Effects of Word Processing and Short‐term Memory Deficits on Verbal Learning: Evidence from Aphasia

Abstract

We report two experiments that investigate the abilities of aphasic subjects with lexical and short‐term memory impairments to learn supraspan lists of 10 words. We examined effects of stimulus factors (characteristics of words and lists to be learned) and subject factors (verbal and nonverbal STM span, nature of language impairment). Learning ability was influenced by the imageability and frequency of the words to be learned (Experiment 1) and by the linguistic relationship among words in a list (Experiment 2). Additionally, learning ability was affected by the nature of a subject's word processing deficit (whether it involved semantic and/or phonological processes). Phonological ability was positively associated with learning in both experiments, and semantic ability was associated with learning when words in a list were high in both frequency and imageability (Experiment 1) or were contextually related to one another (Experiment 2). Finally, verbal STM span was positively related to learning performance, but the effect was more pronounced for word span than digit span. These relationships among word processing ability, verbal STM span, and learning ability are discussed with reference to learning in aphasia and to models of learning more generally.