Retrieval processes for serial order information.

Three experiments sought to specify how list structure and rehearsal pattern influence the retrieval of well-learned serial order information. Subjects learned a serial list of 12 words followed by a probed recall task measuring response time. Adjacent list items served as retrieval cues to permit probing of an item by cues which maintained or crossed semantic or rehearsal boundaries. Evidence for structure in serial recall was inferred from the large cue format effects on response time. Such effects were found to be consistent with the semantic relationships in categorized lists and the acquisition rehearsal pattern in unrelated lists. When rehearsal grouping and semantic relatedness were in conflict. the cue format effects conformed mainly to the rehearsal pattern. Extended practice over five sessions did not eliminate these effects for many of the serial items. These results suggest that the structure of the serial list. whether based on previous associations or present rehearsal patterns. can provide a basis for retrieval. A hierarchical search model based on item and order information provided good fits of the data. The model suggested that response time varies with cue formats because cues differ in their efficiency at directing search to the correct response in the list structure. The structure. which is acquired at the time of learning. determines cue efficiency and. hence. the subsequent effects upon response time.