According to the American Academy of Pediatrics' developmental milestones, by the first birthday, typical toddlers can say one or two words, turn when they hear their name, and point when they want a toy. When offered something they do not want, toddlers make it clear with words, gestures, or facial expressions that the answer is "no."
For children with ASD, reaching such milestones may not be so straightforward. For example, some children with autism may:
- Fail or be slow to respond to their name or other verbal attempts to gain their attention
- Fail or be slow to develop gestures, such as pointing and showing things to others
- Coo and babble in the first year of life, but then stop doing so
- Develop language at a delayed pace
- Learn to communicate using pictures or their own sign language
- Speak only in single words or repeat certain phrases over and over, seeming unable to combine words into meaningful sentences
- Repeat words or phrases that they hear, a condition called echolalia
- Use words that seem odd, out of place, or have a special meaning known only to those familiar with the child's way of communicating.
Even children with ASD who have relatively good language skills often have difficulties with the back and forth of conversations. For example, because they find it difficult to understand and react to social cues, children with Asperger syndrome often talk at length about a favorite subject, but they won't allow anyone else a chance to respond or notice when others react indifferently.
Children with ASD who have not yet developed meaningful gestures or language may simply scream or grab or otherwise act out until they are taught better ways to express their needs. As these children grow up, they can become aware of their difficulty in understanding others and in being understood. This awareness may cause them to become anxious or depressed.