Vowel similarity, connectionist models, and syllable structure in motor programming of speech

Using a response-priming procedure, five experiments examined the effects of vowel similarity on the motor programming of spoken syllables. In this procedure, subjects prepared to produce a pair of spoken syllables as rapidly as possible, but sometimes had to produce the syllables in reverse order instead. The spoken responses consisted of consonant-vowel-consonant (CVC) syllables whose medial vowels were /i/, /I/, /λ/, and /α/. Performance was measured as a function of the phonetic relationship between the vowels in a syllable pair. Longer response latencies occurred for syllable pairs that contained similar vowels (e.g., /i/ and /I/) than for syllable pairs that contained dissimilar vowels (e.g., /i/ and /λ/). This inhibitory vowel-similarity effect occurred regardless of whether the initial consonants of the syllables in a pair were the same or different. However, it decreased substantially when the final consonants of the paired syllables were different. These results suggest that a lateral-inhibition mechanism may modulate the motor programming of vowels during speech production. They also provide evidence for the integrity of vowel-consonant (VC) subunits in syllables.