Lexington, Virginia • August 13, 2009
We know that as people age their responses and decision-making processes slow down. What we don't know exactly is why this happens.
Wythe Whiting, associate professor of psychology at Washington and Lee University, hypothesizes this may be due to a breakdown of the brain's neural circuitry, resulting in what he calls "neural noise." "This means we lose neural connections and we process information at a slower rate," he said.
Whiting and two W&L students have been testing his theory this summer in W&L's Cognitive Lab, with interesting results.
They compared the responses of a group of young adults 18 to 29 years old with a group of adults 60 years and older. There were 32 individuals in each group.
The test subjects were asked to look at a computer monitor and pick out target lines that were different from other lines. For example, they needed to find the green line among the orange lines or the line that tilts left instead of right. Noise was added in the form of visual static on the computer screen.
"If older adults already have, as I've hypothesized, more neural noise, and you exacerbate it by adding more noise, then the older adults should be much slower in identifying the target lines than the younger adults," Whiting explained. "Basically, the faster they identify the lines, the healthier their nervous system is."
The research team found that the older adults were disproportionately more susceptible to the static noise than the younger adults.
In a previous experiment, Whiting had found that older and younger adults were affected similarly by the external noise. But that was because the subjects knew what they were looking for. "They might get a whole series of trials where the target was always green among orange distracters," he said. "That familiarity meant they could ignore the noise fairly easily."
This summer that experiment was altered. "We made the experiment so that subjects didn't know what the target feature was going to be," explained Whiting. "When they didn't really know what to look for, when they simply had to find the odd item, then they were much more susceptible to the noise.
"In the first experiment they had used their experience and knowledge to filter out the noise. When they didn't have that to rely on, the older adults had more difficulty coping than the younger adults."
Whiting used driving an automobile as an example.
"You may know how to drive a car, but the problem is when you have some distracting feature such as the noise of heavy rain. If you're driving in the rain with degrading visual signals, as long as you're traveling along your usual route you're going to do fine. But when you have to travel to a new location in the rain and you're looking for a street sign that you've never seen before, then it's going to be more difficult" he said.
Camille Sample, a rising junior with a neuroscience major, said that she was surprised at how distracting the static noise was to the older adults. "I wasn't really expecting that," she said.
For both Sample and Katie Blackburn, a rising junior and psychology major, this was their first research project. "The entire process has been really interesting," said Blackburn." I had no idea of all the steps that are involved, from designing the tests and conducting them to analyzing the data. I've learned a lot."
"I think it's interesting that the students get to learn all the nitty-gritty details of what research and the scientific process is all about," said Whiting. "It's very precise and controlled and you can't have a single small error. It has to be just right."
Whiting has been working on aging and cognition research since 1993, and said he has tested close to one thousand adults. He has published articles about his research in the journal Psychology and Aging. The last article was the first that resulted from his research while at W&L, and a student who assisted in the research was named as a co-author.
Both Sample and Blackburn are R. E. Lee Research Scholars. Sample's support was funded through the Levy Neuroscience Endowment for student summer research.
R.E. Lee Research Scholars are part of the University's undergraduate research program which is in its fifth decade of operation. It was founded in 1960 by an 1899 graduate. Students must be nominated by their professors to be R.E. Lee Research Scholars. It involves either assisting a professor in research or carrying out a student-planned project under the supervision of a professor.