Perception and action in 'visual form agnosia'

A. D. Milner*, D. I. Perrett, R. S. Johnston, P. J. Benson, T. R. Jordan, D. W. Heeley, D. Bettucci, F. Mortara, R. Mutani, E. Terazzi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

452 Citations (Scopus)

Abstract

A single case study of a patient with 'visual form agnosia' is presented. A severe visual recognition deficit was accompanied by impairments in discriminating shape, reflectance, and orientation, although visual acuity and colour vision, along with tactile recognition and intelligence, were largely preserved. Neuropsychological and behavioural investigations have indicated that the patient is able to utilize visual pattern information surprisingly well for the control of hand movements during reaching, and can even read many whole words, despite being unable to make simple discriminative judgements of shape or orientation. She seems to have no awareness of shape primitives through Gestalt grouping by similarity, continuity or symmetry. It is proposed that many of these perceptual disorders might be the combined result of (1) a selective loss of the cortical elaboration of the magnocellular visual processing stream, and (2) a selective output disconnection from a central processor of visual boundaries and shape primitives in the occipital cortex.

Original languageEnglish
Pages (from-to)405-428
Number of pages24
JournalBrain
Volume114
Issue number1
DOIs
Publication statusPublished - Feb 1991

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