Ramachandran, Vilayanur S.; Levi, L.; Stone, L.; Rogers-Ramachandran, D.; and
Illusions of body image: What they reveal about human nature
The mind-brain continuum: Sensory processes.
Edited by Rodolfo Riascos Llinas, Patricia Smith Churchland, et al.
Cambridge, MA: MIT Press, 1996. 29-60 of 315 pp.
The authors aim to bring the syndromes phantom limbs and anosognosia-somatoparaphrenia into the mainstream of modern neuroscience. They argue that far from being mere oddities, these illustrate certain important principles underlying the functional organization of the normal human brain.
The ideas proposed have much more in common with biologically based theories of cognition and perception than it does with the central tenets of classical artificial intelligence.
The authors discuss phantom limbs, including the apparent amputation of a phantom limb using virtual reality, a new treatment for phantom limb pain, touching the phantom and the central condition. They go into the surreal logic of anosognosia and develop a new biological theory of self-deception. This questions R. Trivers's suggestion that deception is more effective if it is accompanied by self-deception. They examine the implications for mnemonic functions, multiple personalities, fugue states, and supernumerary phantoms. Describe experiments on anosognosia, such as the virtual reality box, cocktail glasses on a tray, unimanual vs. bimanual tasks, and repressed memories in anosognosia. Finally, they outline a theory of dreams as nature's own virtual reality and a biological hypothesis of humor and laughter.
Ramachandran, V. S and Diane Rogers-Ramachandran
Denial of disabilities in anosognosia.
Nature 382. 6591 (August 1996): 501.
Studied three female right-hemisphere stroke patients (aged 77 and 78 yrs old) with left-sided hemiplegia. While all three Subjects were mentally lucid, they all denied their paralysis. Two Subjects also refused to acknowledge the paralysis of a fourth patient who was in a wheelchair next to them. Their failure to acknowledge paralysis was not due to body-part confusion or to general confusion about limb movements.
Ramachandran, V. S.
Anosognosia in parietal lobe syndrome.
Consciousness & Cognition 4. 1(1995 Mar): 22-51.
Devised three tests to explore why patients with right parietal lesions often deny their paralysis. Four elderly patients (aged 65-78 yrs) were given a choice between a bimanual task vs a unimanual one. They chose the former on 17 of 18 trials and showed no frustration or learning despite repeated failed attempts, indicating they have no tacit knowledge of paralysis. Second, a "virtual reality box" was used to convey the optical illusion to one subject that she was moving her paralyzed left hand up and down to the rhythm of a metronome, and yet she showed no sign of surprise. Third, another subject's left ear canal was irrigated with cold water, a procedure that allowed her repressed memory of the paralysis to emerge. It is suggested that these subjects use a variety of grossly exaggerated Freudian defense mechanisms to account for their paralysis. A new framework is proposed for linking seemingly unrelated phenomena such as anosognosia, REM, amnesia, and laughter.
Maintained by Francis F. Steen, Communication Studies, University of California Los Angeles