Why Is Word Learning Related to List Memory? Empirical and Neuropsychological Tests of a Computational Account

Why Is Word Learning Related to List Memory? Empirical and Neuropsychological Tests of a Computational Account Prahlad Gupta (prahlad-gupta@uiowa.edu) Department of Psychology; University of Iowa Iowa City, IA 52242 USA Introduction Neuropsychological Investigation The revised version of our model incorporates the view that there is a functional relationship between the abilities, all of which invoke the same sequenc- ing mechanisms. If this is really the case, we would expect relationships between these abilities to ob- tain even following early neurological injury across a variety of lesion sites. This is because in the case of early lesions, there is a real possibility for remis- sion of deﬁcits as a result of neural reorganization; persistence of correlations would thus support the hypothesis of an underlying functional relationship. We examined this question by administering tests of word learning, nonword repetition, and ISR to 5-10 year old children who had suﬀered perinatal brain injury across a variety of sites, and to age-matched controls (Gupta et al., 2003). The results indicate that the relationships between ISR, nonword repe- tition, and word learning are exhibited even under conditions of early brain injury. These ﬁndings thus provide further support for the functional architec- ture of our revised model. These various lines of evidence together clarify how common sequencing mechanisms may underlie both nonword processing and immediate list recall, thereby oﬀering an explanation of why word learning is related to list memory. A growing body of evidence indicates that human word learning, nonword repetition, and immediate serial recall (ISR) abilities are related in some way (e.g., Baddeley et al., 1998). It seems clear why word learning might be related to nonword repetition: ev- ery known word was once a nonword to a particular learner, so greater facility in processing nonwords should lead to greater facility in eventually learning them. But why might nonword repetition and list recall be related? Nonwords as Lists One possibility is that a nonword is processed like a list when ﬁrst encountered, and is thus directly de- pendent on list sequencing mechanisms. If this were the case, we would expect to observe serial position eﬀects in repetition of the sequence of sounds com- prising nonwords, just as in ISR of lists of words. We conducted three experiments to examine sylla- ble serial position eﬀects in repetition of individual polysyllablic nonwords, and obtained signiﬁcant pri- macy and recency in all three experiments (Gupta, Testing Alternate Models References Baddeley, A. D., Gathercole, S. E., and Papagno, C. (1998). The phonological loop as a language learning device. Psychological Review, 105:158–173. Gupta, P. (1996). Word learning and verbal short- term memory: A computational account. In Cottrell, G. W. , editor, Proceedings of the Eighteenth Annual Meeting of the Cognitive Science Society, pages 189– 194. Lawrence Erlbaum, Mahwah, NJ. Gupta, P. (2003). Examining the relationship between word learning, nonword repetition, and immediate se- rial recall in adults. Quarterly Journal of Experimental Psychology (A), 56:1213–1236. Gupta, P. (2004). Primacy and recency in nonword rep- etition. Memory. In press. Gupta, P., MacWhinney, B. , Feldman, H. , and Sacco, K. (2003). Phonological memory and vocabulary learning in children with focal lesions. Brain and Language, There are two possible explanations of these re- sults in terms of our previous computational work (Gupta, 1996). The two formulations can be dis- tinguished by diﬀering predictions with regard to correlations between ISR, nonword repetition, and word learning. The original formulation explains the fact that these correlations arise developmen- tally but predicts their absence in adults. An al- ternative formulation predicts that such correlations obtain not only developmentally, but also in adults. We conducted two experiments to examine whether ISR, nonword repetition, and word learning are cor- related in adults (Gupta, 2003). The results indi- cated that the developmental relationships between all three abilities also exist in adults, thus support- ing the revised model over the original model.