Literature DB >> 18438650

Is blindsight just degraded normal vision?

Larry Weiskrantz1.   

Abstract

It is a conservative and reasonable suggestion that implicit functioning, as in blindsight, is simply a weakened, degraded form of normal functioning, especially as the parameters of vision in blindsight are themselves weakened--e.g., acuity is reduced, detection thresholds are raised, chromatic discrimination is coarser. But does this mean that maximum performance in blindsight is itself uniformly degraded? The answer is no, because there are many examples of very good performance in blindsight, in the absence of acknowledged awareness, especially if the visual parameters are chosen to be within a selective range. The question then is raised whether the parameters of blindsight vision are qualitatively similar to normal vision, or even to any manifestation of normal vision when it is uniformly degraded, for example, by threshold rises or injection of noise? Evidence is provided that blindsight vision and normal vision, even if it were degraded, are qualitatively different in certain respects. For example, there can be selective loss of colour but not of luminance contrast; visible after-images to unseen stimuli ("prime-sight") can be observed in one subject (DB); there can be super-sensitivity in the blind hemifield that is better than that of the intact hemifield; there can be a change in S-cone retinal inputs. Even when the stimulus contrast is deliberately lowered, blindsight performance itself does not degrade in parallel. Another meaning of "degraded" is that even when blindsight discriminatory or detection ability is excellent, the subject's acknowledged experience is as though the stimuli are weak and degraded to the point of extinction or near-extinction. But this is akin to the very meaning of blindsight itself, and sets the problem to be solved in neural systems terms and philosophical analysis rather than providing a conservative solution.

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Year:  2008        PMID: 18438650     DOI: 10.1007/s00221-008-1388-7

Source DB:  PubMed          Journal:  Exp Brain Res        ISSN: 0014-4819            Impact factor:   1.972


  15 in total

1.  Prime-sight in a blindsight subject.

Authors:  Lawrence Weiskrantz; Alan Cowey; Iona Hodinott-Hill
Journal:  Nat Neurosci       Date:  2002-02       Impact factor: 24.884

2.  Brain potentials associated with conscious aftereffects induced by unseen stimuli in a blindsight subject.

Authors:  L Weiskrantz; A Rao; I Hodinott-Hill; A C Nobre; A Cowey
Journal:  Proc Natl Acad Sci U S A       Date:  2003-08-19       Impact factor: 11.205

3.  The 30th Sir Frederick Bartlett lecture. Fact, artefact, and myth about blindsight.

Authors:  Alan Cowey
Journal:  Q J Exp Psychol A       Date:  2004-05

4.  Unconscious vision: new insights into the neuronal correlate of blindsight using diffusion tractography.

Authors:  Sandra E Leh; Heidi Johansen-Berg; Alain Ptito
Journal:  Brain       Date:  2006-05-19       Impact factor: 13.501

5.  Parameters affecting conscious versus unconscious visual discrimination with damage to the visual cortex (V1).

Authors:  L Weiskrantz; J L Barbur; A Sahraie
Journal:  Proc Natl Acad Sci U S A       Date:  1995-06-20       Impact factor: 11.205

6.  Pattern of neuronal activity associated with conscious and unconscious processing of visual signals.

Authors:  A Sahraie; L Weiskrantz; J L Barbur; A Simmons; S C Williams; M J Brammer
Journal:  Proc Natl Acad Sci U S A       Date:  1997-08-19       Impact factor: 11.205

7.  Is blindsight like normal, near-threshold vision?

Authors:  P Azzopardi; A Cowey
Journal:  Proc Natl Acad Sci U S A       Date:  1997-12-09       Impact factor: 11.205

8.  Absence of S-cone input in human blindsight following hemispherectomy.

Authors:  Sandra E Leh; Kathy T Mullen; Alain Ptito
Journal:  Eur J Neurosci       Date:  2006-11       Impact factor: 3.386

9.  Spatial summation across the vertical meridian in hemianopics: a test of blindsight.

Authors:  C A Marzi; G Tassinari; S Aglioti; L Lutzemberger
Journal:  Neuropsychologia       Date:  1986       Impact factor: 3.139

10.  Color contrast processing in human striate cortex.

Authors:  R W Kentridge; C A Heywood; L Weiskrantz
Journal:  Proc Natl Acad Sci U S A       Date:  2007-09-06       Impact factor: 11.205

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  19 in total

Review 1.  Visual experience and blindsight: a methodological review.

Authors:  Morten Overgaard
Journal:  Exp Brain Res       Date:  2011-02-15       Impact factor: 1.972

2.  Endogenous visuospatial attention increases visual awareness independent of visual discrimination sensitivity.

Authors:  Marine Vernet; Shruti Japee; Savannah Lokey; Sara Ahmed; Valentinos Zachariou; Leslie G Ungerleider
Journal:  Neuropsychologia       Date:  2017-08-12       Impact factor: 3.139

Review 3.  Neural correlates of consciousness: progress and problems.

Authors:  Christof Koch; Marcello Massimini; Melanie Boly; Giulio Tononi
Journal:  Nat Rev Neurosci       Date:  2016-05       Impact factor: 34.870

4.  Distinct representation and distribution of visual information by specific cell types in mouse superficial superior colliculus.

Authors:  Samuel D Gale; Gabe J Murphy
Journal:  J Neurosci       Date:  2014-10-01       Impact factor: 6.167

5.  Preliminary report on the association between pulvinar volume and the ability to detect backward-masked facial features.

Authors:  M Justin Kim; Alison M Mattek; Daisy A Burr; Paul J Whalen
Journal:  Neuropsychologia       Date:  2017-10-31       Impact factor: 3.139

6.  Morphological evidence for multiple distinct channels of corticogeniculate feedback originating in mid-level extrastriate visual areas of the ferret.

Authors:  Matthew Adusei; J Michael Hasse; Farran Briggs
Journal:  Brain Struct Funct       Date:  2021-10-12       Impact factor: 3.748

7.  Disentangling conscious and unconscious processing: a subjective trial-based assessment approach.

Authors:  Eva Van den Bussche; Astrid Vermeiren; Kobe Desender; Wim Gevers; Gethin Hughes; Tom Verguts; Bert Reynvoet
Journal:  Front Hum Neurosci       Date:  2013-11-18       Impact factor: 3.169

8.  Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.

Authors:  Christopher P G Allen; Benjamin T Dunkley; Suresh D Muthukumaraswamy; Richard Edden; C John Evans; Petroc Sumner; Krish D Singh; Christopher D Chambers
Journal:  PLoS One       Date:  2014-06-23       Impact factor: 3.240

9.  Action without awareness: reaching to an object you do not remember seeing.

Authors:  Matthew Heath; Anika Maraj; Bryan Godbolt; Gordon Binsted
Journal:  PLoS One       Date:  2008-10-27       Impact factor: 3.240

10.  Brain-stimulation induced blindsight: unconscious vision or response bias?

Authors:  David A Lloyd; Arman Abrahamyan; Justin A Harris
Journal:  PLoS One       Date:  2013-12-06       Impact factor: 3.240

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