The 20 types of hallucinations (and their characteristics)

The brain is our command center. This organ, the nucleus of the central nervous system, is in charge of processing internal and external information captured by our senses and generating responses that control our physiology. After all, everything we experience is born in the brain. It is he who determines what we feel and what we see. Everything is created by the mind.

And it's no secret that our minds can play tricks on us. It is perfectly normal that we forget things, that our memories alter over time or that we think we see things that, in reality, are not there. But all these "tricks" of the mind reach their maximum expression with the so famous, but at the same time so unknown, hallucinations.

Hallucinations are phenomena that consist of perceiving sounds, sights or smells that, although they seem real, are not.. Hallucinations, behind which there are many different causes and triggers, are sensory perceptions of an external stimulus that, although it does not exist since it is created internally by our mind, is considered and interpreted by our brain as real.

Thus, in today's article and with the intention of answering all the questions you may have about this concept, we are going to analyze the clinical bases of hallucinations and present a classification of them according to the sensory modality and the way in which they the one that appear. So let's see what kinds of hallucinations exist.

How are hallucinations classified?

Hallucinations are sensory perceptions that do not correspond to any real external stimulus. In other words, a hallucination consists of seeing, smelling or hearing things that, although they seem real, are not. In other words, they are perceptions of a physical stimulus that does not exist, but experiencing that sensation as if it were real.

In this context, hallucinations are considered as pseudoperceptions that can occur on any sensory modality, something that, as we will see, determines their classification. Listening to sounds that do not exist, perceiving smells, seeing beings, hearing voices, experiencing sensations in the body, visualizing objects that are not there ... A hallucination can manifest itself in many different ways.

And as we have said, the causes behind these hallucinations are very varied, ranging from dementia or delirium to the influence of hallucinogenic drugs, going through withdrawal symptoms from other non-hallucinogenic drugs, suffering from epilepsy, having very high fever, suffering from narcolepsy, suffering from sensory problems, suffering from psychiatric diseases ( especially schizophrenia) or develop brain tumors, brain lesions, among others.

Be that as it may, in any case of a person who begins to hallucinate, taking into account that this situation can quickly lead to complications that lead to clinical emergencies, it is important that the person is not alone and is immediately accompanied to the doctor for evaluation.

But since not all hallucinations are the same, next we will see in what ways they can manifest themselves. Let's see, then, what are the characteristics of the different types of hallucinations, classified according to both the sensory modality and the way in which they appear.

1. Auditory hallucinations

Auditory hallucinations are the most frequent and consist of hearing sounds or hearing voices that do not exist. Thus, the sensory modality on which it acts is hearing. They are usually experienced in schizophrenia, consisting of whispers, whispers, or clearly identified voices of negative and threatening content.

2. Visual hallucinations

Visual hallucinations are those that consist of seeing things that do not exist. The sensory modality on which it acts is sight, perceiving images of objects, beings, lights, people or entities that are not there. They are common as a symptom of dementia, alcohol withdrawal, the use of certain medications, and even migraines.

3. Olfactory hallucinations

Olfactory hallucinations are those that consist of experiencing smells that don't exist. It is a strange type of hallucination that acts on the sense of smell and makes us smell something that is not there, generally being unpleasant, such as the smell of feces or vomit. They are usually associated with epilepsy or lesions in the brain regions that control the sense of smell.

4. Taste hallucinations

Taste hallucinations, which tend to go hand in hand with olfactory ones, are those in which we experience flavors without eating anything. They tend to appear in patients with schizophrenia or depression and the sensory modality on which it acts is taste. Savor things without having anything in your mouth. This is the basis for a taste hallucination.

5. Tactile hallucinations

Tactile hallucinations are those that consist of feel sensations on the skin of elements that are not there, generally based on perceiving as if there were insects moving through the body. The sensory modality on which it acts is touch and they are usually the result of alcoholism or, more commonly, the effects of drugs such as amphetamines or cocaine. Also known as haptic hallucinations, they are active skin sensations (feeling that we touch things) or passive (feeling that something touches us).

6. Somatic hallucinations

Somatic hallucinations are those that consist of alterations in the way we perceive the interior of our body. Based on interference with proprioception, these hallucinations make people who have them feel like they are missing organs, that they have metallic organs, or that their internal organs move strangely or are in the wrong places.

7. Kinesic hallucinations

Kinesic hallucinations, also known as kinesthetic hallucinations, are those that consist of alterations in the way we perceive body movement. It is a hallucination that affects the perception of our body's movement, being common with the consumption of hallucinogenic drugs and as a symptom of Parkinson's disease.

8. Paresthetic hallucinations

Paresthetic hallucinations, also known as paresthesias, is a disorder of tactile sensitivity that manifests itself with abnormal irritation or tingling sensations on the skin without any physical stimulus that has awakened them. They usually appear after the consumption of drugs such as cocaine or as a symptom of diseases such as Wernicke-Korsakoff syndrome, a type of encephalopathy due to vitamin B1 deficiency.

9. Reflex hallucinations

Having already seen the different kinds of hallucinations according to the sensory modality on which they act, it is time to go on to analyze them according to their mode of appearance. Reflex hallucinations are those in which a real stimulus triggers the experimentation of a false stimulus of different sensory modalities. For example, hearing a baby crying (auditory modality) triggers a hallucination of smelling something unpleasant that does not exist (olfactory modality).

10. Functional hallucinations

In contrast, functional hallucinations are those in which a real stimulus triggers the experimentation of a false stimulus but of the same sensory modality. Continuing with the example, hearing a baby crying (auditory modality) could trigger a hallucination of hearing a certain melody (also auditory modality).

11. Negative hallucinations

Negative hallucinations are a particular case, because on this occasion it is not that we experience things that are not there, but quite the opposite. They are hallucinations that consist of not perceiving something that is really there.

12. Autoscopic hallucinations

Autoscopic hallucinations, also known as autoscopies, are sensations or experiences in which the person sees his own body from an external perspective, as if observing himself from outside his body.

13. Negative autoscopic hallucinations

Autoscopic negative hallucinations combine the above two types of hallucinations It is a strange experience in which the person, when he goes to look in the mirror, does not see himself.

14. Hypnagogic hallucinations

Hypnagogic hallucinations are those that are not linked to any neurological disorder, but rather occur in the transition between wakefulness and deep sleep. In this phase, the person can experience hallucinations of any sensory modality. It has been observed that suffering from anxiety makes the person more prone to present them.

15. Extracampine hallucinations

Extracampine hallucinations are a type of visual modality hallucination in which we see things that are not within our visual field. That is, we see someone in front of us who, in reality, is behind us.

16. Pseudo-hallucinations

Psuedohallucinations are those in which, although the person experiences a hallucination in any sensory modality, this is aware at all times that it is not real. Thus, we do not take as true what we are experiencing.

17. Physiological hallucinations

Physiological hallucinations are those in which there is no underlying neurological disorder, being rather natural consequences of brain mechanisms. It occurs not only, as we have seen, in hypnagogic hallucinations, but also in conditions of hypothermia, extreme dehydration, starvation, hyperthermia, etc.

18. Psychiatric hallucinations

Psychiatric hallucinations are all those hallucinations that make up the symptoms of a mental disorder such as schizophrenia. They are psychiatric pathologies that, among their clinical signs, are these hallucinations.

19. Organic hallucinations

Organic hallucinations are those that appear due to non-mental illnesses, but rather to somatic pathologies, such as brain injuries, development of tumors in the brain, effect of hallucinogenic drugs, withdrawal syndrome, epilepsy, etc.

20. Environmental hallucinations

And we end with environmental hallucinations, those that are experienced by exposure to highly stressful external stimuli for the brain, as for example in the event of a kidnapping, social isolation, sensitive overload, etc.