Four parent-guided training procedures aimed at facilitating independent reaching were compared in 36 three-month-old infants recruited for this study and 36 infants taken from previously published reports. Training procedures systematically varied whether parental encouragement to act on external objects was provided, and whether self-produced experiences of moving an object were present. Reaching behavior was assessed before and after training, and face preference was measured after training by recording infants’ eye gaze in a visual-preference task. Results showed that simultaneous experiences of parental encouragement and self-produced object motion encouraged successful reaching and face preference. Neither experience in isolation was effective, indicating that both external encouragement and self-produced action experiences are necessary to facilitate successful reaching. However, experiences with self-produced object motion increased infants’ face preference. This result provides evidence for a developmental link between self-produced motor experiences and the emergence of face preference in three-month-old infants.
Libertus is with the Center for Autism and Related Disorders, Kennedy Krieger Institute, Baltimore, MD. Needham is with the Dept. of Psychology and Human Development, Vanderbilt University, Nashville, TN.