VOT discrimination by four to six and a half month old infants from Spanish environments.

Thirty 4–6.5 mo-old-infants from monolingual Spanish speaking homes were tested for discrimination of bilabial stop consonants differing in VOT. Discrimination was determined by the habituation and dishabituation of the orienting reflex as indexed by cardiac deceleration. Subjects were placed in one of three groups of ten subjects each. The three groups were used to determine whether bilabial stops with VOT values of ?60 and ?20 msec, ?20 and +20 msec or +20 and +60 msec could be discriminated. Subjects were presented eight trial blocks of ten repetitions of a CV syllable; these eight trial blocks were followed by two trial blocks of ten repetitions of a different CV syllable. The only difference between the CV syllables presented during the first eight and the last two trial blocks was the VOT value of the bilabial stop consonants. Subjects in the ?20 and +20 msec group showed no signs of being able to discriminate these stimuli while the subjects in the ?60 and ?20 msec group and the +20 and +60 msec group did. These results correspond to those reported for infants from English speaking families but do not correspond to those reported for Spanish speaking adults. Thus, the failure to find evidence of discrimination in the ?20 and +20 msec group suggests that experience has little effect in determining bilabial stop phonetic categories in 4–6.5 mo-old infants.