The Influence of Neighborhood Density on Phonetic Categorization in Aphasia

Abstract

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Neighbourhood density effects in auditory non‐word processing in aphasic listeners

“…The results do agree with the Boyczuk and Baum (1999) study, mentioned in the introduction, who also found that neighbourhood density affected performance of the same three groups of participants equally. It must be noted again that their study was not designed to investigate initial lexical activation, but heuristic processes used in phonetic categorization.…”

“…Given that Broca's aphasics showed a heavier reliance on lexical strategies in an earlier study (i.e. a larger lexical effect than controls on a phonetic categorization task; Blumstein, Burton, Baum, Waldstein, and Katz, 1994), Boyczuk and Baum (1999) initially expected a larger neighbourhood density effect for non-fluent aphasics than for fluent aphasics and control participants. Although no significant interactions between density effect and participant group were found, the density effect was numerically largest for the fluent patients.…”

“…Although no significant interactions between density effect and participant group were found, the density effect was numerically largest for the fluent patients. Boyczuk and Baum (1999) then suggest that neighbourhood density in fact exerts a greater influence on the fluent aphasics' performance because they tend to 'over-activate' the lexicon. Thus, even though the authors expected heavier reliance on (post-hoc) lexical strategies to be influenced by neighbourhood density, the numerically largest density effect for the fluent patients seemed more in accordance with initial lexical over-activation.…”

“…An earlier study on neighbourhood density effects in aphasia is that of Boyczuk and Baum (1999), who investigated the effect of neighbourhood density on phonetic categorization by fluent aphasics, non-fluent aphasics, and age-matched controls. It is important to note, however, that phonetic categorization may tap a different (i.e.…”

“…later) type of processing than the priming and lexical decision studies mentioned above. Boyczuk and Baum (1999) carried out phonetic identification experiments in which subjects were required to label syllable-initial stop consonants varying along a continuum. The endpoints of the continuum differed in terms of lexical status and neighbourhood density values.…”