A 35-year-old lady complains of changes in the shape of objects perceived. She is having difficulties in perceiving the symmetry of objects. This symptom is called:
A. A perceptual error associated with changes in shape of objects, especially with loss of symmetry, is called dysmegalopsia. The objects can shrink in size (micropsia) or enlarge (macropsia). These are usually organic and could be related to ictal (parietal) or ocular pathology (accommodation errors – paralysed accommodation can cause micropsia). They are also rarely seen in acute schizophrenia. Hallucinogens (e.g. mescaline) can also change the colour of perceived objects or make components of an object (e.g. body parts) be seen detached in space.
A 12-year-old boy, at a school anniversary celebration, vividly describes what martians may look like.
Which of the following is true about this imagery? The imagery is:
B. Imagery is not a perception because there is no stimulus involved and no object perceived; it is essentially a fantasy. Imagery refers to images produced voluntarily with complete insight that they are a mental phenomena and not of external origin. Imageries lack the ‘objective’ quality of hallucinations and normal sense perceptions.
An 8-year-old boy is frightened to be alone at home. He starts seeing monsters out of wind moving through window curtains.
Which of the following symptoms is he experiencing?
D. There are three major types of illusions: in affect illusion the prevailing emotional state leads to misperceptions, for example a depressed patient reading ‘deed’ as ‘dead’, a boy frightened of the dark seeing monsters from innocuous shadows. Pareidolia refers to perceiving formed objects from ambiguous stimuli, for example seeing cars in the clouds. It is common in delirium, especially in children. They are often playful – not characteristic of any psychotic illness. Completion illusion is due to inattention; stimulus that does not form a complete object might be perceived to be complete, for example CCOK is read as COOK. Eidetic imagery is considered to be a special ability of memory wherein visual images are drawn from memory accurately, at will and described as if being perceived currently. This is not a perceptual distortion but closely linked to mental imagery and it is often noted in children.
A 19-year-old man sees his new girlfriend’s face from the shapes of clouds.
This perception will:
A. Pareidolia refers to perceiving formed objects from ambiguous stimuli, for example seeing faces in a fi re or hidden messages when records are played in reverse. It is coloured by prevailing emotion and not entirely due to inattention or affective change; fantasy and imagery play a part in addition to actual sense perception. On paying extra effort the object intensifies and does not disappear. Pareidolia is common in febrile delirium, especially in children, and also in hallucinogen use. They are under voluntary control and often playful. Occurrence of pareidolia is not characteristic of any psychotic illness.
A 35-year-old lady reports hearing voices in her head.
Which of the following differences between hallucination and pseudohallucination is true?
D. Hallucinations have several important qualities which are essential in differentiating them from other mental phenomena. Hallucinations take place at the same time and in the same space as other perceptions, for example ‘an angel is standing in the corner of my room’. This is different from fantasy or imagery which takes place in a subjective space. They are experienced as sensations – not as thoughts – in contrast to obsessional images. The percept has all the qualities of a real world object , that is a patient when hallucinating believes that the percept can be experienced in other modalities too, like a real object which can be seen, felt, smelt, and heard. Pseudohallucinations are defined variously. The term is used to describe hallucination-like experiences with retained insight (so it is not sought in other modalities of perception). It is also used to describe hallucination-like experiences that take place in a subjective space, for example ‘a voice inside my head’.
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