A New Look at Infant Preference for Infant-Directed Speech

Infants' preference for infant-directed speech has been reliably demonstrated throughout the first year of life using looking time measures. Though widely used in developmental science, interpretations of looking time are often rich, making assumptions about underlying mental states. In addition to being driven by preference, infant visual fixations can be caused endogenously by other factors such as arousal. We present a new methodology for measuring infant preference - the conditioned place preference paradigm (CPP), a widely used tool in animal research - that allows researchers to disentangle arousal and preference. Using CPP, infants' preference for infant-directed speech was replicated, but only when the speech was paired with a video of a social partner. We propose a new hypothesis, that preference for infant-directed speech is driven by its strong social signal value.