• Lack of social smile, lack of appropriate facial expression, poor attention, impaired social interaction
• Ignoring people, preference of aloness, lack of eye contact, lack of appropriate gestures, lack of emotional expression, less looking at others, less pointing, less showing objects in the second year.

In the first year of life there are usually no clear discriminating features but parental concerns should be elicited
Between 2 and 3 years of age, concerns in the following areas should prompt referral

1. Communication

Impairments of language development, especially comprehension; unusal use of language; poor response to name; deficient non-verbal communication - for example, lack of pointing and difficulty following a point and failure to smile socially to share enjoyment and respond to the smiling of others

Absolute indicators for referral

• No babble, pointing, or gesture by 12 month
• No single word by 18 months
• No two word spontaneous (non-echoed) phrases by 24 months
• Any loss of any language or social skills at any age

2. Social impairments

Limitation in, or lack of imitation of, actions (for example, clapping);lack of showing with toys or other objects; lack of interest of other children or odd approaches to other children. Minimal recognition or responsiveness to other people´s happiness or distress; limited variety of imaginative play or pretence, especially social imagination (that is, not jointing with others in shared imaginary games), "in his or her own world"; failure to initiate simple play with others or participate in early social games; preference for solitary play activities; odd relationship with adults (too friendly or ignores)

3. Impairments of interests, activities, and other behaviours

Over-sensititivity to sound or touch; motor mannerisms; bitting, hitting or aggression to peers; oppositional to adults; over-liking for samenuess or inability to cope with change, especially in unstructed setting; repetitive play with toys (for example, lining up objects); turning light switches on and off; regardless of scolding