Form discrimination in a case of blindsight.

Full Abstract

DB, the first extensively tested blindsight case, has demonstrated the ability to detect and discriminate a range of visual stimuli presented within his perimetrically blind visual field [Weiskrantz L. (1986). Blindsight:
A case study and implications. Oxford:
Oxford University Press]. After initial reports of basic form discrimination (Weiskrantz, 1986), it later emerged that this ability to discriminate single stimuli presented to the blind field was probably based on the discrimination of orientation cues [Weiskrantz, L. (1987). Residual vision in a scotoma. A follow-up study of 'form' discrimination. Brain, 110, 77-92]. Even so, DB found it impossible to make a 'same/different' discrimination for pairs of stimuli in the blind field (Weiskrantz, 1986). In the current study, DB's discrimination and identification of stimuli on the basis of their form was tested (in 2AFC and FR paradigms). We have demonstrated that DB could successfully identify outline low contrast images of objects, make successful 'same/different' discriminations for pairs of stimuli presented in his blind field and identify complex images (digital photographs) presented entirely within his cortically blind field. The results are discussed in relation to the issues of likely neuronal mediation, the potential for improvement in cases of blindsight and the potential relevance of these findings in relation to theories of normal visual perception.

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Author information

Author/s: Trevethan, Ceri T (CT); Sahraie, Arash (A); Weiskrantz, Larry (L);

Affiliation: Vision Research Laboratories, School of Psychology, William Guild Building, University of Aberdeen, Aberdeen, AB24 2UB Scotland, UK. c.trevethan(-atsign-)abdn.ac.uk

Journal and publication information

Publication Type: Case Reports; Journal Article; Research Support, Non-U.S. Gov't

Journal: Neuropsychologia (Neuropsychologia), published in England. (Language: eng)

Reference: 2007-May; vol 45 (issue 9) : pp 2092-103

Dates: Created 2007/05/02; Completed 2007/07/18;

PMID: 17368683, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Aged
Case-Control Studies
Discrimination (Psychology) - physiology
Follow-Up Studies
Form Perception - physiology
Hemianopsia - physiopathology

Humans
Male
Middle Aged
Pattern Recognition, Visual - physiology
Photic Stimulation - methods
Visual Fields - physiology

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