Originally posted with title "Unconscious seeing".
A partial index of discussion notes is in
However the demonstration will not work for everyone: some people realise immediately what they have seen, and not everyone who fails to see it responds to the prompts when the original presentation is out of sight.
I have been using variants of this experiment in talks on vision for different sorts of audience since the mid 1980s. It usually works on a subset of the audience, e.g. between about 30% and 70% -- though I have not kept detailed records.
Alternative: view the demo on Youtube
There are two versions of the presentation: one uses this web site with a lot of textual material explaining what to do, but having to read the text may interfere with some of the processes.
To avoid that, a video version can be viewed here: http://youtu.be/qKPfy9IufG4
I would suggest trying that before looking at the non-video version presented below. But if you are unable to view a Youtube video you may find the version below of interest.
How it works
You should find a familiar announcement in the box.
Please examine it carefully, to make sure you see just a familiar sentence. If you see something wrong, and you are with somebody who sees nothing wrong, please do not say what you see. Just let the other person or persons continue with the experiment, without your saying anything.
After looking at the sentence in the box, please close the image because the rest of the experiment depends on your not having it in sight.
After looking at it, please come back here.
I think my earliest published reference to the experiment described here was in Sloman (1978), "What About Their Internal Languages?" Commentary on three articles
by Premack, D., Woodruff, G., by Griffin, D.R., and by Savage-Rumbaugh, E.S., Rumbaugh, D.R., Boysen, S. in Behavioral and Brain Sciences Journal 1978, 1 (4) pp. 515. http://www.cs.bham.ac.uk/research/projects/cogaff/62-80.html#1978-02
There is an extended discussion of the issues in:
All of this is a development of some of the ideas presented in my 1978 book The Computer Revolution in Philosophy: Philosophy Science and Models of Mind especially the points about the system and the environment containing each other, in chapter 6 and the ideas about relationships between consciousness and control architecture in chapter 10.
For more on the need to generalise Gibson's theory of affordances (and fix broken theories about the functions of vision in animals and future robots) see this presentation: What's vision for and how does it work?
"Blind Man Sees With Subconscious Eye" by Joe Palca NPR, 23 December, 2008
Blind Man Unknowingly Navigates Obstacle Course
Watch A Video Of The Experiment. (Joe Palca, Kathleen Masterson)
"TN has what is known as blind sight, according to de Gelder. Even though the primary part of his brain that processes visual information is destroyed, he still has more primitive parts of his brain intact, and these are capable of doing some visual processing. After all, one of the most basic functions of the visual system is to help an animal avoid obstacles or predators. TN still has some visual abilities - he's just not aware he has them."
Installed: 19 Oct 2009
Last updated: 12 Jun 2019;
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