Now imagine your V1 is normal, but an evil genius removes your temporal lobes (the what pathway) under anesthesia. What would the world look like when you woke up? Without the what pathway, you wouldn’t be able to recognize, name or appreciate the meanings of things around you. Yet because the how pathway is intact, you would still “see” in the sense of being able to reach out for objects, to dodge missiles hurled at you or to avoid obstacles. It is hard to imagine this scenario, but it would be roughly equivalent to being transported to the Red Planet (without your knowledge) and waking up in a gallery of Martian abstract art. You could not recognize anything or understand it but could still find your way around, copy the shapes of things and step over fallen objects. Everything around you—chairs, tables, people, cars—would look like meaningless abstract art. You would have profound visual agnosia.
This kind of complete damage is rare, but even with partial damage a condition called Klüver-Bucy may develop. In this variant of agnosia the patient has some difficulty identifying common objects but more profound agnosia for food and appropriate “sex objects.” Patients cannot discriminate food from inedible objects, so they may put pebbles in their mouth. Such people may make sexual overtures to the patient in the adjacent bed, to the doctor or even to animals, though they are mentally normal in other respects.
Seeing without Naming
John’s predicament is somewhat similar. In some ways, it is more severe because he has great difficulty identifying any object. Yet he doesn’t take this to the absurd lengths of trying to eat inedible objects or engaging in indiscriminate sexual behavior. In Klüver-Bucy patients there is probably relatively greater damage to regions in the temporal lobes concerned with sex, food and other primal urges, whereas in John the damage mainly affects regions involved in recognizing more neutral and commonplace objects such as chairs, goats and carrots.
Recall, especially, that he could copy pictures accurately, although he was unable to identify or name them. This is because his how pathway is undamaged, and it can guide the hand around to draw a faithful rendering. Without the what (temporal lobe) pathway, he does not know what it is. Amazingly, he could even use shears to trim the hedge in his garden (which only requires how) but could not weed the garden because he had lost the ability to discriminate weeds from flowers. But his problems were not quite as extreme as seen in Klüver-Bucy; he could often recognize the general category that an object belonged to (“it’s an animal”) albeit not the specific exemplar (he might say “dog” instead of the correct “goat”). Or he would identify a carrot as a paintbrush (“because it’s long and has a tuft at its end”).
And thus we can begin to explain the unusual perceptions of GY and John, by examining their particular deficits in terms of our detailed knowledge of the visual areas and their connections and evolutionary origins. In doing so, we have not only explained these bizarre symptoms but also gained new insights into how normal vision works. Contrary to naive intuition, vision is not a single process. Instead it involves multiple specialized areas working in parallel. How the outputs of these areas are combined to create a seamless unity of conscious perception, however, is as yet an unsolved mystery.
Note: This story was originally published with the title, "I See, But I Don't Know".
See what we're tweeting about
7 Comments
Add CommentI wonder if it's possible that the "where" pathway developed separately from the "how" pathway in the visual cortex and that it functions on an unconscious level as an evolutionary adaptation. I could see the advantage in a threatening situation where having the brain begin to react to a potential threat by knowing where it's located and preparing a physiological response unconsciously would come in handy, rather than waiting for interpretation as to what the object is and how to interact with it. Perhaps the organization is useful in the way that the automatic withdrawal reaction is useful when touching a hot stove. You don't have to think about it, you just do it. Perhaps knowing where something is regardless of whether you know what it is proves useful for the same reason.
Reply | Report Abuse | Link to thisProof that all we sense is illusion can be seen in amputees, that have sensation in parts of missing limbs. How our brains can project an illusion of our surroundings OUTSIDE of us is a constant cause of fascination. When we turn our heads, our environment is detected as standing still. It will be a long time before we are able to program such sensing phenomena into robots!
Reply | Report Abuse | Link to thisi also have a blind sight disoderor visual blind sight disorder
Reply | Report Abuse | Link to thisi was watching discovery then i came to know that i have visual blind sight disorder in which a person is dong his functioning by watching the object if dont see the object i cannot do any thing.it is a risk factor for me in the scence of driving walking jams mostly tel me how can i prevent my self from blind sight dissorder this is mostly due to the defficiency of oxygen in the neurons or nerve cells nerve ceels are not active due to the defficency of oxygen. i m also a biologist.
I'd like to ask professor Ramachandran
Reply | Report Abuse | Link to thisa) if he thought consciousnee could be a spandrel of language (eg language mapping out the synthesis of long to short memories along such a route that they effectively produce a 'film' embedded within the none conscious operations of the body
b) do you think these conscious routes could be closely tracked by synesthetic connections so that particular memories associated with particular synesthetic 'landmarks' or neural connections stimulate or intensify the neural signals associated with 'multi-tasking' neural connectivity. So meaning is given to those neural events which tie together different sense perspectives of one activity.
Language being the locus of synesthetic connectivity between the senses. So a multiple of senses can find meaning in one symbol.
Or that correspondence between the neural locations(shared between sensory pathways) responsible for synesthetic correspondence i.e those neurons (in different sensory pathways) responsible for corepresenting the same object or action, collectively act as a 'switch' so to 'grab' an action or object and place it in either a conscious or sub or none conscious realm.
Reply | Report Abuse | Link to thisIn the conscious realm these signals resultant from the collective neuronal output are subsequently amplified and dissociated in such a way that a linguistic representaion is evoked. These pathways or associations being available for linguistic report.
Whilst the unconscious pathways are not so although synesthetic connectivity still allows control of the bady and its actions.
I argued that such human consciousness first arose with the use of portable mirrors or highly reflective surfaces whereby neuron systems were tuned accurrately so that these processes were first accurately coordinated through sensory feedback.
(Peter Reynolds - Didd Mirrors Cause Consciousness Tucson 2010).
Thinking on the hoof here - is it possible that deafness would have not been too big a disadvantage in the absence of language and might even have been an advantage in producing or enhancing a gesturally based language - so might have been tolerated earlier than blindness.
Reply | Report Abuse | Link to thisWould certain neural pathways have become unmasked in these individuals and when blindness came along as an 'allowable' disability, the interbreeding between the deaf and blind would cause synesthesia in the unmasked neurons associated with the enhance abilities seen in the deaf and blind.
Would this correspond to the 'new' or 'conscious' visual pathway described by Vilayanur Ramachandran and others or provide as specific type of feed into an older pathway so to distinguish it from what is now regarded as the older pathway.
These 'newer' neural pathways being associated with langauge in particular because it was the deaf in whom language was most clearly defined from a visual perspective.
Likewise this newer pathway would become more enhanced in offspring of the deaf and blind.
These pathways becoming unmasked in the general population according to the templates of cave art, whose narrative would instantiate and carve out routes that would lead to consciousness.
Being finally fully embedded with the use of mirrors and the constructive feedback from mirror use.
peter reynolds
reflectogenesis@hotmail.co.uk
Sorry the above was out of context.
Reply | Report Abuse | Link to thisI am postulating that consciousness came about from the interbreeding of the deaf and blind 50000 years ago which I am suggesting is the first time society had gained control of its evironment for the first time enough to support - firstly deaf (as this would not have been too great a disability given that language might not have existed) - and then the blind.
Bavalier et al suggesting that the remaining sense modalities in the deaf and blind are enhanced as compared to normally sensed humans)
Peter Reynolds
Reflectogenesis@hotmail.co.uk