Oral exploration and reaching toward social and non-social objects in two-, four-, and six-month-old infants

Abstract

This study investigates tongue protrusion and how it co-develops with gazing and reaching in two-, four-, and six-month-old infants. We assessed these reactions during infant viewing of a human still-face or a manikin. Results showed that two month olds protruded their tongues and gazed toward both stimuli more than infants in the older age groups, and that four and six month olds reached towards the stimuli more than the two month olds. In the still-face condition, there was a positive correlation between tongue protrusion and gazing. In addition, in the still-face condition, infants at four months preferred tongue protrusion over reaching. But this preference did not occur at six months. The results suggest that infants' tongue protrusions and reaching serve an exploratory function in ambiguous social contexts.