Grouping of list items reflected in the timing of recall: implications for models of serial verbal memory

Three experiments examined the effect of temporal grouping on the timing of recall in verbal serial memory. Compared to an ungrouped condition, recall in a grouped condition produced a peak in latency between the groups (Experiment 1). However, the ratio of within- to between-group intervals at presentation was not reflected in recall (Experiment 2), contrary to the predictions of some oscillator models (Brown, Preece, & Hulme, 2000; Burgess & Hitch, 1999). In Experiment 3, grouped and ungrouped lists of different lengths were compared to assess a recent version of the ACT-R model applied to serial recall (Anderson, Bothell, Lebiere, & Matessa, 1998). Recall latencies showed a cost at group onset related to group size and a cost for all items of the first group associated with carriage of a second group. Results are discussed with reference to oscillator models, the ACT-R model, and augmented versions of it.