Schemas reveal spatial relations to a patient with simultanagnosia.

Maps, graphs, and diagrams use simplified graphic forms, like lines and blobs, to represent basic spatial relations, like boundaries and enclosures. A schema is an iconic representation where perceptual detail has been abstracted away from reality in order to provide a more flexible structure for cognition. Unlike truly symbolic representations of spatial relations (i.e., prepositions) a schema preserves some analog spatial qualities of the relation it stands in for. We tested the efficacy of schemas in facilitating the perception and comprehension of spatial relations in a patient with bilateral occipitoparietal damage and resulting simultanagnosia. Patient E.E. performed six matching tasks involving WORDS (in, on, above, below), photographic PICTURES of objects, and/or SCHEMAS depicting the same spatial relations. E.E. was instructed to match a single spatial relation to a corresponding image from an array of four choices. On the two tasks that did not include matching to or from schemas, E.E. performed at chance levels. On tasks with schemas, performance was significantly better, indicating that schematic representations make spatial relations visible in a manner that symbols and complex images do not. The results provide general insight as to how schemas facilitate spatial reasoning when used in graphic depictions, and how such theoretically intermediate representational structures could serve to link perceptual and verbal representations of spatial relations in the brain.