The early development of joint attention in infants with autistic disorder using home video observations and parental interview.

Researchers watched old home videos of 20 babies who were later diagnosed with autistic disorder. They also asked parents when they first noticed problems.

Two raters scored every clip for eye contact, smiling, and joint attention. They compared the babies to 20 typical siblings from the same families.

By 6 months the ASD babies already made less eye contact and smiled less. Joint attention gaps showed up a little later, between 9 and 12 months.

The problems got worse each month. Parents first worried around 8 months, but most did not act until age 2.

Spriggs et al. (2015) used eye-tracking and saw the same early decline. Their data show the lost eye contact never bounces back, which backs up the video results.

Maddox et al. (2015) filmed high-risk siblings at 11 months. They also saw lower social engagement, proving the pattern holds in different samples.

Harrop et al. (2018) adds a twist: girls with ASD keep more face looking than boys. So the early dip may be harder to spot in baby girls without sex-specific norms.

You can start screening before the first birthday. Watch for fewer shared smiles and fleeting eye contact during everyday play. Flag these signs and teach parents simple turn-taking games that reward face looking. Early action may bend the developmental path.