Diphones, lexical access, and the verbal transformation effect

Abstract

When listeners are presented with a repeating verbal stimulus, adaptation occurs and perception of the stimulus is replaced by perception of a competitor. The present study examines the first of these verbal transformations reported by 180 listeners who were presented with lexical and nonlexical consonantvowel (CV) syllables that varied in frequency-weighted neighborhood density (FWND). These stimuli were produced by pairing the six English stop consonants with a set of three vowels. As expected, the majority of initial illusory forms (78%) were neighbors, differing from the stimulus by a single phoneme, and the proportion of lexical neighbors increased with stimulus FWND. Interestingly, FWND had opposite effects upon the lability of consonants and vowels: There was a strong positive correlation [r=0.79, F(17)=26.2, p<0.0001] between FWND and the number of consonant transformations, and in contrast, there was a strong negative correlation [r=−0.78, F(17)=24.9, p<0.0001] between FWND and the number of vowel transformations. The implications of these and other findings with these simple diphones will be discussed in relation to current activation-competition theories of spoken word recognition. [Work supported by NIH.]