The gaze stability of 4-to 10-week-old human infants

The relationship between gaze stability, retinal image quality, and visual perception is complex. Gaze instability related to pathology in adults can cause a reduction in visual acuity (e.g., Chung, LaFrance, & Bedell, 2011). Conversely, poor retinal image quality and spatial vision may be a contributing factor to gaze instability (e.g., Ukwade & Bedell, 1993). Though much is known about the immaturities in spatial vision of human infants, little is currently understood about their gaze stability. To characterize the gaze stability of young infants, adult participants and 4- to 10-week-old infants were shown a dynamic random-noise stimulus for 30-s intervals while their eye positions were recorded binocularly. After removing adultlike saccades, we used 5-s epochs of stable intersaccade gaze to estimate bivariate contour ellipse area and standard deviations of vergence. The geometric means (mail standard deviations) for infants' bivariate contour ellipse area were left eye = -0.697 +/- 0.534 log(degrees(2)), right eye = -0.471 +/- 0.367 log(degrees(2)). For binocular vergence stability, the infant geometric means (with standard deviations) were horizontal = -1.057 +/- 0.743 log(degrees), vertical = -1.257 +/- 0.573 log(degrees). These values were all not significantly different from those of the adult comparison sample, suggesting that gaze instability is not a significant limiting factor in retinal image quality and spatial vision during early postnatal development.