Observation: Inter-Response Times in Serial . . .

We conducted a large scale study of inter-response times in serial learning, with and without intraserial repetition. Through repeated study and test trials, subjects learned random lists of consonants. Lists varied along a number of dimensions: list length, the presence/absence of a repeated element, the separation between repeated elements, and the position of the first repeated element. After attaining a criterion of three perfect forward recalls of a given list, we asked subjects to recall that list backwards. We examined both first trial accuracy and perfect trial interresponse times (IRT) for lists with and without repeated elements. For all lists, IRTs vary systematically with output position in a pattern of varying fast and slow responses suggestive of a grouping mechanism. Repetitions had a dramatic effect on IRTs. For massed repetitions, or repetitions at short lags, IRTs between the repeated elements were very fast (when compared with IRTs from identical positions in non-rep..