CATEGORIES AND CONTEXT IN THE PERCEPTION OF ISOLATED STEADY-STATE VOWELS

The noncategorical perception of isolated vowels has been attributed to the availability of auditory memory in discrimination. Two experiments were conducted, using 32 undergraduates as Ss. In Exp I, using vowels from an /i/-/I/-/ε/ continuum in a same-different (AX) task and comparing the results with predictions derived from a separate identification test, it was demonstrated that vowels are perceived more nearly categorically if auditory memory is degraded by extending the interstimulus interval and/or filling it with irrelevant vowel sounds. In Exp II, a similar paradigm was used, but in addition to presenting a separate identification test, labeling responses were elicited to the AX pairs used in the discrimination task. It was found that AX labeling responses predicted discrimination performance quite well, regardless of whether auditory memory was available, whereas the predictions from the separate identification test were more poorly matched by the obtained data. The AX labeling responses showed large contrast effects (both proactive and retroactive) that were greatly reduced when auditory memory was interfered with. It is concluded from the presence of these contrast effects that vowels are not perceived categorically. However, it seems that by taking the effects of context into account properly, discrimination performance can be accurately predicted from labeling data, suggesting that vowel discrimination, like consonant discrimination, may be mediated by phonetic labels. (33 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1979 American Psychological Association.