Description: After having two strokes a man has lost his sight. When you ask him what he can see, he says “Nothing”. Now, imagine that you ask him to walk down a corridor that contains a number of objects, pieces of furniture etc., without the use of his white cane. What will happen if you are able to convionce him to give it a try? Will you get yelled at for endangering a blind man? He will certainly bump into things, won’t he? But what if he doesn’t? If he navigates the corridor without bumping into anything would you decide he was lying to you about his lack of sight? What if he insists YOU were lying to HIM about there having been anything in the corridor he just walked along? What would be up with that? And how might that be explained in terms of the man’s brain-based visual processing system and his consciousness? Meet blindsight and read the linked article for a fascinating speculative ride!
Source: Blindsight: A strange Neurlogical Condition Could Explain Consciousness, Henry Taylor, The Conversation.
Date: July 1, 2020
So, what do you make of blindsight? One of the points I try to make when I speak about how sensations, perceptions, and internal controls are managed in the brain is that if you find yourself thinking of the brain as a large committee containing individuals with specific responsibilities; so with one entity driving and monitoring your mood state another monitoring and managing your hunger, another your thirst etc. then you have two possible explanatory challenges. One is that you do not have nearly enough “people” (or homunculi) in your brain functioning theory as it turns out that the functions of manipulating things like mood, hunger or thirst are distinct from the functions of monitoring such things (e.g., to mix theoretic metaphors, you need a furnace AND a thermostat to manage heat in a house). A second challenge is that you really need to stop thinking about little people in your head at all. Consciousness has been a huge part of our human life experience that Psychology continues to really struggle with. Blindsight is a fascinating opportunity to focus upon as the question of whether the blind man is or is NOT conscious of his ability to avoid bumping into things and, while it may seem simply confusing at first, it may provide an edge for Psychology to begin to worry away at the nature of human consciousness.
Questions for Discussion:
- What are the features of blindsight?
- What might it mean to ask if the blind man who can avoid bumping into things is conscious of their presence in from of him?
- How might blindsight get Psychology moving in its question to have something sensible to say about human consciousness?
References (Read Further):
De Gelder, B., Tamietto, M., Van Boxtel, G., Goebel, R., Sahraie, A., Van den Stock, J., … & Pegna, A. (2008). Intact navigation skills after bilateral loss of striate cortex. Current Biology, 18(24), R1128-R1129. Link
Jiang, Y., Costello, P., Fang, F., Huang, M., & He, S. (2006). A gender-and sexual orientation-dependent spatial attentional effect of invisible images. Proceedings of the National Academy of Sciences, 103(45), 17048-17052. Link
Norman, L. J., Akins, K., Heywood, C. A., & Kentridge, R. W. (2014). Color constancy for an unseen surface. Current Biology, 24(23), 2822-2826. Link
Phillips, I. (2020). Blindsight is qualitatively degraded conscious vision. Link
Irvine, E. (2019). Developing Dark Pessimism Towards the Justificatory Role of Introspective Reports. Erkenntnis, 1-26. Link
Stanbury, C., OJEDA, E. A. V., GOH, T. F., & NISBET, I. R. (2020). Do we have Unconscious Perception?. perception, 35, 47Z. or STANBURY, C. Do we have Unconscious Perception? (Doctoral dissertation, Monash University). Link
Ajina, S., & Bridge, H. (2017). Blindsight and unconscious vision: what they teach us about the human visual system. The Neuroscientist, 23(5), 529-541. Link
Mazzi, C., Bagattini, C., & Savazzi, S. (2016). Blind-sight vs. degraded-sight: different measures tell a different story. Frontiers in psychology, 7, 901. Link
Koenig, L., & Ro, T. (2019). Dissociations of conscious and unconscious perception in TMS-induced blindsight. Neuropsychologia, 128, 215-222. Link
Persuh, M., LaRock, E., & Berger, J. (2018). Working memory and consciousness: the current state of play. Frontiers in human neuroscience, 12, 78. Link