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Conscious Cogn. 2015 Mar;32:6-14. doi: 10.1016/j.concog.2014.07.010. Epub 2014 Aug 11.

Speeded manual responses to unseen visual stimuli in hemianopic patients: what kind of blindsight?

Author information

1
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy; Department of Psychology, University of Torino, Torino, Italy; Cognitive and Affective Neuroscience Laboratory, and CoRPS - Center of Research on Psychology in Somatic diseases - Tilburg University, Tilburg, The Netherlands.
2
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy; Division of Neuropsychology, Department of Cognitive Neurology, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany.
3
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy; Rehabilitation Unit, Zevio Hospital, Verona, Italy.
4
Department of Neuroradiology, Treviso Hospital, Treviso, Italy.
5
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy.
6
ASL 8 Asolo, Italy and University of Padua, Padua, Italy.
7
Brain Care and University of Turin, Italy.
8
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy.
9
Department of Neurological and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy. Electronic address: carloalberto.marzi@univr.it.

Abstract

Blindsight, i.e., unconscious visually guided behaviour triggered by stimuli presented to a cortically blind hemifield, has been typically found either by using direct (forced choice) or indirect (interhemispheric) methods. However, one would expect to find blindsight also in fast responses to suddenly appearing visual stimuli, a reminiscence of evolutionary ancient adaptive behaviour. In this study we provide preliminary evidence of this form of blindsight by using a conservative method for assessing blindsight based on a comparison between the cumulative probability functions (CPFs) of simple reaction times to blind and intact field stimuli. Furthermore, in two patients with blindsight we provided evidence that their above-chance unconscious responses were likely to be triggered by the intact hemisphere.

KEYWORDS:

Interhemispheric transfer; Perceptual awareness; Poffenberger paradigm; Reaction time

PMID:
25123328
PMCID:
PMC5053364
DOI:
10.1016/j.concog.2014.07.010
[Indexed for MEDLINE]
Free PMC Article

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