Vowel Perception Asymmetry in Auditory and Phonemic Listening

This paper reports the results a vowel perception study in which two groups of listeners discriminated among pairs of the vowels [e], [], and [o]. One group was in an auditory listening condition where feedback required listeners to detect within-category differences and the ISI was short. The other group was in a phonemic listening condition where feedback was based on vowel category membership and the ISI was long. Reaction time to discriminate [e]/[o] pairs and []/[e] pairs showed different asymmetry patterns in the two listening conditions. In the auditory condition, the order [e o] had shorter reaction times than did the order [o e] while in the phonemic condition the order [o e] was discriminated more quickly. The results can be modeled with Tversky's (1977) similarity index where the only difference between the auditory and phonemic listening conditions is a reduction in the amount of salience given to the referent of the comparison in the phonemic condition.