At 7 months old, children who are later diagnosed with autism take a split second longer to shift their gaze, as compared with typically developing children of the same age. Researchers supported by the National Institutes of Health measured a 25 to 50 millisecond difference when measuring eye movements and visual attention—too brief a time period to be observed through social interactions with the infant.
The delay could be attributed to differences in the structure and organization of developing neurological circuits in the child’s brain. Effectively shifting attention in infancy is considered to be an important factor in later social and cognitive development. These brief delays could precede later symptoms of autism such as difficulty making eye contact or following an adult’s pointing finger. These problems typically surface after a child turns 1, and autism is generally not diagnosed until after 3 or 4 years of age.
The study, which appears in the American Journal of Psychiatry, links differences in reaction times to differences in the developing brain, which in turn may influence the way babies absorb and respond to their environment in more pronounced ways over time. The brain’s channels for communication are forming rapidly in early infancy, and slight differences at this age could offer a window into future problems at a later age.
To gauge shifts in visual attention and gaze, the researchers used eye tracking equipment to mark the exact timing of eye movements. Infants sat on their parent’s laps and watched images appear on a computer monitor. In one part of the test, an image would appear in the center of the screen to attract the infant’s gaze, and would then disappear. After a brief delay, another image would appear at the edge of the screen.
The research is part of the ongoing Infant Brain Imaging Study, which is supported through the NICHD’s Autism Centers of Excellence Program.