Infants' attraction to infant vocalizations - A catalyst for infant development

Infant vocalizations play a key role in infant behavior and development, yet we know very little about how infants perceive speech signals with infant vocal properties. In this perspective paper, we summarize recent developmental studies capitalizing on technical breakthroughs in speech synthesis that have allowed for rigorous exploration of this topic. The findings indicate that infants prefer to listen to speech signals with vocal resonances that specify a small, infant-sized vocal tract; this preference is robust and distinct in some ways from infants' attraction to infant-directed speech. This infant talker bias may support infants' speech recognition skills and there is growing evidence that it is also tied to infants' own emerging vocal production abilities. These findings further validate prominent views of speech development, including the articulatory filter and the analysis-by-synthesis hypotheses. Related work in our lab shows that adults also display a strong attraction to infant vowel sounds, adding weight to calls for an expanded and multimodal infant schema. Converging evidence that both infants and adults find infant vocalizations appealing also provides critical support for the fitness-signaling perspective on infant endogenous vocalization. We argue that the infant talker bias has a positive impact on multiple levels, shaping receptive, expressive, and motivational aspects of infant development. The infant talker bias also plays a central role in caregiving behaviors and infant-directed speech. The perceptual potency of infant speech is a catalyst for infant development and also for meaningful and innovative research.