What Can a Baby See?
Human infants have limited vision. At birth there are many immaturities in the eyes and visual parts of the brain. Newborns behave as though they are looking through a dense fog – objects have to be bold, bright, and large to generate a response.
Visual responses develop very rapidly over the first 3-6 months. Infants move their eyes together and accurately by around 3 months, which soon leads to good depth perception.
They start to respond to colored targets by around 2 months of age, and the development of acuity (detailed vision) takes somewhat longer. Adult levels of acuity are not reached until the first years after birth. This means that very young babies are not capable of detecting small and subtle features in a face – in fact they will frequently spend more time looking at the edge of a face than at the eyes.
Babies are also born with a wide range of refractive errors (spectacle prescriptions). They are typically far-sighted (hyperopic/hypermetropic) at birth, which means that the eye is underpowered. Fortunately, at this age infants can typically exert extra focusing effort to increase the eye’s power. The range of refractive errors usually reduces over the first two years or so after birth.
It is extremely important that a baby’s visual system experiences sharp, focused images during the first few years of early development of the visual parts of the brain. If the brain does not receive equal, sharp images from both eyes during the early ‘critical period’ of development, it will develop to use more information from the stronger eye, leading to ‘lazy eye’ or amblyopia in the weaker eye. The child then needs to have help to stimulate vision in the weaker eye. For this reason many organizations now recommend that infants’ eyes are examined at some point during their first year, to catch potential problems early.
This experience-dependent development is the central theme of research in our laboratory. We ask, “How does the visual system use the available visual information to refine its development?”
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