Discuss specific early pre-verbal communication skills and examine how they can have an impact on language development in typically developing children and children with autism spectrum disorder.

Discuss specific early pre-verbal communication skills and examine how they can have an impact on language development in typically developing children and children with autism spectrum disorder.
Based on the descriptions in the case studies provided:
Compare and contrast the pre-verbal communication skills development of Sally and Erin.
Analyze the specific social communication challenges seen in Sally.
Identify the examples of joint attention, symbol use, and communicative intent seen in Sally during social interactions.