3. Not Responsive to Human Interaction
By nature, non-autistic children are known for their social behavior. We may have to stop a child from being too friendly with strangers, but this could be the other extreme with autistic babies. In fact, autistic babies may not be seen taking an interest in regular development games and habits.
This could include socializing with other people, imitating them, mimicking their facial expressions, or even holding on to their hands or fingers. You would most likely to notice this unusual behavior when a child is around one year of age. Proper socializing behavior is usually manifested by 18 months.
Anything unusual is going to be more pronounced when they become part of a group with other children of the same age. By the time they’re three, they might not even take an interest in regular toys; a year later, they may seem to be pointedly ignoring everyone.