Encyclopedia of Clinical Neuropsychology

2018 Edition
| Editors: Jeffrey S. Kreutzer, John DeLuca, Bruce Caplan

Ahylognosia

  • John E. MendozaEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-3-319-57111-9_698

Definition

Inability to determine by touch alone certain physical properties of an object such as its texture, density (weight), or resistance to pressure, with difficulties in perceiving size or shape is referred to as amorphognosia. While perhaps seeming a bit artificial, according to Bauer and Demery (2003), the distinction between ahylognosia and amorphognosia apparently traces back to 1935 when a French neurologist, Delay, divided astereognosis into two subtypes of deficits: amorphognosia, which was defined as a difficulty in recognizing the size or shape of an object by touch, and ahylognosia, which was described as a failure to differentiate the “molecular qualities” of an object, such as its density, weight, thermal conductivity, or roughness. Delay also defined a third type of astereognosis, tactile asymboly, which was characterized as the inability to identify an object by touch in the absence of amorphognosia and ahylognosia. These same distinctions were followed by...

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References and Readings

  1. 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
  2. Critchley, M. (1969). The parietal lobes. New York: Hafner Publishing Co.Google Scholar
  3. Delay, J. (1935). Les astereognosis. Pathologie due Toucher, Clinque, Physiologie, Topographie. Paris: Masson.Google Scholar
  4. Hecaen, H., & Albert, M. L. (1978). Chapter 6, Disorders of somesthesis and somatognosis. In Human neuropsychology. New York: Wiley.Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Psychiatry and NeuroscienceTulane Medical School and SE Louisiana Veterans Healthcare SystemNew OrleansUSA