Serial Position and Set Size in Short-Term Memory: The Time Course of Recognition

Subjects viewed sequentially presented lists of 3-6 words, which were followed by a recognition probe. Memory retrieval speed (dynamics) and strength were measured in an interruption speed-accuracy trade-off (SAT) procedure and a collateral reaction time (RT) procedure. In SAT, item strengths depended on serial position, but only two retrieval speeds were observed: a fast rate for the last item in the study list (a case of immediate repetition between study and test) and a slow rate for all other items that was independent of serial position and set size. Serial-position-dependent strengths and set-size-dependent criterion shifts accounted for standard RT patterns that have been taken as evidence for serial scanning in short-term memory.