“Same-Different” Reaction Times to Consonants, Vowels, and Syllables

It has been proposed that phonetic segments are encoded into perceptual units of syllable size. The aim of this study is to investigate how consonant and vowel information is transmitted (i.e., serial vs parallel), and to what extent auditory and phonetic levels of analysis may interact in perceptual analysis. Synthetic CV syllables, /ba/, /bæ/, /da/, and /dæ/, were arranged to produce four types of stimulus pairs: (1) consonant same-vowel same (CS-VS, e.g., /ba/-/ba/); (2) consonant same-vowel different (CS-VD, e.g., /ba/-/bæ/); (3) consonant different-vowel same (CD-VS, e.g., /ba/-/da/); and (4) consonant different-vowel different (CD-VD, e.g., /ba/-/dæ/). Same-different reaction times (RTs) were obtained separately for consonants, vowels, and syllables. In the consonant and vowel conditions, RTs for “same” responses were faster when the irrelevant feature was the same (i.e., CS-VS); “different” response RTs were faster when the irrelevant feature was different (CD-VD). In the syllable condition, RTs for different responses were faster when the vowel was different and the consonant was the same (i.e., CS-VD) than when the consonant was different and the vowel was the same (i.e., CD-VS). This suggests that vowel information may be more easily accessible for a comparison than consonant information. These results provide evidence for the parallel transmission of information about stop consonants and vowels in syllables, and an interaction of auditory and phonetic levels of processing in speech perception.