Which of the following is a common symptom of autism in a 15-month-old?

A common symptom of autism in a 15-month-old is the lack of response when called by name. Typically developing children in this age group usually respond to their name being called, demonstrating an understanding of social cues and engagement with caregivers. However, many children on the autism spectrum may not show this response, which can indicate difficulties in social communication and interaction.

In developmental terms, responding to one's name is an early indicator of social awareness and engagement with others. When a child consistently does not respond to their name, it can signal challenges in social reciprocity, which is a hallmark of autism.

The other options denote behaviors that are generally expected at this stage of development. Speech in complete sentences is atypical for a 15-month-old, as most children at this age are still acquiring single words and may not be putting them together into sentences. Looking at where someone points shows joint attention and social engagement, which are typically developing skills by this age. Enjoying play with other children also reflects social development and is usually observed in typically developing toddlers.