The Tuning of Human Neonates’ Preference for Speech

Abstract

Human neonates prefer listening to speech compared to many nonspeech sounds, suggesting that humans are born with a bias for speech. However, neonates' preference may derive from properties of speech that are not unique but instead are shared with the vocalizations of other species. To test this, thirty neonates and sixteen 3-month-olds were presented with nonsense speech and rhesus monkey vocalizations. Neonates showed no preference for speech over rhesus vocalizations but showed a preference for both these sounds over synthetic sounds. In contrast, 3-month-olds preferred speech to rhesus vocalizations. Neonates' initial biases minimally include speech and monkey vocalizations. These listening preferences are sharpened over 3 months, yielding a species-specific preference for speech, paralleling findings on infant face perception.

Nonhuman primate vocalizations support categorization in very young human infants

“…First, we document that in human infants, the fundamental process of developmental narrowing extends well beyond purely perceptual discriminations and preferences (1,(5)(6)(7). Perceptual narrowing is well underway within the first months of life.…”

“…Perceptual narrowing is well underway within the first months of life. For example, neonates' listening preferences, which include both human and nonhuman primate vocalizations, give way to a strong preference for human over nonhuman vocalizations by 3 mo (1,5). However, despite their clearly-tuned preference for human vocalizations, nonhuman primate vocalizations conferred precisely the same conceptual advantages at 3 and 4 mo as human vocalizations, an advantage that by 6 mo was tuned specifically to human vocalizations.…”

“…Certainly, experience with human language is instrumental in infants' first months of life (1,5,7,29). Infants may quickly learn that human language heralds interesting visible events or brings with it rewarding affective experiences.…”

“…1). By 3 mo, infants discriminate vocalizations of humans from those of nonhuman primates (1,14). We selected a lemur vocalization because although it differs distinctly from human vocalizations, it nonetheless shares certain acoustic properties with infant-directed speech.…”

“…At birth, they prefer listening to the vocalizations of human and nonhuman primates over artificial sounds; within months, as their listening preferences narrow, they become attuned to human speech, and to their own native language(s) in particular (1)(2)(3)(4)(5)(6)(7).…”