A recent study from the University of California, Riverside has found that older adults are more likely to be distracted by irrelevant items when engaged in a physical task, such as driving a car or carrying groceries, than younger adults. The research wanted to examine the interaction between physical exertion and short-term memory performance when distractions were present or absent in both younger and older adults. Working memory, or short-term memory, is a core cognitive process that maintains information while engaging in ongoing mental activities, and inhibitory control is the ability to ignore distracting information that is not relevant to a task while focusing on relevant information.
Researchers recruited 19 older adults between the ages of 65 and 86 from local communities in Riverside, California, as well as 31 younger adults between the ages of 18 and 28 from psychology undergraduate courses at UC Riverside, who were given course credit. All participants were asked to grip a hand dynamometer, a device that measures grip force, at either 5% or 30% of their strength while they performed a short-term memory task. The participants’ grip was similar to that used when carrying a grocery bag, walking up a stairwell, or while driving. During the exercise with no distractions, they were shown three red bars momentarily and asked later to recall the bars’ orientation. With distractions, they were shown five blue bars as well and instructed to only remember the orientation of the red bars.
According to Lilian Azer, the first author of the research paper, older adults are less likely to ignore distractors in their surroundings when simultaneously engaging in a cognitive task and an effortful physical task in comparison to younger adults. “Ignoring task-irrelevant items declines with age, and this decline is greater when simultaneously performing a physical task – a frequent occurrence in daily life,” Azer said. The age-related differences may be amplified in situations where task demands are higher, such as having increased physical exertion or having more distractors.
Weiwei Zhang, who led the study and is an associate professor of psychology and a member of UCR’s Aging Initiative, stressed the importance of understanding age-related declines in physical and mental functions along with their interaction. He explained that as we grow older, we may experience a reduction in muscle mass and strength, and declines in key cognitive processes such as worse short-term memory, slower speed of processing information, and heightened distractibility as a function of normal cognitive aging. By 2030, older Americans will make up 21% of the population, up from 15% in 2018, and by 2060, nearly 25% of Americans will be 65 years and older.
Azer believes that effortful mental or physical activities are essential to our everyday functioning. For example, while driving, we tend to grip the steering wheel with about 30% of our maximum strength, and when we carry heavy shopping bags, we tend to use about 20% of our maximum physical strength. However, as we engage in these physical activities, we tend to have to simultaneously perform cognitive tasks where distractors may be present, such as a billboard or a car sales commercial on the radio. Inhibitory control may suffer during these concurrent tasks, making it more difficult, especially for older adults, to ignore the distractors and focus on task-relevant information.
The decline in our ability to ignore distractors as we get older is a result of normal cognitive aging, and the prefrontal cortex, a part of the cerebral cortex that has been implicated in remote memory consolidation, plays a role, and is typically involved in working memory and processes involving inhibitory control.
While the research has found that older adults may be more prone to distractors, the researchers are also interested in understanding the role of arousal induced by physical effort and how this arousal can impact response time and inhibitory control. The team plans to investigate the impact of effortful physical action on cognitive function further.
The study was supported by grants from the National Institute of Mental Health, National Institute on Aging, and National Institute of Neurological Disorders and Stroke.
In conclusion, while both mental and physical activities are essential for our everyday functioning, awareness of the impact of physical effort on cognitive function may help us minimize distractions and improve our ability to perform working memory tasks. This is especially important for older adults, who may face increased distraction and difficulty in ignoring irrelevant information that may affect their daily tasks.
