Literally, a loss of previous color knowledge.
In pure color agnosia, patients have difficulty naming or pointing to named colors, despite relatively preserved color perception (i.e., retaining the ability to match colors or to identify the numbers on the Ishihara plates). They also have difficulty matching colors, either verbally or visually, to familiar colored objects (e.g., identifying the color normally associated with cherries, lettuce, or bananas).
Relatively rare, pure color agnosia must be distinguished from other disturbances of color perception and color naming (color anomia). In color blindness, the individual is unable to perceive or distinguish either certain colors or possibly all color. In the latter case, the world is seen in shades of black and white. While color blindness is usually congenital, it can also be acquired, a condition known as central achromatopsia. The latter is a perceptual deficit thought to result from lesions in the...
References and Readings
- Bauer, R. M., & Demery, J. A. (2003). Agnosia. In K. Heilman & E. Valenstein (Eds.), Clinical neuropsychology (4th ed., pp. 236–295). New York: Oxford University Press.Google Scholar
- Tranel, D. (2003). Disorders of color processing. In T. E. Feinberg & M. J. Farah (Eds.), Behavioral neurology and neuropsychology (pp. 243–256). New York: McGraw-Hill.Google Scholar