Macaques show context effects in speech perception

Abstract

The phonetic distinction between the stop consonant /b/ and semivowel /w/ is cued primarily by duration of the initial formant transition. Syllable duration, however, is a context that influences human adults' and infants' perception of this distinction. For example, when overall syllable duration is long (296 ms), infants show poor discrimination of syllables with transition durations of 16 and 40 ms, but good discrimination of syllables with transition durations of 40 and 64 ms. However, when overall syllable duration is short (80 ms), the opposite is true [P. D. Eimas and J. L. Miller, Science 209, 1140–1141 (1980)]. The current study addresses whether rhesus and Japanese macaques' perception of the /b-w/ distinction is also influenced by syllable duration: Six CV syllables used in the Eimas and Miller (1980) study were presented to five macaques using a same-different discrimination paradigm. Results showed that macaques' pattern of discrimination was similar to the pattern shown by infants, thus supporting an auditory-based mechanism for the effect of syllable duration in phonetic perception. [Work supported by NSF and NIH.]