Infant perception of atypical speech signals.

The ability to decode atypical and degraded speech signals as intelligible is a hallmark of speech perception. Human adults can perceive sounds as speech even when they are generated by a variety of nonhuman sources including computers and parrots. We examined how infants perceive the speech-like vocalizations of a parrot. Further, we examined how visual context influences infant speech perception. Nine-month-olds heard speech and nonspeech sounds produced by either a human or a parrot, concurrently with 1 of 2 visual displays: a static checkerboard or a static image of a human face. Using an infant-controlled looking task, we examined infants' preferences for speech and nonspeech sounds. Infants listened equally to parrot speech and nonspeech when paired with a checkerboard. However, in the presence of faces, infants listened longer to parrot speech than to nonspeech sounds, such that their preference for parrot speech was similar to their preference for human speech sounds. These data are consistent with the possibility that infants treat parrot speech similarly to human speech relative to nonspeech vocalizations but only in some visual contexts. Like adults, infants may perceive a range of signals as speech.