid or invalid combinatory principle.