Psychopathology of perception. Perceptual deceptions or errors (III/III)

DECEPTIONS OR PERCEPTUAL ERRORS

EIn this last section we briefly describe the most characteristic psychopathological activity in psychiatry; although many of the phenomena described here can occur in normal subjects who are exposed to stressful or emotionally impactful situations.

CONTENT

1. Delusions
2. Hallucinations
3. Pseudo-hallucinations

DELUSIONS

These are distorted perceptions. The real stimulus exists, although the individual misinterprets it. They were described by Jasper. They are usually of three types:

• Illusions due to inattention, also called fables. Due to an attentional lapse, the subject does not perceive the stimulus in its entirety, finding themselves needing to "fill in" the missing elements. This occurs quite frequently, even in normal situations, when we recall a memory and "fill in" what we don't remember with our own fabrications.
• Emotional illusions (Jaspers), also called catathymic By Serráis (Fernando Serráis. Psychopathology. EUNSA Publishing House. Pamplona, ​​2016). These are the ones that appear due to an intense emotional state, such as fear. Here, the subject misinterprets reality by projecting their own images onto it. For example, when we project human figures onto trees in the dark.
• Pareidolia (Kahlbaum). It is the projection of vaguely structured mental images created by the individual onto real objects. This phenomenon also includes when we interpret words from noises without linguistic meaning. The Rorschach test is based precisely on this perceptual phenomenon. Mirages (seeing faces in the clouds, an oasis that doesn't exist, for example) are forms of mirages. They are considered a variant of pareidolia.

HALLUCINATIONS

 They are usually defined as perceptions without an object. For Luis Martín Santos, “when a representation has the qualities of perception, we are dealing with a hallucination.” These are then corporeal images, located in objective external space, with a defined and complete design, sensory freshness, constant, independent of the will, and with a positive judgment of reality. For the subject, they are real.¹For Jaspers, hallucinations must meet the following characteristics: They must be situated in the real world; clearly delimited; independent of the will and constant; they are sensorially complete and current (Serráis).

They can be classified according to their complexity: Elemental (noises) and complex (You can hear complete dialogues, music, etc.). They are most commonly classified according to the senses: Visual, auditory, kinesthetic, gustatory, tactile, muscular, kinesthetic.

There are authors who refer to certain perceptual phenomena as hallucinations. They do not fully meet the requirements that are required for hallucinations. They are the following:

•   Functional hallucinations: When normal sensory perceptions in an organ cause hallucinations, these hallucinations disappear when the stimulus ceases. For example, a patient who hears voices when they perceive the noise of an airplane. The voices disappear when the airplane stops being heard (real case). The patient hears the noise of the airplane and the voices; that is, they do not merge.
• Hypnagogic hallucinations: They appear at the time of falling asleep and are especially auditory and visual.
• Hypnopompic hallucinations: At the moment of waking up.
• Hysterical hallucinations: These are phenomena similar to those that occur in hypnosis. They are images that the subject imposes upon themselves and are usually visual.
• Obsessive hallucinations: The contents of fixed ideas become visible to the subject everywhere.
• Negative hallucinations: It consists of the subject ceasing to perceive certain aspects of reality and is usually present in hysteria.
• Reflex hallucinations: Hallucinations in one sensory field cause hallucinatory activity to appear in another.
• Autoscopic hallucinations: Internal: when the subject sees themselves within themselves. External: The subject sees their own image outside of their body.
• Ecmnesiac hallucinationsThe subject hallucinates images that happened in the past.
• Pseudo-hallucinations

To Kandinsky and Jaspers, cited by López Sánchez,²  These are not true hallucinatory activity because they do not meet all the characteristics of hallucinations. Pseudo-hallucinations:

• They lack corporeality. They are imaginary. They are images.
• They occur in the internal subjective space
• They are presented with a specific design.
• They offer sensory freshness.
•  They are constant.
• They are independent of the will.
• Positive judgment of reality

Depending on the authors, they also include the hallucinosis. These are perceptions without an object, which the subject is able to criticize at the time they occur; that is, there is a negative judgment of reality. They are very common in Alcohol Withdrawal Syndrome.

1. Martín Santos, L: Dilthey, Jaspers and the understanding of the mentally ill. Ed. Paz Montalvo, Madrid (1955) [↩]
2. López Sánchez, JM et al. Compendium of Psychopathology. Ed. Circle of Psychopathological Studies. 2nd Edition. Granada (1982) [↩]