In 1955, the Spiral Aftereffect Test was presented as a means of diagnosing organic brain involvement.3 This procedure was earlier used by Freeman and Josey as an indicator of memory impairment.1 The test consists of rotating an Archimedes spiral figure for 30 seconds, after which the rotation is stopped. Normal subjects perceive a vivid negative after-image of apparent motion, the spiral line being seen as either expanding or contracting, depending on the direction of rotation of the spiral figure prior to being stopped. It was found that subjects with known organic brain damage, particularly those with cortical involvement, were unable to perceive or had difficulty in perceiving the distinctive after-effect.
The results of the experimental research for the diagnosis of cortical brain damage by means of the spiral after-effect were highly significant. However, 2% of the patients with organic impairment did obtain scores within the normal test limits,