Thought insertion is the delusional belief that one person can think through or into the mind of another. People who suffer from this delusion are frequently unable to differentiate between their own thoughts and thoughts that they believe have been inserted into their minds. In short, this is a feeling that a person’s thought are not their own. People who suffer from this delusion, however, are generally unwilling to accept this diagnosis. This is considered a symptom of schizophrenia.