The human being constantly perceives the reality that surrounds him, obtaining information from the environment through the different senses to later integrate the various data and process them in different brain nuclei.
However, sometimes alterations occur that cause objects and stimuli not to be perceived correctly. This is the case of perceptual cleavage .
Perceptual cleavage as alteration of perception
We understand by perceptual cleavage that type of alteration of perception in which the information referring to the stimuli is not perceived in an integrated manner. This can occur with information from different sensory modalities but generally the concept of perceptual cleavage tends to refer to the separation of perceptual elements captured by the same sense, the most common case being that of the disintegration of visual information.
It is important to note that the problem does not occur at the visual level or in the sensory organs , which are fully functional. And although it is an alteration of perception, we are not dealing with a hallucination either: the perceived stimuli are always real. The problem in question is that although we capture information correctly we are not able to integrate it, which generates two competing perceptions.
In this way, before the perceptive division we see the stimulus disintegrated appreciating separately aspects that we should see as a whole, such as the form of the objects and their content or separating the color and the form. We would not see a red apple, but on the one hand the colour red and on the other an apple.
Types of perceptual cleavage
There is no single type of perceptual cleavage . In general, we can consider that, with regard to the type of excision that occurs in the same sensory mode and specifically in that of sight, there are two main types of perceptual excision: morpholysis and metacromy. In addition, it is possible that perceptual cleavage occurs between different senses.
Morpholysis is the perceptual cleavage that is only at the level of form . We are unable to gather the information of the form of the objects from their content. It is possible, for example, that we see someone’s face separated from their body.
As for metacromies, they refer to those perceptive divisions in which we perceive colour and shape separately . For example, we see them separately or the color exceeds the shape (as if we were going off the line when painting an object), or colors that do not correspond to the real ones.
3. Disintegration of information from different sensory modes
This is usually the dissociation between sight and hearing, although other senses may also fall into this category. Thus, what we hear and what we see is perceived separately, as if it came from two different stimuli. For example, we are unable to relate the voice to the movement of the lips of the person in front of us. It could also happen with sight and touch, for example.
It is very frequent that morpholysis and metacromy appear in the context of a psychotic break . Likewise, the hyperstimulation of epilepsy itself can also generate perceptual excision phenomena. It is not uncommon for it to appear in the presence of intoxication or consumption of substances such as psychodisleptics. Another context in which perceptual excision may occur is in the presence of brain damage caused by traumatic brain injury and stroke, or by the compression of certain nerve pathways in cases of brain tumours, for example.
The most likely cause of this type of phenomena is found in the malfunctioning of some of the relay nuclei or nerve pathways where the information from the different perceptual pathways is processed and integrated, both in the same direction and from the whole of the external information. This means that different elements of the same perception are perceived separately.
Perceptual excision is not a disorder per se, but a symptom. As such, its treatment will depend largely on the type of disorder that generates it. For example, drugs can be prescribed that cancel the effect of the substances taken that generate the alteration, or neuroleptics that can slow and stop the psychotic break and reduce the possibility of new ones arising. In some cases it may be advisable to perform occupational therapy and rehabilitation that can help restore the normal functioning of the nerve connections.
However, what will always be advisable is to provide the patient with information about what is happening , given that this type of alteration can involve a great level of anguish and concern.
Belloch, A.; Sandín, B. and Ramos, F. (2002). Manual of Psychopathology, Vol. McGraw-Hill. Madrid.