Equivalent effects of grouping by time, voice, and location on response timing in verbal serial memory

The grouping of list items is known to improve serial memory accuracy and constrain the nature of temporal errors. A recent study (M. T. Maybery, F. B. R. Parmentier, & D. M. Jones, 2002) showed that grouping results in a temporal organization of the participants' responses that mimics the list structure but not the timing of its presentation. Here the authors tested the prediction that the temporal grouping of responses should yield the same pattern of response time (RT) irrespective of the method of grouping at presentation. Comparing temporal, location, and voice grouping, the results show that although these methods impact on recall accuracy to varying degrees, all 3 conditions produce significant and equivalent peaks in RT at the first position of each group. The RT data were accurately simulated through a model based on ACT-R's (J. R. Anderson & M. Matessa, 1997) basic principles. Altogether, the data suggest that the temporal organization of responses in verbal serial recall results from (a) declarative knowledge about the list's structure that is independent of the perceptual means by which grouping is induced at presentation and (b) the level of activation of the items per se.