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Author Topic: How do we recognize what we see ?  (Read 7057 times)

Offline neilep

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How do we recognize what we see ?
« on: 15/06/2004 21:33:12 »
Today I recognized all the things and people I know....how ?...I think this is an ability that we all take for granted but I assume it's a real complicated process.....

Your recognisable answers would be most appreciated:)...ta

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Offline valley

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Re: How do we recognize what we see ?
« Reply #1 on: 15/06/2004 23:04:38 »
I'm not sure anybody really understands it, but they have pinned it down to certain areas of the brain. I know there are cases of brain damage where people have lost the ability to recognise faces, which appears to be done separately from other types of recognition. I was at a lecture the other day where such a woman was mentioned - they had asked her how she recognised her husband and she said that she would look for the folds of fat on the back of his neck :)

Not so sure about objects, but it's interesting to know that there are neurons at the back of the eye, receiving inputs from the light receptors, that can individually recognise images such as lines, circles and squares (so if you prod one of these, you might see a red circle, or a blue line!).
 

Offline neilep

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Re: How do we recognize what we see ?
« Reply #2 on: 16/06/2004 01:40:33 »
Thanks valley.

Do you know if in the cases you've mentioned, that , is it only peoples faces that can not be recognized ?...is it so specific ?.......

I wonder if there are cases with the opposite symptoms i.e not being able to recognize objects.

Do you think memory plays an intricate part of recognition ?....I suppose it must really.

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« Last Edit: 16/06/2004 01:41:55 by neilep »
 

Offline chris

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Re: How do we recognize what we see ?
« Reply #3 on: 16/06/2004 01:44:21 »
New memories are encoded by a structure on both sides of the brain which is known as the Hippocampus due to its likeness to a seahorse. It also resembles a foot hence its alternative anatomical name, pes hippocampi.

These structures and the adjacent brain regions including the 'entorhinal cortex' are critical for new memory formation. This is illustrated by the famous example of HM a 27 year old man from Hartford, Connecticut who, in 1942 aged 16, developed severe epilepsy. His condition responded so poorly to the drugs available at the time that by 1953, at the age of 27, he was suffering ten or more fits per week.

The fits were originating from 'epileptiform foci' (hotspots of unstable brain activity that trigger epileptic seizures) in the temporal lobes on both sides of the brain. A neurosurgeon, William Scoville, reasoned that the epilepsy could be controlled by removing these abnormal bits of the brain. He was proved right after an apple-sized chunk of each temporal lobe (including the hippocampus) was removed from HM's brain - the seizures abruptly ceased. But so did HM's ability to form new memories.

He has excellent recall of his life prior to the procedure, and has 'short term' memory (he can remember things for up to 30 seconds at a time and can hold in memory number sequences of up to 8 digits) but he cannot form new long term memories. Every time the doctor looking after him came to see how he was he would have to re-introduce himself - HM hadn't a clue who he was. When asked to keep a diary of his days the entries repeatedly stated "I have just woken up" - because he assumed his lack of recall of what had happened 5 minutes previously must have been because he had been asleep. The news of his mother's death elicits the same grief reaction for a brief period on every occasion that he is told about it. He is also shocked by his own reflection every time he looks in a mirror.

HM is still alive (to my knowledge). He has a normal IQ but is locked into the 1950's and thinks his age is about 30. He cannot make new friends because he forgets people within minutes of meeting them, but he does enjoy doing crosswords.

The case of HM was the catalyst that provided vital clues about how memories are laid down. Clearly the hippocampus is not involved in short term memory, or long term memory, but probably provides the link that turns one into the other. Faces are indeed recognised in a specific part of the temporal lobe and damage to this region results in prosopagnosia, the inability to recognise faces. You've heard the joke that all foreigners look the same - but for people with damage to this part of their brain, you don't even need to be foreign for it to be a problem.

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx
« Last Edit: 16/06/2004 01:47:08 by chris »
 

Offline neilep

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Re: How do we recognize what we see ?
« Reply #4 on: 16/06/2004 02:53:00 »
That's facinating Chris, do you know if HM is, or ever was aware of his own condition ?

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Offline tweener

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Re: How do we recognize what we see ?
« Reply #5 on: 16/06/2004 02:53:48 »
An apple sized chunk????? That seems like quite an "abnormal bit" of brain tissue!

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Offline neilep

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Re: How do we recognize what we see ?
« Reply #6 on: 16/06/2004 02:55:38 »
Hey John, at least our brains are on the same wavelength seeing as we posted only 48 seconds apart....

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Offline chris

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Re: How do we recognize what we see ?
« Reply #7 on: 16/06/2004 08:17:25 »
Quote
Originally posted by tweener

An apple sized chunk????? That seems like quite an "abnormal bit" of brain tissue!

That's right, a significant piece of brain ! But it is often difficult to pin-point with precision the cells that are causing an epileptiform focus so to be sure to correct the problem (and avoid re-operation) a fairly radical approach was taken.

Chris

"I never forget a face, but in your case I'll make an exception"
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Offline chris

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Re: How do we recognize what we see ?
« Reply #8 on: 16/06/2004 08:19:11 »
Quote
Originally posted by neilep

That's facinating Chris, do you know if HM is, or ever was aware of his own condition ?

If you tell him what has happened to him he doesn't remember beyond the span of his short term memory. Intriguingly he likes watching detective stories on TV. I've no idea how he follows the plot. Unless he's watching Columbo of course, in which case there usually is no plot...

Chris


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Offline valley

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Re: How do we recognize what we see ?
« Reply #9 on: 16/06/2004 10:55:27 »
Yes faces are done separately from objects. The woman I mentioned drew a picture of how she sees her husband and the face was just mixed up / washed out colour. Very weird! However, I've heard of other people who can describe faces (fat, thin, yellow, big nose) but still just can't recognise them.

Faces are the thing our brains are usually best at interpreting, hence the fact that this -> [:0] is interpreted as being a face even though it's just an outlined circle with three black circles inside it. Also the reason why the Madonna's face appears on so many tortillas! In addition, have you ever wondered why A4/letter size paper is that size/shape? Hold it up to your head - it's like a squared off face. If you write a title on a blank piece of paper, you do it at the level where the eyes would be. We're designed to scan over human faces so find it easier to work with things that size/shape. There was a whole branch of Architecture which used such ratios for the same reason.

I was at a lecture the other day where they were talking about sheep recognising faces. Turns out they can remember 50 easily (sheep and human) and remember them for years. They seem to use the same methods as humans as we both have trouble if the eyes are blocked out or if the faces are upside down. Also, it seems that they prefer it if you smile at them (and it's just the smile, not the body language that does it)! Remember that next time you're walking across a field :)
« Last Edit: 16/06/2004 12:13:37 by valley »
 

Offline neilep

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Re: How do we recognize what we see ?
« Reply #10 on: 16/06/2004 12:04:42 »
I always smile when I'm eating my roast lamb :D............seriously though, I always thought A4 paper was that size because....well it's just one of many sizes but now that you mention it , it is the most popular size and you're right....I am at ease with all A4 sized documents :).....well....except bills etc

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Offline OldMan

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Re: How do we recognize what we see ?
« Reply #11 on: 17/06/2004 04:31:53 »
Babies up to somewhere around the 6 to 9 month age can recognise the face of a chimp just as well as a human face. If I recall correctly it was only after this age where they would only recognise human faces because of the higher level of exposure to humans.

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Offline qazibasit

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Re: How do we recognize what we see ?
« Reply #12 on: 26/06/2004 23:09:49 »
I will say a little about it and just take it in this way that our brain has a portion which saves the image of different objects and in case of any new object it wants us to give the brain more information about that thing and we use our 5 senses to do so and thus it is saved in the memory after that it is just the matching of the things with the previous one with all of its given data and hence we recognizes the things.
 

Offline neilep

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Re: How do we recognize what we see ?
« Reply #13 on: 27/06/2004 16:02:32 »
....so the brain must know that it is seeing something again to cause a reaction of familiarity....so...there must be a catalogue of everything seen and heard and smelled and experienced stored somewhere.....a ' brain template ' perhaps that is forever growing and being referred to then.

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Offline qazibasit

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Re: How do we recognize what we see ?
« Reply #14 on: 01/07/2004 00:43:42 »
ya there is a catlogue present in what the psychatrist called the subconcious which has all the data.
 

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Re: How do we recognize what we see ?
« Reply #14 on: 01/07/2004 00:43:42 »

 

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