The term psychosis, as a term, is meant to indicate the severity of the illness and does not refer to a specific type of disorder. Instead, the obvious manifestation of a psychotic patient is an impairment in the ability to test reality, often cognitive and affective; such patients are likely to be verbally and behaviorally bizarre, they have various hallucinations, they also cling stubbornly to ideas that conflict with reality, i.e., delusions, and of course exhibit marked confusion and seizures without acknowledging what is wrong with them, i.e., no self-awareness. Most psychotic symptoms may be seen in patients with an organic basis, yet newer research has found that schizophrenia is not necessarily without an organic basis. It is no wonder that many psychiatrists, even famous doctors, look for hallucinations and delusions when diagnosing schizophrenia; as for disorganized speech, abnormal behavior, and impairment of social functioning, all of which occur together, a professional psychiatrist must be alerted early to avoid delays. The final diagnosis depends on the course of the disease and the exclusion of other diseases. The following is a discussion of what hallucinations are: 1. Hallucination is an illusory perception: a perceptual experience that occurs when there is no realistic stimulus acting on the senses. According to the different sensory organs can be divided into hallucinations of hearing, vision, smell, taste, touch, sexual hallucinations, visceral hallucinations and motor hallucinations. Clinical hallucinations of hearing and vision are more common. (1) Auditory hallucination: The content of auditory hallucination is diverse, and the type and nature of sound vary. The most common speech hallucinations include commentary hallucinations and command hallucinations. Commentary hallucinations are when the patient hears someone commenting on his shortcomings and problems. Command hallucinations are when the patient hears someone ordering him to do something, such as refusing food, jumping off a building, or beating someone else, which the patient cannot disobey and therefore can produce behavior that is harmful to himself and society. It can be seen in a variety of psychiatric disorders, especially schizophrenia. (2) Visual hallucination: The content is also rich and varied, and the image can be clear, distinct and specific, but sometimes it is also blurred. If the image of the hallucination is larger than the physical object, it is called visual hallucination (giant image hallucination), and if it is smaller than the physical object, it is visual hallucination (small image hallucination). Hallucinations are most often seen in disorders of consciousness, but can also be seen in states of clear consciousness, such as schizophrenia. There are also situational hallucinations, mostly in infectious psychosis, and non-situational hallucinations, mostly in schizophrenia. (3) Phantom smell (olfactoryhallucination): Mostly unpleasant odors, such as rotten food, burnt objects and chemicals. The content of the phantom smell is often associated with other hallucinations or delusions. If the patient is convinced that the odor he smells is intentionally released by bad people, thus strengthening the belief of persecution delusion, the patient may show corresponding behaviors such as covering the nose or refusing to eat. In temporal lobe damage, phantom sniffing can be the first symptom, and phantom sniffing is also seen in schizophrenia. (4) Gustatoryhallucination: The patient tastes some special or strange taste in food and refuses to eat. It is often accompanied by other hallucinations and delusions, for example, together with phantom smells in schizophrenia. (5) Phantom touch (tactilehallucination): There may be numbness, insect crawling sensation, electric sensation, stabbing sensation, etc.. It can be seen in schizophrenia and organic mental disorders. (6) Visceral hallucination: A strange sensation inside a fixed organ or body, such as feeling that an internal organ is twisting, breaking or perforating, or feeling that insects are crawling inside the organ. These hallucinations are often associated with delusions of hypochondria and delusions of futility. They are more often seen in schizophrenia, depression, etc. According to the nature of hallucinations, they can be divided into true hallucinations and pseudohallucinations: (1) Genuine hallucination: Patients experience the content of hallucinations from external space, such as indoors or outside the yard, and they are perceived directly through the patient’s sensory organs. The hallucination image is distinct and identical to the real thing. (2) Pseudohallucination: The hallucinatory content is produced in the patient’s subjective space, such as inside the brain or body. The hallucination is not obtained through the patient’s sensory organs. The perceived objects are not vivid enough. Most often seen in schizophrenia. Special forms of hallucinations: (1) Functional hallucination: These are characterized by the simultaneous appearance, co-existence and disappearance of hallucinations (usually auditory hallucinations) and realistic stimuli, but they do not merge together (this is different from illusions). The sounds of the real stimuli are usually monotonous sounds, such as bells, running water, footsteps and rolling wheels, etc. The patient hears these sounds at the same time as verbal hallucinations, the content of which is more monotonous and fixed. It is mainly seen in schizophrenia. (2) Reflex hallucination: When one sense is stimulated by reality to produce a certain sensory experience, the other sense can appear hallucinations. For example, when a patient hears the sound of a door closing, he sees the image of a person. This is seen in schizophrenia. 2. Delusion: A distorted belief, pathological reasoning and judgment based on pathology that is neither based on facts nor in accordance with the patient’s level of education, but in which the patient is convinced and cannot be convinced, nor can it be corrected by personal experience. Delusions are the most common and important symptom of thought content disorders. The content of delusions is generally often related to personal experiences, social and cultural contexts, and often reflects real-life content. For example, the content of delusions is reduced by divine power and superstition, and replaced by modern scientific instruments such as wiretaps, lasers, electric waves, artificial satellites, etc. Some delusions are close to reality, while others are absurd and bizarre. According to the structure, delusions are divided into systematic and non-systematic delusions. Systematic delusions are delusions that are connected, well-structured and logical, while non-systematic delusions are the opposite. According to the origin of delusions and the characteristics of psychological symptoms, there are two types of delusions: primary and secondary delusions. Primary delusions occur on the basis of certain experiences (e.g., delusional perceptions). These experiences suddenly convince the patient that a particular event has special significance. It is mainly seen in schizophrenia. Secondary delusions (secondarydelusion) are delusional inferences based on primary delusions or secondary to other symptoms, such as hallucinations, or exaggerated delusions in manic states, or delusions of guilt in depressive states. The common delusions in clinical practice are as follows: (1) Delusion ofreference: The patient thinks that things in the environment that are not related to him are related to him. For example, the speech and actions of others are related to him in some way, and are often intertwined with delusions of victimization. He believes that every move of people around him is a deliberate irritation; an occasional glance is unkind to him; a certain sentence on TV is intentionally insinuating him, implying him, or deliberately speaking to him. It can be seen in schizophrenia, etc. (2) Delusion of persecution (delusionofpersecution): The most common type of delusion. The patient is convinced that someone is hurting him in some way, slandering his reputation, damaging his body, or killing him. For example, they believe that they are being poisoned, stalked, watched, or conspired against. The patient may refuse to eat, press charges, run away, or act in self-defense, self-injury, or injury. It is common in schizophrenia paranoid type, paranoid psychosis. (3) Delusioninfluence: or delusions of external penetration or control of the mind or body. Patients believe that their mental activities (thinking, emotion, and volitional activities) are dominated, controlled, or manipulated by external forces; or that external forces infiltrate or stimulate their bodies, producing various uncomfortable feelings; or even that their internal activities, such as digestion, blood pressure, sleep, etc., are controlled by external forces. The patient interprets this experience as being influenced by some kind of electric waves, lasers, rays or special instruments, so it is also called delusion of physical influence. It is mostly seen in schizophrenia. (4) Delusion of grandeur: The patient believes that he or she has extraordinary talent, status and power, many inventions and wealth. For example, he thinks he is a great inventor, scientist, leader of the country, and that the wealth and power of the whole world are in his hands alone. Mostly seen in mania. There are also exaggerated identity delusions, where the patient is convinced that he is a celebrity, a rich man, a person with a title, or a descendant of a celebrity, or is related to a person of prestige. His belief that he was switched from childhood, that his parents are not his biological parents, and that his real parents are some leader or royalty, etc., can be called non-pedigree delusions. It can be seen in schizophrenia, mania, etc. (5) Delusion of sin (delusionofsin): The patient is baselessly convinced that he has committed a serious mistake, an unpardonable sin, and should be severely punished, believing that he is so guilty and deserving of death that he sits on his deathbed or refuses to eat, injures himself, commits suicide, asks for labor reform to be a new man, or asks for atonement by means of sin. Commonly seen in depressive states of affective disorders, also seen in schizophrenia. (6) Hypochondriacdelusion: The patient is convinced without any basis that he or she is suffering from a serious physical disease or an incurable disease, which cannot be corrected even through a series of detailed examinations and repeated medical verification. These delusions can be based on phantom touch or internal sensory discomfort. For example, the patient believes that “his brain is shrinking, his heart has stopped beating, his intestines are blocked, his blood is stagnant, and his internal organs are rotting”. This is often seen in menopausal psychosis and schizophrenia. (7) Nihilisticdelusion: or delusionofnegation. The patient believes that everything is destroyed, destroyed, and nothing exists anymore, even the external world and the person does not exist. The patient may believe that there is nothing left in him or her but a shell of emptiness. It is often seen in menopausal and old age mental disorders and depression. (8) Delusion ofjealousy: A pathological belief that one’s spouse is unfaithful to one’s self and is having an affair. This can be manifested as stalking, stalking, secretly checking the spouse’s underwear and bed sheets, and snooping through the spouse’s purse and mail to find evidence of the affair. It can be seen in schizophrenia and menopausal psychosis. (9) Delusion ofpregnancy: The patient is convinced that he or she is in love with a person of the opposite sex, and even if the other person sternly rejects him or her, he or she still does not doubt that the other person is testing his or her loyalty to love and continues to pester the other person. Most often seen in schizophrenia.