1.When the infant stares at the parent or the person taking care of him, but does not show a happy reaction. 2.At about 5 months of age, the child does not make communicative babbling sounds. 3.Can’t recognize his parents’ voices and doesn’t respond when mom or dad calls his name. 4.Does not make eye contact with others. 5.No babbling sounds until after 9 months of age. 6.Seldom match hand gestures before talking, such as waving small hands. 7.Holds something and repeats an action repeatedly. 8.Can’t say a word at 16 months old. 9.Still can’t make babbling sounds at one week old, and doesn’t make any communicative gestures. 10.Can’t say two words at the age of two weeks. 11.Lack of language skills even though they can talk.