ABNORMALITIES OF PERCEPTION

• Hyperaesthesia: Increased intensity of sensations, seen in intense emotions and hypochondriacal personalities
• Illusions: Misperceptions or misinterpretations of real external sensory stimuli: e.g. Shadows may be misperceived as frightening figures.
• Hallucinations: Perception in the absence of real external stimuli; experienced as true perception coming from the external word (not within the mind). e.g. hearing a voice of someone when actually nobody is speaking within the hearing distance.
  • Auditory hallucinations (voice, sound, noise).
    • Second-person hallucinations: voice speaking to the person addressing him as “you”.
    • Third-person hallucinations: voice talking about the person as “he” or “she”:
    • Thought echo: hearing one’s own thoughts spoken aloud.
  • Visual hallucinations (images/sights)
  • Olfactory hallucinations (smell/odour)
  • Gustatory hallucinations (taste)
  • Tactile hallucinations (touch/surface sensations)
  • Somatic hallucinations (visceral and other internal sensations).
• Imperative hallucination: voices giving instructions to patients, who may or may not feel obliged to carry them out.
• ‘Thought echo’ (Gedankenlautwerden): hearing one’s own thoughts being spoken aloud; the voice may come from inside or outside the head.
• Running commentary hallucinations: are usually abusive and often talk about sexual topics.
• Scenic hallucinations:   hallucinations in which whole scenes are hallucinated like a cinema film; more common in psychiatric disorders associated with epilepsy.
• Lilliputian hallucinations:  micropsia affects the visual hallucinations, so the pt. sees tiny people.
• ‘Formication’: a feeling that animals are crawling over the body; not uncommon in acute organic states.
• ‘Cocaine bug’: formication occurring with delusions of persecution; in cocaine psychosis.
• Functional hallucinations: a stimulus causes the hallucination, but it is experienced as well as the hallucination. Seen in chronic schizophrenia
• Reflex hallucinations: a stimulus in one sensory field produces a hallucination in another.
• Extracampine hallucinations:  a hallucination which is outside the limits of the sensory field.
• Autoscopy (phantom mirror image): the pt. sees himself and knows that it is he. Seen in normal subjects when they are depressed or emotionally disturbed.
• ‘Negative autoscopy’:  the pt. looks in the mirror and sees no image; in organic states.
• Internal autoscopy: the subject sees his own internal organs.
• Pseudo-Hallucinations: Sensory deceptions perceived as emanating from within the mind.
• Hypnagogic hallucinations: hallucinations when falling asleep
• Hypnopompic hallucinations: hallucinations when waking from sleep

References

1. Psychiatry, Third Edition. Edited by Allan Tasman, Jerald Kay, Jeffrey A. Lieberman, Michael B. First and Mario Maj. John Wiley & Sons, Ltd, 2008.
2. Sims, A. Symptoms in the Mind: An Introduction to Descriptive Psychopathology (3rd ed). Elsevier, 2002.
3. Fish, F. Clinical Psychopathology, Signs and Symptoms in Psychiatry. Bristol: J. Wright & Sons. 1967.

Posted in: Mental Health Nursing,Psychology