reliability of eye-witness accounts

Ned,I have no data to back this up.Years and years ago, I read or heard that very early childhood memories were questionable. Since then from time to time I have asked people about their earliest memories or pay special attention when people recount these types of memories. Often when telling these tales other family members are very aware or these tales and often chime in and provide additional details.I suspect these are more often then not, stories that have been told to the people as they were growing up. Not only is memory tricky, but suggestion is also very powerful.

I'm fairly sure my 'earliest memory' is factitious. For one thing it occurred when I was still in my cot and for another I always recall it in a 3rd person view. I also don't remember remembering it, if that makes sense, before my mother 'reminded' me of it when I was 8 or 9.TTFN,WK

Funny, just today I came across this while looking up something totally unrelated to memories.Sucuri WebSite Firewall - Access DeniedRandi, as in ‘The Amazing Randi’ talks about memory in an article about eye-witness reports of abductees. Interesting that we’re so quick to dismiss their sworn testimony and so quick to accept other types.

Well thats true, but extraordinary claims and all.I think the important part in Randi's article was the observation that we "see" about 170 degrees of angle but only about 1 degree in focus. That limit to our physical mechanism of perception can produce all sorts of illusions, including those relating to UFO's as fast moving lights, as I recently mentioned. Another excellent example was a BBC prog a couple of years ago that perfoermed this experiment: they had two basketball teams and asked the audience to count how many times the ball was passed. Then a man walked on in a gorilla suite, waved at the audience, and left - and nobody saw it, becuase they were all tracking the ball.When a gorilla can walk in front of you, wave, and leave without you noticiing, I think you have to concede that eyewitness testimony can be very unreliable indeed.Also, this is a big change in understanding from the old idea that the last image seen by the dead would be captured on their retinae.

I agree. I don't *know* that it is 1% or focus means the rest is out of focus. It does seem clear that we 'focus', as in actively take in a lesser part of the area we see.I like Randi and find myself often in agreement with him, but he often tosses out comments like that without providing sources.

Two factors here.1. Our cones (sensitive to bright light only; 3 types transmitting differential information based on color and brightness, and PACKED) are focused in the fovea, a very focused region in the center of the retinal.The rest of our retina has more sparsely dispersed rods (sensitive to lower levels of light, do not transmit any color information) and a "few cones here and there" (or maybe no cones at all. I can't remember).The region of space that the fovea region receives light from is small; on the order of 1 degree. So I guess that's what's being talked about here.2. ATTENTION. It's been shown (I don't have a reference handy) that people's attention can become "focused." For example there was a study of eyewitness testimony where eyewitness memory accuracy (and confidence) was tested in two scenarios. In the first, somebody demanded their money. In the second, somebody pointed a gun at them and demanded their money. The confidence of recall of the identity of the thief was the same in both conditions, but the accuracy significantly decreased in the second (with gun) condition. The reason? The participants focused their attention on the gun, not the attacker.I think this 'attentional' point is important, as well as schraf's earlier point about our memory systems. Clearly studies have shown that, due to the structure of our memory systems and the way we store things, memories are highly, highly reconstructive. It's almost pointless to call them reconstructive--there's just no available concept in there of "recorded" information. There is no such thing as "unprocessed" information. And especially for any information that was processed consciously. That's so far downstream... anyhoo.Ben

Well, the 1% that Randi cites seems quite close to the rule of thumb I was taught: you only focus on an area about the size of a 5p coin held at arms length. Thats probably a bit less than centimeter or so in diameter. This fact is heavily used by stage magicians: the hand is not quicker than the eye; the eye is in the wrong place. (and, often, was put in the wrong place by misdirection).There are lots of optical tricks like this: for example, the SADF used a rule that when scanning terrain, you should always do so from right-to-left, because scanning left-to-right triggers an interpolative hop like that used when reading text.Its also echoed by work done by Desmond Morris, IIRC, in which they tracked eye movements when people looked at a picture of a person, and the focal zone moved around a lot - mostly from eye to eye, but also down to the mouth and across the brow. Thats fits exactly with a focal zone that is actually very small.The subjective image we have of the world around us is an illusion, a virtual reality comprised of an interpolation of the bits the focal zone has actually examined. The effect occurs, as I understand it, because the quantity of colour-detecting cone elements in the retina is quite small, and in effect the focal zone is whatever image is being directed right on to the cones. Most of the retina is comprised of rod elements, which detect only light intensity (thus, black and white) and movement. Thats why your "peripheral vision" can warn you of a fast moving object even outside the focal zone.Again, this matches the experience of fighter pilots - it is literally the case that you have to actually look at every degree in the sky to see an aircraft in the distance - otherwise you will only detect it via movement being detected when it is very close.I've not been able to find an actual discussion but this extract of jargon might help:Focal VisionIngle, Schneider, Tevarthen, Held 67-68)The role of vision involved in the examination and identification of objects associated with the fovea and exploratory eye movements. (As opposed to Ambient Vision)
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FoveaThe area of the retina associated with the highest concentration of cones and therefore the highest acuity. Humans move their eyes so that images of interest are projected onto their foveas.
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Ambient VisionIngle, Schneider, Tevarthen, Held 67-68)The role of vision involved in orienting an animal in space and guiding its larger movements. Sensitive to motion and dependent on peripheral vision. (As opposed to Focal Vision).

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In the first, somebody demanded their money. In the second, somebody pointed a gun at them and demanded their money. The confidence of recall of the identity of the thief was the same in both conditions, but the accuracy significantly decreased in the second (with gun) condition. The reason? The participants focused their attention on the gun, not the attacker.

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As I recall there is a similar vignette in an episode of Hunter:"What did he look like?"
"About 6 inches long, and sharp"

I agree that humans seem to have a great capacity for tuning out input. I suppose if one considers vertical space then 1% seems reasonable.I would have preferred he had used ‘in focus’ or ‘focal-area’ rather than simply ‘focus’, especially when dealing with a human’s ability to take in information. It just seems to me that he’s using focal-area to argue that humans receive nothing useful outside that area. While I can’t read outside that area, I can often make out shapes and color.

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While I can’t read outside that area, I can often make out shapes and color.

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As I undrestand it, that is mostly an illusion.Have you ever head a driver exclaim "he came out of nowhere"? That person could well have been in the full field of vision, but if they had never fallen under the focal zone, they would never be represented. They would then appear to "pop" up out of nothing when you finally looked in that direction.I've had this happen to me in FPS games.

Not disagreeing with you, but I think we’re talking about two different aspects. Consider this:Look at the text on this message board. Now when I place both my focus and my focal-point on a single word, and I don’t’ move my eyes, I find my ability to read the surrounding words limited to an area much smaller than the whole. On average this is just a few words, if even that much, on each side of the word I am currently focused on.Now, I have a baseball cap resting next to my monitor, and even while I can’t make out the logo on the cap, I can tell it is golden and a baseball cap. My point is that I can take in more information of some types than the 1 degree or so on the focal-point.So I’m not disagreeing that a person might fail to note items outside of the focal-point, but obviously at least some of the time items outside of the focal-point are considered. The best examples of this I can think of are changes to lighting at the periphery and moving objects entering one’s field of vision.

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Now, I have a baseball cap resting next to my monitor, and even while I can’t make out the logo on the cap, I can tell it is golden and a baseball cap. My point is that I can take in more information of some types than the 1 degree or so on the focal-point.

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OK, I follow. But, remember the man in the gorilla suit?This is what is happening: 1 minute ago, you looked at the cap. That cap has been "drawn" inside your head as being over there. You are NOT actually looking at the cap right now - you are looking at an old image of a cap that WAS there a minute ago. It might still be there - but it might not. You won't find that out till your focal zone checks that point and updates your internal representation.Its the reverse of "he came out of nowhere"; in that scenario, I the driver have an internal representation of "an empty road" when in fact the road is not empty any more. I jst don't look in that direction till the last minute - and then suddenly the person is drawn into my representational space and *poof* "he came out of nowhere".I actually had another thought about this overnight as well. Soemtimes if you are really tense and enagegd in action you can get tunnel vision. I would suspect this is the brain deciding not to bother with the illusionary representation of anything other than what is in the focal zone right now. So you experience the sensation of your vision "contracting" into a tunnel.

To add to contra's comments-Much of false memory doesn't simply involve "missing" details, it involves the brain interpolating information that isn't really there. In the baseball cap scenario, imagine you look away for a moment or leave the room briefly, and someone quickly and secretly changes your baseball cap with something generally similar in shape and color - say an upside down yellow cereal bowl. You may return your focus to your monitor and not notice the exchange for some time, until you actually choose to focus on the object - throughout that time your awareness will be that the hat is still there, because that is how your brain will fill in those details based on previous experience.Your brain interpreting/interpolating the baseball cap for the cereal bowl is a similar phenomenon to failing to notice the addition or substraction of a word in a sentence - one often reads the sentence with their brain adjusting for the error based on the expected pattern. (This is one reason it is always good to have someone else review your writing, since you may miss errors since your brain reads past mistakes based on your intended form of the sentence).Unfortunately similar interpolation can occur in eye-witness accounts of crimes as well, where the brain of someone who witnesses a crime committed in someone in a golden baseball cap "fills in" the face of an innocent person they passed on the street the day before that was also wearing a golden baseball cap.Compensation for such exchanges has been demonstrated in quite drastic scenarios, including the exchange of an entire person. Research has shown that you can actually exchange people during a conversation and not have the subject notice the change. You can see video of these experiments at the University of Illinois Visual Cognition Lab, as well as other experiments that are relevant.This message has been edited by pink sasquatch, 03-16-2005 01:32 PM

I am not currently talking about memory, that memory is an imperfect process is a given for me.All I have been saying is that I believe that there is useful visual information gathered from outside the fully-focused area. I believe some color and farther out light and movement.Edited to clearify.This message has been edited by Trae, 03-21-2005 12:14 AM

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This is what is happening: 1 minute ago, you looked at the cap. That cap has been "drawn" inside your head as being over there. You are NOT actually looking at the cap right now - you are looking at an old image of a cap that WAS there a minute ago. It might still be there - but it might not. You won't find that out till your focal zone checks that point and updates your internal representation.

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If this were always true, how would I be able to process new, previously unknown, objects? I am not saying that objects are always processed outside of the focal zone. I am not even saying that people normally process items outside the focal zone. I am saying that is possible to have some input from objects outside of the focal zone. Isn’t that in part demonstrated by visual periphery tests?