The articulatory determinants of verbal sequence learning

Two experiments (N = 154 in total) using the Hebb repetition effect—the enhancement of serial recall performance for a repeated sequence in amongst otherwise non-repeated sequences—reveal a key role for active articulatory-planning processes in verbal sequence learning, contrary to a prominent, phonological-store based, model (Burgess & Hitch, 2006). First, Hebb sequence learning was attenuated when articulatory planning of the to-be-remembered sequence was restricted by articulatory suppression. This was less the case with auditory sequences, however, suggesting that passive perceptual organization processes operating independently of articulation also contribute to the learning of sequences presented auditorily. Second, sequence learning was enhanced for phonologically similar compared to dissimilar items when that learning was particularly reliant on articulatory planning (i.e., with visual sequences). That this enhanced learning was eliminated when articulatory planning was restricted also points to an articulatory basis for this ‘phonological’ similarity effect. Third, an inconsistent temporal grouping of items across instances of the repeating sequence also abolished learning but only when that grouping—based on independent evidence from output response-times during serial recall—was instantiated within an articulatory plan. These results are the first to suggest that verbal sequence learning, and not only verbal serial short-term memory performance, may be explicable by recourse to general-purpose articulatory and perceptual processes.