The PMHNP is evaluating a 4-year-old boy who is brought in by his foster mother. The child has been living with her for 1 week, and she is concerned about this behavior. Staff at the day care center he attends report that he displays fear unrelated to particular activities. Even when distressed, he does not seek comfort in, nor respond to, any staff members. What additional information about this child would be important in determining whether his symptoms represent reactive attachment disorder (RAD) or autism spectrum disorder (ASD)?