Communication: language develops slowly or not at all, especially by 16 months; words may be used without attaching the usual meaning to them; gestures may be used instead of words; may have short attention spans; Immature rhythms of speech, limited understanding of ideas and the use of words without attaching the usual meanings to them; may have a loss of speech at any age
Social interaction: individual may spend time alone rather than with others; may show little interest in making friends; may be less responsive to social cues such as eye contact or smiles; No large smiles or other expressive, joyful facial expressions by six months; No back-and-forth sharing of sounds, smiles, or other facial expressions by nine months; No back-and-forth gestures, such as pointing, showing, reaching, or waving by 12 months.
Sensory Impairment: May have abnormal responses to sensations. May be over-sensitive or under-responsive to pain, light, sound, smell, touch, or balance, the way a child holds his or her body; any one or a combination of these responses may be affected.
Play: may demonstrate lack of spontaneous or imaginative play; may not imitate others’ actions; may not initiate pretend games; Abnormal ways of relating to people, objects and events; Lack of interest in peer relationships, may prefer to be alone.
Behaviors: may be overactive or very passive; may throw frequent tantrums for no apparent reason; may become over-focused or absorbed with a single item, idea, or person; many demonstrate apparent lack of common sense; may display aggressive behavior or injure self; may have repetitive use of motor movements (e.g., hand-flapping, twirling objects); Persistent fixation on parts of objects
Click here for a diagnostic checklist of Autism.