ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4pSC8. Competition and categorization: The effect of choice set on vowel category structure.

D. A. Galama

Terrance M. Nearey

Dept. of Ling., Univ. of Alberta, 4-32 Assiniboia Hall, Edmonton, AB T6G 2E7, Canada

The effect of competition on the perception of category peaks and on goodness judgments was examined. A 48-step vowel continuum spanning the /I--(cursive beta)--(ae ligature)/ range was synthesized by varying F1 and F2. Subjects listened to multiple presentations of all 48 vowel stimuli in five separate conditions, with nature of the choice set as the dependent variable. The five choice sets were: /I--(cursive beta)--(ae ligature)/, /I--(cursive beta)/, /(cursive beta)--(ae ligature)/, /I--(ae ligature)/, and /(cursive beta)/. For each of the first four conditions, subjects were asked to simultaneously categorize and provide category goodness ratings for the vowel stimuli. In the fifth condition, subjects were required to provide goodness judgments only, thereby indicating perceived degree of membership to the category /(cursive beta)/. Identification and goodness functions corresponded well to each other, with changes in the competition paradigm affecting both of these functions similarly. Also, location of category peaks and range of goodness judgments exceeding 90% were found to remain relatively stable, regardless of the number of categories in the choice set. While the results of various normalization studies suggest that the structure and location of vowel category peaks is highly affected by various contextual factors, they appear to be relatively unaffected by the nature of category competition. [Work supported by SSHRC.]