Psychologist Ami Klin of Yale University’s Child Study Center and his colleagues conducted the experiments. Link PHYSORG:
Individuals with autism spectrum disorders (ASD) tend to stare at people's mouths rather than their eyes. Now, an NIH-funded study in 2-year-olds with the social deficit disorder suggests why they might find mouths so attractive: lip-sync—the exact match of lip motion and speech sound. Such audiovisual synchrony preoccupied toddlers who have autism, while their unaffected peers focused on socially meaningful movements of the human body, such as gestures and facial expressions.
A eureka moment in the research came when researchers followed up on a clue from children's responses to audiovisual synchrony embedded in a nursery rhyme cartoon.
While it was known that people with autism do not spontaneously orient to social signals, it was unclear what early-emerging mechanism may contribute to that. Nor was it clear exactly what they were attending to instead. To find out, Klin, Jones and colleagues tracked the eye movements of two-year-olds with and without the disorder while they looked at cartoon animations on split-screen displays.
[for a look/listen to this experiment, click on the link and scroll down to teh video]
Eye-tracking data shows where toddlers in each of three groups were looking during the Pat-a-Cake animation. It plays upright and forward on the left side of screens, upside down and in reverse on the right side. Red cross indicates where the child was looking. Toddler with autism is focused on audiovisual synchrony of hands clapping, while typically developing and developmentally delayed toddlers focus on face.
The researchers borrowed a technique from the video game industry, called motion capture. They then reduced the movements to only points of light at each joint in the body, like animated constellations. These cartoons played normally - upright and forward - on one half of the screen, but upside-down and in reverse on the other half. The inverted presentation engages different brain circuits and is known to disrupt perception of biological motion in young children. The normal soundtrack of the actor's voice, recorded when the animations were made, accompanied the presentations.