Symptoms of psychosis are broadly categorized as positive and negative symptoms. Positive symptoms are characterized by the presence of delusions, auditory and visual hallucinations, whereas negative symptoms are characterized by the absence of motivation, unexpressive faces, inattention to personal hygiene, etc.
People with positive symptoms become more sensitive and believed that they are being watched or monitored. They may also believe that friends, or co-workers are trying to hurt them. When their delusion worsens, they become disconnected from reality. For example, he or she believes they can be abducted by aliens, hence avoids leaving the house.
Schizophrenia and delusional disorder are common forms of psychosis.