54 Neurodevelopmental Disorders
Deficits in nonverbal communicative behavi ors used for social interaction are mani-
fested by absent, reduced, or atypical use of  eye contact (relative to cultural norms), ges-
tures, facial expressions, body  orientation, or speech intona tion. An early feature of autism
spectrum disorder is impaired joint attention as manifested by  a lack of pointing, showing,
or bringing objects to share interest with others, or failure to follow someone’s pointing or
eye gaze. Individuals may learn a few functional  gestures, but their re pertoire is smaller
than that of others, and they often fail to use expressive gestures spontaneously in com-
munication. Among adults with fluent language, the difficulty in coordinating nonverbal
communication with speech may give the impr ession of odd, wooden, or exaggerated
“body language” during interactions. Impairme nt may be relatively subtle within indi-
vidual modes (e.g., someone may have relati vely good eye contact when speaking) but
noticeable in poor integration of eye contact, gesture, body posture, prosody, and facial ex-
pression for social communication.
Deficits in developing, maintaining, an d understanding relationships should be
judged against norms for age, gender, and culture. There may be absent, reduced, or atyp-
ical social interest, manifested by rejectio n of others, passivity, or inappropriate ap-
proaches that seem aggressive or disruptive . These difficulties are particularly evident in
young children, in whom there is often a lack of shared social play and imagination (e.g.,
age-appropriate flexible pretend play) and, late r, insistence on playing by very fixed rules.
Older individuals may struggle to understand what behavior is considered appropriate in