The characteristics of Asperger syndrome vary from one person to another but are generally divided into three main groups.

Difficulty with social communication

If you have Asperger syndrome, understanding conversation is like trying to understand a foreign language. People with Asperger syndrome sometimes find it difficult to express themselves emotionally and socially. For example, they may:

• have difficulty understanding gestures, facial expressions or tone of voice
• have difficulty knowing when to start or end a conversation and choosing topics to talk about
• use complex words and phrases but may not fully understand what they mean
• be very literal in what they say and can have difficulty understanding jokes, metaphor and sarcasm. For example, a person with Asperger syndrome may be confused by the phrase 'That's cool' when people use it to say something is good.

In order to help a person with Asperger syndrome understand you, keep your sentences short - be clear and concise.

Difficulty with social interaction

I have difficulty picking up social cues, and difficulty in knowing what to do when I get things wrong.

Many people with Asperger syndrome want to be sociable but have difficulty with initiating and sustaining social relationships, which can make them very anxious. People with the condition may:

• struggle to make and maintain friendships
• not understand the unwritten 'social rules' that most of us pick up without thinking. For example, they may stand too close to another person, or start an inappropriate topic of conversation
• find other people unpredictable and confusing
• become withdrawn and seem uninterested in other people, appearing almost aloof
• behave in what may seem an inappropriate manner.

Difficulty with social imagination

We have trouble working out what other people know. We have more difficulty guessing what other people are thinking. People with Asperger syndrome can be imaginative in the conventional use of the word. For example, many are accomplished writers, artists and musicians. But people with Asperger syndrome can have difficulty with social imagination. This can include:

• imagining alternative outcomes to situations and finding it hard to predict what will happen next
• understanding or interpreting other peoples thoughts, feelings or actions. The subtle messages that are put across by facial expression and body language are often missed
• having a limited range of imaginative activities, which can be pursued rigidly and repetitively, eg lining up toys or collecting and organising things related to his or her interest.