Anton-Babinski syndrome

Anton-Babinski syndrome, more frequently known as Anton's blindness, is a rare symptom of brain damage occurring in the occipital lobe. People who suffer from it are "cortically blind," but affirm, often quite adamantly and in the face of clear evidence of their blindness, that they are capable of seeing. Failure to see is dismissed by the sufferer through confabulation. It is mostly seen following a stroke, but may also be seen after head injury. It's believed that the cause is damage to two areas; the portion of the brain responsible for eyesight, and the portion responsible for detecting the presence of vision.

This condition is named after Gabriel Anton and Joseph Babinski. It is well described by the neurologist Macdonald Critchley:

The sudden development of bilateral occipital dysfunction is likely to produce transient physical and psychical effects in which mental confusion may be prominent. It may be some days before the relatives, or the nursing staff, tumble to the fact that the patient has actually become sightless. This is not only because the patient ordinarily does not volunteer the information that he has become blind, but he furthermore misleads his entourage by behaving and talking as though he were sighted. Attention is aroused however when the patient is found to collide with pieces of furniture, to fall over objects, and to experience difficulty in finding his way around. He may try to walk through a wall or through a closed door on his way from one room to another. Suspicion is still further alerted when he begins to describe people and objects around him which, as a matter of fact, are not there at all. Thus we have the twin symptoms of anosognosia (or lack of awareness of defect) and confabulation, the latter affecting both speech and behaviour. ("Modes of reaction to central blindness", in The Divine Banquet of the Brain, Raven, New York, 1979, p. 156)

The syndrome may be conceptualised ideally as the converse of blindsight: a syndrome in which part of the visual field is experienced as completely inoperative, but some reliable perception does in fact occur.