Speech perception in the human infant and rhesus monkey.

In summary, a complete understanding of the development of infant speech perception requires not only research guided by efforts to construct an ontogenetic timetable of the infant's speech discriminative abilities, but investigations of the phylogenetic bases of these ontogenetic abilities, and much more concern for how the microgenetic development of speech perception affects our assessment of ontogenetic and phylogenetic development. The data presented in this paper on the categorical discrimination of place of articulation in rhesus monkeys and human infants illustrates the importance of considering phylogenetic and microgenetic aspects of development in explaining the origin of some of the infant's phonetic capabilities. In addition to continuing to explore the upper bounds of the infant's "phonetic" perceptual abilities, the adaptation of feature detectors, and short-term memory processes in the assessment of infant and non-human primate speech discrimination. Only then we will be able to appreciate fully the significance of a study demonstrating categorical discrimination in human infants .