Evidence for implicit scaling in comparative judgment

In two experiments, we examined the effects of manipulating the density of stimuli on comparison difficulty in a comparative judgment task. In Experiment 1, subjects was slower at judging the relative size of a pair when the members were adjacent items in the linear order than when the members were separated by items of intervening magnitudes. In Experiment 2, the advantage of choosing the larger rather than the smaller of two large stimuli (e.g., the congruity effect) increased when the linear order included many small items. In contrast, the advantage of choosing the smaller of two small items increased when the linear order included many large items. The applicability of the range-frequency theory (Parducci, 1965) to these results is discussed.