Early signs of schizophrenia may not be noticed by family and friends. The person develops peculiar behavior, begins talking nonsense and has unusual perceptions. These more severe symptoms are usually the reason for seeking treatment. Delusions are unusual beliefs that are not based in reality. For example, people suffering from schizophrenia might believe that someone can hear their thoughts or control their feelings, actions or impulses.
Hallucinations are distortions of the senses.
Auditory hallucinations cause people to hear sounds that are not there. Visual hallucinations cause people to see things that do not exist. Tactile hallucinations are sensations without cause, like burning or itching. Olfactory hallucinations, smelling non-existent odors, also occur. Preoccupations are thoughts which take on more importance in the sufferer's mind than they normally would.