ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
5pSC25. Generalization in the vowel space.
Callier Ctr. for Commun. Disord., Univ. of Texas, 1966 Inwood Rd., Dallas,
Vowels may be represented by a three-dimensional volume of space. The axes
of the volume may be defined in articulatory terms (front--back, high--low,
rounded--unrounded) or in physical terms (F1, F2, F3). Shepard [Science 237,
1317--1323 (1987)] plotted data of Peterson and Barney [ 175--184
(1952)] to show that generalization in the vowel space is an instance of his
universal law of generalization, an exponential decay function with physical
measures on the x axis. This theory is contradicted by the magnet effect [P.
Kuhl, Percept. Psychophys. 50, 93--107 (1991)] which indicates that some areas
of the vowel space are perceptually shrunken. Experiments with naive adult
subjects were executed. Generalization, ABX, and discrimination experiments
were performed using eight cardinal vowels plus intermediate steps between
selected vowels. Results, indicating both Shepard and Kuhl are partially
correct, are best represented by Gluck's scheme [Psych. Sci. 2, 50--55 (1991)]
with the data indicating that it is the distinctive features of vowels that are
perceived categorically. There was little evidence of language-specific effects
for adults. Pilot work with newborns indicate that they organize the vowel
space like adults.