Table 1.

Cognitive and behavioral features affecting social communication in intellectual disability.

Communication
Concrete or inflexible thinking Difficulties with flow of conversation Difficulties with logical thinking Language disorder (e.g., reduced vocabulary) Stereotyped or repetitive speech* Reduced facial expression and gestures due to motor impairment (e.g., hypotonia, parkinsonism) Decreased pointing due to motor impairment (e.g., hypotonia or hypertonia, reduced hand function, poor motor coordination) Reduced eye contact (e.g., eye gaze avoidance)**
Behavior
Anxiety, general, or social types Hyperactivity or impulsiveness Sensory over-reactivity Irritability Repetitive movements (e.g., body rocking, hand flapping)* Perseverative behavior*

*Common behaviors in intellectual disability, which could be diagnostic RRBs for ASD and/or stereotypic movement disorder.

**Common behavior in fragile X syndrome with or without ASD; related to anxiety.