Development of smooth pursuit tracking in young infants

Eye and head movements were measured in a group of infants at 2, 3, and 5 months of age as they were attentively tracking an object moving at 0.2 or 0.4 Hz in sinus or triangular mode. Smooth pursuit gain increased with age, especially until 3 months. At 2-3 months, the lag of the smooth pursuit was small for the sinusoidal motion but large for the triangular one. At 5 months, smooth pursuit was leading the sinusoidal motion and the lag for the triangular one was small. Head tracking increased substantially with age and its lag was always large. (C) 1997 Elsevier Science Ltd.