The development of infants' use of property-poor sounds to individuate objects

There is evidence that infants as young as 4.5 months use property-rich but not property-poor sounds as the basis for individuating objects (Wilcox, Woods, Tuggy, & Napoli, 2006). The current research sought to identify the age at which infants demonstrate the capacity to use property-poor sounds. Using the task of Wilcox et al., infants aged 7 and 9 months were tested. The results revealed that 9- but not 7-month-olds demonstrated sensitivity to property-poor sounds (electronic tones) in an object individuation task. Additional results confirmed that the younger infants were sensitive to property-rich sounds (rattle sounds). These are the first positive results obtained with property-poor sounds in infants and lay the foundation for future research to identify the underlying basis for the developmental hierarchy favoring property-rich over property-poor sounds and possible mechanisms for change.