Residual Visual Function after Brain Wounds involving the Central Visual Pathways in Man

Pöppel, Ernst; Held, Richard; Frost, Douglas O.

doi:10.1038/243295a0

Cited by 731 publications

(300 citation statements)

References 13 publications

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“…If we use it, then, together with T p , there are a variety of experimental results that indicate the existence--indeed, prevalence (in certain unusual cases)--of unconscious or implicit perception. Today, perhaps the best-known of these is blindsight (Pöppel, Held, and Frost 1973;Weiskrantz 1997), a condition in which patients with a partial "blindness" due to lesions in the visual cortex report seeing nothing in their blind field (thus, according to s T a , lacking awareness of the objects that are there) while obtaining information about them (as revealed by forced choice). Such accurate performance …”

Section: Conscious Awarenessmentioning

confidence: 99%

Perception without Awareness

Dretske¹

2006

Perceptual Experience

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We appear to be on the horns of a dilemma with respect to the criteria for consciousness. Phenomenological criteria are valid by definition but do not appear to be scientific by the usual yardsticks. Behavioral criteria are scientific by definition but are not necessarily valid.--Stephen Palmer in Vision Science: Photons to Phenomenology (p. 629) Unknown to Sarah, her neighbor, a person she sees every day, is a spy. When she sees him, therefore, she sees him without awareness of either the fact that he is a spy or the fact that she sees a spy. Why, then, isn't the existence of perception without awareness (or, as some call it, implicit or subliminal perception) a familiar piece of commonsense rather than a contentious issue in psychology? 1 It isn't only spies. We see armadillos, galvanometers, cancerous growths, divorcees, and poison ivy without realizing we are seeing any such thing. Most (all?) things can be, and often are (when seen at a distance or bad light), seen without awareness of what is being seen and, therefore, without awareness that one is seeing something of that sort. Why, then, is there disagreement about unconscious perception? Isn't perception without awareness the rule rather than a disputed exception to the rule?I deliberately misrepresent what perception without awareness is supposed to be in order to emphasize an important preliminary point--the difference between awareness of a stimulus (an object of some sort) and awareness of facts about it-including the fact that one is aware of it.When in the course of ordinary affairs S sees a spy without realizing he is a spy, S, though not

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Section: Conscious Awarenessmentioning

confidence: 99%

Perception without Awareness

Dretske¹

2006

Perceptual Experience

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“…Weiskrantz, 2002;de Gelder, Tamietto, Pegna, & Van den Stock, 2014;de Gelder, Vroomen, Pourtois, & Weiskrantz, 1999;Hamm et al, 2003;Heywood & Kentridge, 2000;Morris, DeGelder, Weiskrantz, & Dolan, 2001;Pegna, Khateb, Lazeyras, & Seghier, 2005;Rossion, de Gelder, Pourtois, Guerit, & Weiskrantz, 2000;Tamietto & de Gelder, 2008;Tamietto, Pullens, de Gelder, Weiskrantz, & Goebel, 2012;Tamietto et al, 2009;Van den Stock et al, 2011). As is the case for the original phenomenon of ''blindsight'' (Pöppel, Held, & Frost, 1973;Weiskrantz, Warrington, Sanders, & Marshall, 1974), the ''blind'' component in affective blindsight refers to the patients' statement of not seeing or consciously perceiving the emotional stimuli, while the ''sight'' component reflects their residual ability to respond, discriminate or display spontaneous expressive and physiological responses that are appropriate to the specific emotional content of the visual signals they are presented with.…”

Section: Introductionmentioning

confidence: 99%

From affective blindsight to emotional consciousness

Celeghin

Gelder

Tamietto

2015

Consciousness and Cognition

113

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a b s t r a c tFollowing destruction or denervation of the primary visual cortex (V1) cortical blindness ensues. Affective blindsight refers to the uncanny ability of such patients to respond correctly, or above chance level, to visual emotional expressions presented to their blind fields. Fifteen years after its original discovery, affective blindsight still fascinates neuroscientists and philosophers alike, as it offers a unique window on the vestigial properties of our visual system that, though present in the intact brain, tend to be unnoticed or even actively inhibited by conscious processes. Here we review available studies on affective blindsight with the intent to clarify its functional properties, neural bases and theoretical implications. Evidence converges on the role of subcortical structures of old evolutionary origin such as the superior colliculus, the pulvinar and the amygdala in mediating affective blindsight and nonconscious perception of emotions. We conclude that approaching consciousness, and its absence, from the vantage point of emotion processing may uncover important relations between the two phenomena, as consciousness may have evolved as an evolutionary specialization to interact with others and become aware of their social and emotional expressions.

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“…Although this does not necessarily prove that conscious visual percepts are created thereafter all, we are blind if the eyes are destroyed, but no one suggests that visual consciousness is created there-it does indicate the importance of V1 to visual awareness, especially as destruction of no other visual area produces phenomenal blindness. Despite this blindness, some patients possess blindsight, which is the ability to respond in a highly successful manner and by forced choice guessing to visual stimuli they deny seeing (Pö ppel et al 1973;Weiskrantz et al 1974). For example, they can detect, localize and even discriminate between a large range of visual stimuli, initially to their surprise because they are at a loss to explain how they do so.…”

Section: (D) the Perception Of Visual Motionmentioning

confidence: 99%

The Ferrier Lecture 2004 What can transcranial magnetic stimulation tell us about how the brain works?

Cowey

2005

Phil. Trans. R. Soc. B

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Transcranial magnetic stimulation (TMS) is a technique whereby parts of the cerebral cortex and underlying white matter can be excited by a brief electrical current induced by a similarly brief, rapidly fluctuating magnetic field which is itself produced by rapidly discharging a current through an insulated coil held against the scalp. When combined with magnetic resonance structural and functional images of the subject's brain, the stimulation can be directed at specific cortical areas. Over a period of only 15 years, TMS has revealed hitherto unsuspected aspects of brain function, such as the role of distant parts of the brain in recovery from stroke, and has helped to resolve several previously intractable disputes, such as the neuronal basis of conscious awareness. This article describes and discusses the origins and nature of TMS, its applications and limitations, and its especial usefulness in conjunction with other techniques of evaluating or imaging brain activity.

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Residual Visual Function after Brain Wounds involving the Central Visual Pathways in Man

Cited by 731 publications

References 13 publications

Perception without Awareness

Perception without Awareness

From affective blindsight to emotional consciousness

The Ferrier Lecture 2004 What can transcranial magnetic stimulation tell us about how the brain works?

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