EFFECTS OF VOCABULARY SIZE AND ACOUSTIC SIMILARITY ON SERIAL-RECALL OF MOUTHED STIMULI

The characteristics of mouthed recency and suffix effects found in imm ediate serial recall tasks with visually presented stimuli were examin ed. In past research enhanced recency with mouthing when stimuli were drawn from Size 8 but not Size 3 vocabularies was found (Turner et al. , 1987). One cause for these findings may have been differences in the acoustic similarity between items from the Size 3 and Size 8 vocabula ries. In the present experiment the degree of similarity was manipulat ed for vocabulary Sizes 3 and 8. The mouthed or passively read letters were acoustically similar, dissimilar, or mixed. The results replicat ed the vocabulary size effects found in Turner et al. but were not con founded by the acoustic similarity of the list items. Mouthed recency and suffix effects were found in recall of Size 8 but not Size 3 vocab ularies, and the vocabulary size effects were found regardless of acou stic similarity. Conversely, research has found auditory recency and s uffix effects to be dependent on the acoustic similarity of list items (e.g., Crowder, 1976; Greene & Crowder, 1984) and independent of voca bulary size (Turner et al., 1987). The findings thus lead to the concl usion that auditory and mouthed recency and suffix effects are not med iated by the same underlying source.