Elsevier

Medical Hypotheses

Volume 47, Issue 5, November 1996, Pages 347-362
Medical Hypotheses

The evolutionary biology of self-deception, laughter, dreaming and depression: Some clues from anosognosia

https://doi.org/10.1016/S0306-9877(96)90215-7Get rights and content

Abstract

Patients with right hemisphere strokes sometimes vehemently deny their paralysis. I describe three new experiments that were designed to determine the extent and depth of this denial. Curiously, when asked to perform an action with their paralyzed arm, they often employ a whole arsenal of grossly exaggerated 'Freudian defense mechanisms' to account for their failure (e.g. ‘I have arthritis’ or ‘I don't feel like moving it right now’). To explain this, I propose that, in normal individuals, the left hemisphere ordinarily deals with small, local ‘anomalies’ or discrepancies by trying to impose consistency in order to preserve the status quo. But when the anomaly exceeds threshold, a ‘devil's advocate’ in the right hemisphere intervenes and generates a paradigm shift, i.e. it results in the construction of a new model using the same data. A failure of this process in right hemisphere stroke would partially explain anosognosia. Also, our model provides a new theory for the evolutionary origin of self-deception that is different from one proposed by Trivers. And, finally, I use anosognosia as a launching-off point to speculate on a number of other aspects of human nature such as Freudian defense mechanisms, laughter, dreams and the mnemonic functions of the hippocampus.

References (47)

  • J. Cutting

    Study of anosagnosia

    J Neurol Neurosurg Psychiatr

    (1978)
  • A. Damasio

    Descartes Error

    (1994)
  • C. Darwin

    The Descent of Man

    (1871)
  • Edelman G M. The Remembered Present. Basic...
  • P. Ekman

    Unmasking the Face: A Guide to Recognizing Emotions from Facial Clues

    (1975)
  • S. Freud
  • A. Freud

    The Ego and the Mechanisms of Defense

    (1946)
  • D. Galin

    Two modes of consciousness in the two halves of the brain

  • M. Gazzaniga

    Nature's Mind

    (1992)
  • K. Goldstein

    Human Nature

    (1940)
  • M.S.A. Graziano et al.

    Coding of visual space by premotor neurons

    Science

    (1994)
  • R.L. Gregory

    Odd Perceptions

    (1991)
  • J. Heilman
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