By 9 months, which finding may be present in a child with autism?

• A. Ability to share sounds and smiles in back-and-forth interactions
• B. Little/no back-and-forth sharing of sounds, smiles, or other facial expressions
• C. Early babbling and responding to name
• D. Strong preference for social play

Answer: (B)

The main idea here is social-communication development in infancy. By around 9 months, typically developing infants engage in back-and-forth exchanges of sounds, smiles, and facial expressions—the kind of proto-conversations that show social reciprocity. When a child with autism shows little or no back-and-forth sharing of sounds, smiles, or other facial expressions, it signals a disruption in this early social-communication pattern. This reduced reciprocal interaction is a common early indicator of autism and helps distinguish it from typical development.

The other options reflect behaviors more in line with typical development: sharing sounds and smiles in back-and-forth interactions indicates normal social engagement; early babbling and responding to name are expected milestones; and while some children with autism may eventually enjoy social play, a strong preference for social play is not characteristic of autism in the same way that reduced reciprocal sharing is.