Maternal Infant Eye-to-Eye Gaze

Visual following and visual fixation are among the earliest intentional behaviors produced by human infants, and the most salient visual stimuli for an infant in the first months of life are faces and, in particular, eyes. This is likely to be especially true for human babies, because of the strong visual contrast between our white sclera and darker iris. Eye-to-eye contact in humans starts to appear already in the infant’s 4th week of life, and there is a dramatic increase in face fixations between 5 and 7 weeks. While it is almost certainly lacking any kind of true social relevance for the infant at this point, it is a strong bonding interaction between mothers and infants. Amount of eye-to-eye contact has been experimentally increased by having mothers imitate their infants, suggesting that this behavior is indicative of the quality of the mother-infant relationship. Sex-differences in eye-contact behavior have been found in 12-month-old infants, with females making more eye contact with males, and fetal testosterone levels being inversely correlated to amount of eye-contact behavior produced. In populations with developmental disorders, infants with Down’s syndrome begin making eye-contact later than normal infant, but then sustain it for longer periods of time, while infants with ASD tend to avoid eye-contact altogether.

Studies of other apes have shown that, at least in captivity, chimpanzees engage in mutual gaze with increasing frequency between infant ages of 0-2 months, establishing eye-to-eye contact as often as 28 times per hour by the age of 2 months. Mother-infant mutual gaze in chimpanzees has been observed as early as 2 weeks of age, and when these are encouraged, as in the case of nursery rearing, infants are capable of sustained face-to-face interactions. These developmental changes seem to be due to changes in infant visual behavior, rather than the mother’s, as the amount of time that female chimpanzees spent looking at their infant’s face did not vary over this period of time. Mutual gaze between mothers and infants is much rarer in primates other than humans and chimpanzees, possibly because of the stronger aggressive salience of direct stare in these species.