Dr. Sukhi Shergill defines 'Theory of Mind' - the ability of most people to predict what others are thinking.
Theory of mind is a term that’s used to describe the skill that we all have, which is the ability to put ourselves in the place of somebody else and know what they might be thinking or what they might be feeling. So if I look at you and you’re watching a football game or something similar and I see you getting up and shouting "yea, yea, yea!," then I know that your team must be doing pretty well. And if you’re sitting there looking pretty glum and unhappy, I’ll say "hey he’s sad and watching the game, therefore, his team must not be doing very well. If not, he’s feeling a little bit sad." So theory of mind describes the ability to put yourself into somebody else’s mind and think what they might be feeling or thinking. This is a skill - theory of mind is a skill that most people acquire around the age of three or four. So if you try and test children when they’re younger than three or four, they don’t seem to be able to figure out what other people are thinking. But once they grow up, they start developing this skill and by the age of six, they’re pretty good at knowing what other people are thinking. One of the problems in schizophrenia seems to be that patients with a certain form of schizophrenia, which we call negative symptoms, where people are withdrawn, they seem to have a great deal of difficulty in figuring out how other people are thinking. That’s thought to be one of the reasons why they’re quite withdrawn and that’s responsible for some of their symptoms. One of the problems that you see in schizophrenia is that people have a lot of paranoid or persecutory ideas where they feel people are following them or people want to harm them in some way. And this may be an example where this theory of mind or ‘mentalizing,’ being able to work out what somebody else is thinking is going into overdrive. So even though people might not be looking at your or thinking about you, or even directing their comments at you, what you feel is as if they are directing their comments at you and it feels like everything is connected to your own thinking. That seems to be an example of where this theory of mind thing has gone badly wrong.