The effect of interstimulus interval on sequential effects in absolute identification

摘要

In absolute identification experiments, the participant is asked to identify stimuli drawn from a smallset of items which differ on a single physical dimension (e.g., 10 tones which vary in frequency).Responses in these tasks show a striking pattern of sequential dependencies: The current responseassimilates towards the immediately preceding stimulus but contrasts with the stimuli further backin the sequence. This pattern has been variously interpreted as resulting from confusion of items inmemory, shifts in response criteria, or the action of selective attention, and these interpretationshave been incorporated into competing formal models of absolute identification performance. Intwo experiments, we demonstrate that lengthening the time between trials increases contrast toboth the previous stimulus and the stimulus two trials back. This surprising pattern of results isdifficult to reconcile with the idea that sequential dependencies result from memory confusion orfrom criterion shifts, but is consistent with an account that emphasizes selective attention.