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Sunday, April 05, 2009

Perception and Memory

Science Matters Program Explores the Accuracy of Eyewitness Testimony Presented by the California Science Center

Hey folks,

I would love to go here. For my friends in California, you should set some time aside and take the trip. Your kids will love it also, the California Science Center has a lot of fun stuff for them to do as well.

LOS ANGELES, April 3 /PRNewswire-USNewswire/ -- The California Science Center's Science Matters speakers program will investigate methods in our legal system with "Eyewitness Testimony: Perception and Memory on Trial" on Saturday, April 18, 2009, from 1:00 p.m. to 3:00 p.m. Eyewitness testimony is at the foundation of our judicial system, but its accuracy has recently been called into question by scientists and lawmakers alike. The discussion, which is free to the public, will question whether the practice of eyewitness testimony is scientifically sound or inherently flawed. Program panelists will explain the science of perception and memory that lies at the core of eyewitness testimony -- how we form memories, and how our perceptions influence how we remember. Science Matters will also discuss the consequences of the use of eyewitness testimony. Audience members are encouraged to visit the exhibits "Target America: Opening Eyes to the Damage Drugs Cause" and "CSI: The Experience" to get a look at the elements of forensic science.

Conan Nolan, NBC4 reporter, will serve as moderator for the panel discussion, in the Loker Conference room at the California Science Center.

Panelists include: Steven Clark, Ph.D. Professor of Psychology, University of California, Riverside; Jeff Sherman, Ph.D. Professor of Psychology, University of California, Davis; John Van de Kamp, Esq., Chair of the California Commission on the Fair Administration of Justice; and Julie L. Hamilton, Division Counsel, Drug Enforcement Administration, Los Angeles.

Program attendees will have a chance to hear the debates on this issue and to ask questions of the panelists at the end of the program. All those interested in attending may RSVP at 213-744-2420.

About the California Science Center

The California Science Center's mission is as follows: "We aspire to stimulate curiosity and inspire science learning in everyone by creating fun, memorable experiences, because we value science as an indispensable tool for understanding our world, accessibility and inclusiveness, and enriching people's lives."

OK. So I saw this, and thought, what about Perception and Memory? For those of you who might be new here, I LOVE Science. I always have. So things like this fascinates me. Kind of the whole point behind the Health and Science Segment.

I found this from Scientific America - Blurring the Boundary Between Perception and Memory, Dec 26, 2008

Can you trust your lying eyes—or any of your other senses and memory? Not really

Perception is mathematically impossible.

This might seem like a bold statement—after all, you are perceiving these letters right now—but it’s nonetheless true. Imagine a black-and-white line drawing of a cube on a sheet of paper. Although this drawing looks to us like a picture of a cube, there are actually an infinity of other three-dimensional figures that could have produced the same set of lines when collapsed on the page. But we don't notice any of these alternatives. Happily for all of us, our visual systems have more to go on than just bare perceptual input. They use heuristics and short cuts, based on the physics and statistics of the natural world, to make the “best guesses” about the nature of reality. Just as we interpret a two-dimensional drawing as representing a three-dimensional object, we interpret the two-dimensional visual input of a real scene as indicating a three-dimensional world. Our perceptual system makes this inference automatically, using educated guesses to fill in the gaps and make perception possible.

It turns out that our brains use the same intelligent guessing process to reconstruct the past, in addition to using it help perceive the world. Memory itself is not like a video-recording, with a moment-by-moment sensory image. In fact, it’s more like a puzzle: we piece together our memories, based on both what we actually remember and what seems most likely given our knowledge of the world. Just as we make educated guesses in perception, our minds’ best educated guesses help “fill in the gaps” of memory, reconstructing the most plausible picture of what happened in our past.

The most striking demonstration of the minds’ guessing game occurs when we find ways to fool the system into guessing wrong. When we trick the visual system, we see a “visual illusion”—a static image might appear as if it’s moving, or a concave surface will look convex. When we fool the memory system, we form a false memory—a phenomenon made famous by researcher Elizabeth Loftus, who showed that it is relatively easy to make people remember events that never occurred. As long as the falsely remembered event could plausibly have occurred, all it takes is a bit of suggestion or even exposure to a related idea to create a false memory
.

This is one of the reason I do not believe in Hypnotherapy. Way too many cases of people going to a Hypnotherapist and discovering that they were abused in their past. Some of these cases do not even make it to a trial because there is no real evidence that it has happened, yet some of the cases tear otherwise normal families apart and label innocent people abusers.

In the Blink of an Eye

In past literature, visual illusions and false memories have been studied separately. After all, they seem qualitatively different: visual illusions are immediate, whereas false memories seemed to develop over an extended period of time. A surprising new study blurs the line between these two phenomena, however. The study, conducted by Helene Intraub and Christopher A. Dickinson, both of the University of Delaware, reveals an example of false memory occurring within 42 milliseconds—about half the amount of time it takes to blink your eye.

Intraub and Dickinson’s study relied upon a phenomenon known as “boundary extension”, an example of false memory found when recalling pictures. When we see a picture of a location—say, a yard with a garbage can in front of a fence—we tend to remember the scene as though more of the fence were visible surrounding the garbage can. In other words, we extend the boundaries of the image, believing that we saw more fence than was actually present. This phenomenon is usually interpreted as a constructive memory error—our memory system extrapolates the view of the scene to a wider angle than was actually present.

The new study, published in the November issue of the journal Psychological Science, asked how quickly this boundary extension happens. The researchers showed subjects a picture, erased it for a very short period of time by overlaying a new image, and then showed a new picture that was either the same as the first image or a slightly zoomed-out view of the same place. They found that when people saw the exact same picture again, they thought the second picture was more zoomed-in than the first one they had seen. When they saw a slightly zoomed-out version of the picture they had seen before, however, they thought this picture matched the first one. This experience is the classic boundary extension effect. So what was the shocking part? The gap between the first and second picture was less than 1/20th of a second. In less than the blink of an eye, people remembered a systematically modified version of pictures they had seen. This modification is, by far, the fastest false memory ever found.

Although it is still possible that boundary extension is purely a result of our memory system, the incredible speed of this phenomenon suggests a more parsimonious explanation: that boundary extension may in part be caused by the guesses of our visual system itself. The new dataset thus blurs the boundaries between the initial representation of a picture (via the visual system) and the storage of that picture in memory.

So is boundary extension a visual illusion or a false memory? Perhaps these two phenomena are not as different as previously thought. False memories and visual illusions both occur quickly and easily, and both seem to rely on the same cognitive mechanism: the fundamental property of perception and memory to fill in gaps with educated guesses, information that seems most plausible given the context. The bottom line? The work of Intraub and colleagues adds to a growing movement that suggests that memory and perception may be simply two sides of the same coin.


So the next time that you seem to remember something in your past, think about this. Is it really your memory, or just a perception of what may or may not have happened. This is why I am big on letting the past stay the past, focusing on today. Like the old saying goes, "If you live in yesterday, dwell on tomorrow, all you will be is confused today." Or something like that.

Again, if you are in the Los Angeles area on April 18, it may be worth your while to check it out.
Peter

Sources:
Scientific America - Blurring the Boundary Between Perception and Memory Dec 26, 2008

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