- Also known as left size distortion. The term hyperschematia comes from the Greek words huper (to exceed a certain boundary) and schèma (form, scheme, topographic map). It translates roughly as 'overly detailed mapping of space'. The term hyperschématie was introduced in or shortly before 1905 by the French neurologist Pierre Bonnier (1861-1918) to denote a variant of " aschematia characterized by an exaggeration of the space occupied by some part of the body. Today the term is used to denote a left (i.e. con-tralesional) expansion of object representations due to a lesion to the right parietal lobe. Because of its subjective nature, hyperschematia cannot be observed directly in affected individuals. However, the condition can be inferred from drawings made by these individuals. In these drawings, the left side of a clock is characteristically enlarged and the petals on the left side of a daisy tend to be both larger and more numerous than those on the right. Hyperschematia is considered a productive, subconscious manifestation of neglect. It is usually classified as a "body schema illusion. Although phenomenologically there is some overlap between hyperschematia and " hemimicropsia, the two conditions differ in several respects: hemimicropsia may affect either of the spatial hemifields, individuals with hemimi-cropsia tend to be aware of their condition, and they perceive objects within the contralesional hemifield as being smaller and/or distorted in size. The term hyperschematia was used by Bonnier in opposition to the terms "hyposchematia and " paraschematia.ReferencesBonnier, P. (1905). L'aschématie. Revue Neurologique, 13, 605-609.Rode, G., Michel, C., Rossetti, Y., Boisson, D., Vallar, G. (2006). Left size distortion (hyper-schematia) after right brain damage. Neurology, 67, 1801-1808.
Dictionary of Hallucinations. J.D. Blom. 2010.