The Functional Determinants of Short-Term Memory

A functional, perceptual-motor, account of serial short-term memory is examined by investigating the way in which an irrelevant spoken sequence interferes with verbal serial recall. Even with visual list-presentation, verbal serial recall is particularly susceptible to disruption by irrelevant spoken stimuli that have the same identity as—but which are order-incongruent with— the to-be-remembered items. We test the view that such interference is due to the obligatory perceptual organization of the spoken stimuli yielding a sequence that competes with a subvocal motor-plan assembled to support the reproduction of the to-be-remembered list. In support of this view, the interference can be eliminated without changing either the identities or objective serial order of the spoken stimuli but merely by promoting a subjective perceptual organization that strips them of their order-incongruent relation to the to-be-remembered list (Experiment 1). The interference is also eliminated if subvocal motor sequence-planning is impeded via articulatory suppression (Experiment 2). The results are in line with the view that performancelimits in verbal serial short-term memory are due to having to exploit perceptual and motor processes for purposes for which they did not evolve, not the inherently limited capacity of structures or mechanisms dedicated to storage.