Milestones in Visual Development

Infant Vision Lab
The Eunice Kennedy Shriver Center

University of Massachusetts Medical School
200 Trapelo Road - Waltham, MA - 02452

The study of infant vision is a relatively young science. Yet in the last 25 years we have learned a great deal about how infants see. The following is some of what we now know.

Focusing Ability-- Focusing is when special muscles change the shape of the lens of the eye to form a clear image of the world on the back of the eye (the retina). Before 2 months of age, infants' eyes have the ability to focus distant objects as well as close objects; but they do not focus very accurately. Sometimes they will focus too close (in front of the object), sometimes too far (behind the object). Although newborns’ eyes are capable of focusing things at the horizon, as well as things quite close to their face, many baby books still incorrectly say that infants can only focus 7 to 10 inches in front of their face. In fact, infants are generally far-sighted at birth, and grow out of it over the first years of life. By 2-3 months of age most infants can focus accurately.

Eye Coordination and Tracking — Even newborn infants will follow an object with their eyes (this is tracking) if the object is large enough, has enough contrast, and is moving slowly. However, their eyes will follow the object with "jerky" motions, unlike adults who track very smoothly. Newborns will not always track, especially if they are in a room with lots of activity, noise and other things to look at. By 3 months of age they are able to follow an object quite smoothly, as long as it is not moving too fast.

Depth Perception — Infants are not born with depth perception.  The images on the back of our eyes are flat and 2-dimensional.  To create a 3-dimensional view of the world, the brain combines information from the separate images of the two eyes.  Visual experience along with development in the brain neurons responsible for combining images from the two eyes leads to the emergence of binocular depth perception around 3 to 5 months of age.

Seeing Subtle Shades of Gray- Contrast Sensitivity — Infants are born with very poor contrast sensitivity, but by 2.5 to 3 months of age they can see shades of gray almost as well as adults, provided the pattern size is large.  Development of contrast sensitivity is primarily determined by maturation in the neurons of the eye, and to a lesser extent neurons in the brain.

Seeing Color — By two to six weeks of age, infants can distinguish a red object from a green one, even when they are perfectly matched in brightness.  But young infants’ color vision isn’t as rich and sensitive as adults’ color vision because the neurons in the eye that are most sensitive to color are not yet mature.  So infants have trouble detecting faint colors like pastels.

Discrimination of Pattern Details-Vernier Acuity — Visual discrimination of pattern details, like spatial offsets in line elements, is a much more complex task than detecting pattern details or subtle shades of gray.  It requires greater processing in the visual cortex, and develops very gradually.  By one year of age, vernier acuity is still 10 times worse than adults’, and it reaches full maturity by age 14.

Object & Face Recognition -- Although at birth, infants have enough detail vision to be able to see most of the features of your face from arm's length, they tend to be attracted to the borders of objects, especially high-contrast borders. Thus, when looking at a human face, a newborn will pay more attention to the hairline or the edge of the face. By 2 months of age, infants begin to attend to the internal features of a face, such as the nose and mouth, and by 3 to 5 months of age they can tell the difference between mother's face and a stranger's face.