Of mulitple bananas

12 07 2009

I was briefly thinking about the visual invariance problem, which is the question of how does the brain objects even when the same single object (a banana) looks very different from differing angles of view e.g. end on Vs side on.

My thought is somewhat separate which is how does the brain recognize 2D images? for example, you can if shown a picture of a banana (never having seen on before) and be told what it is, then go on to recognize a real one easily enough, but on pure based on visual data a 2D image has very different information than a 3D image yet the brain copes why? This matters too to those of us who run physiological experiment by showing 2D images if these are being processed differently for real 3D images then were not quite asking the question we though we were :).

My suspicion is that what the brain is doing is when ever it is sees a 2D image is that it is constructing a 3D image from it, so when you see the image of  banana you make a 3D model of one which is (somehow) stored appropriately in memory and can then have the usual recognition methods applied to it to deal with problems such as visual invariance. This would after all make an evolutionary sort of sense as the brain evolved not to deal with pictures (which only existed incredibly recently) but to deal with real 3D objects.




Edit: went away and had a cup of tea… sorted it out now. It occurred to me that in reality the brain never ever actually sees a 3D world, the eyes report data in a 2D form as that is all they can do by pure observation of the world. The brain then constructs a 3D world view from that 2D scene by the use of a large number of processes and mechanisms (e.g. shadow depth), and then uses that 3D model internally. So what is really happening in the brain when you see a 2D object is that it automatically deploys this same series of mechanisms to turn things into a 3D object. So i believe that for the brain (post visual processing) that this IS no such thing as a 2D object everything is processed into 3D automatically, thus solving the problem.

Edit 2: post another cup of tea (never under estimate the powers of tea), this ought to be experimentally testable, you should for example be able to fool the recognition system, by presenting an image of a novel object (say a banana) but with false perspective ques, which would make it say fatter than expected and the compare people perceptions of the different between their expectations and the real object.

Of course a problem to still to deal with here is that we can also recognise an object from someone giving as a verbal description and then us presumably constructing a 3D model from that, quite how a brain that has only faced this problem in the last 100,000 years or so (tiny in evolutionary terms) is able to cope with this is unknown. But is defiantly one of the reasons I remain fascinated with it!

Hello world!

15 01 2009

Hello World indeed, that as a matter of curiosity always used to be the first thing to learn how to do when learning a new computer language so I think it will be appropriate to keep.

This until such time as a better idea occurs to me will be a place to keep random thoughts about neuroscience, consciousness, ai, psychology and various other things as they occur to me.

So a starting thought?

Well some time ago I attended a talk on a project called heart robot (http://www.heartrobot.org.uk/) – short versions its a robot designed to make you like it – its a simple response machine with no real brain as such.

The things that intrigued me was that when this robots was shown to normal people, they like you would to a baby and started to assign in motives e.g. its angry or sad. So began to treat it as if it was a animal with a mind of its own, in theory of mind terms they assigned it one. – a theory of mind is a generic name for your ability to assign motives and intentions emotions etc to humans that are not you, for example when you see someone in a supermarket you predict where they will go be analysing their motives etc as opposed to treating them as reaction machines e.g. they have beans, beans = move left.

What I was curious to wonder was what happens if you present this robot to highly autistic/aspergers children. One of the symptoms of those conditions is finding it very hard to work out the internal motives of  other beings or items. Theirs are two possible outcomes both interesting

1) Would you find that they treat it as an automation (which is all it really is) and to imagine it as another human type being – so no dolls tea parties for example – this would then suggest that what the autistic children lack is a theory of mind

2) they react as most other people do and treat it as a human type being – which suggest either that no theory of mind is involved or that they do have one. A subset of this is would they find the robot easier to cope with? after all its number of reactions are considerably reduced compared to even a footballer! – in which case they do have a mind theory but a reduced capacity version.

Either way i think it would be an interesting experiment to try….

stay tuned for more randomised thoughts….