Rebecca is providing clinical social work in a children’s hospital. One of her clients is a 4-year-old little boy with autism. Communication with him has been difficult and he will not look at her when she is speaking. Rebecca notices he likes to look at the framed artwork on his hospital room wall. The social worker brings in pictures of a little boy putting on his pajamas for bed. The autistic child stares at the pictures and then pulls his own pajamas out of a drawer. Rebecca has used what form of communication?