[Prosopagnosia. Role of the right hemisphere in visual perception. (Apropos of a case after right occipital lobectomy)].

The authors describe a case of prosopagnosia which appeared a month after right occipital lobectomy. Results obtained by means of various tests devised to analyse this perception disorder have produced the following conclusions: 1) results of pairing tests which require a high level of perceptive differentiation are successful but after abnormally long delays; 2) in spite of this success, faces--even the patient's own--are not recognized; 3) this disorder extends to affect every task requiring recognition of the individual nature of a stimulus; 4) this individuality has the peculiarity of being based on visual patterns which it is impossible, or almost impossible, to express verbally; 5) the part played by defective visual representation in the brain is discussed; 6) a posterior lesion of the minor hemisphere is a prerequisite of prosopagnosia; 7) these facts, in conjunction with the findings in cases of inter-hemispheric disconnection lead one to think that the minor hemisphere, in right-handed subjects, plays a major part in the development and treatment of highly differentiated visual patterns which it is impossible, or almost impossible, to express verbally.