Multitasking — the ability to switch between doing two or more things at the same time — is something most people take for granted. Teens and young adults multitask as easily as second nature. They watch TV, update their Facebook page, answer a text from a friend, and have a book propped open to “study.”
However, as we age, it apparently becomes increasingly difficult to multitask well. So says a new study that has an explanation for the discrepancy.
Researchers have found that in order to multitask well, a person needs to be able to have good short-term memory — the memory we use to work with new information we take in right now. This working memory allows us to do those every day kinds of tasks we all do without thinking, such as writing down a note for a coworker or remembering a short list of groceries we need to pick up at the store.
The new research has discovered that the older we get, the harder it is for two parts of our brains to communicate with one another — the parts of the brain that deal with attention and memory.
“Our findings suggest that the negative impact of multitasking on working memory is not necessarily a memory problem, per se, but the result of an interaction between attention and memory,” said the senior author of the study, Adam Gazzaley, MD, PhD, an associate professor of neurology, physiology and psychiatry at the University of California – San Francisco.
The study shows that the brain’s capacity to ignore distractions, or irrelevant information, diminishes with age and that this, too, impacts working memory.
Researchers know that multitasking negatively impacts working memory in both young and older adults. However, previous research and anecdotal accounts of “senior moments” indicate that the impact is greater in older people.
In the current study, scientists compared the working memory of healthy young men and women (with an average age of 25) and older men and women (with an average age of 69) in a visual memory test involving multitasking.
Using functional magnetic resonance imaging (fMRI), the researchers tracked blood flow in the participants’ brains to identify the activity of neural circuits and networks.
Participants were asked to view a natural scene and maintain it in mind for 14.4 seconds. Then, in the middle of the maintenance period, an interruption occurred: an image of a face popped up and participants were asked to determine its sex and age. They were then asked to recall the original scene.
As expected, older people had more difficulty maintaining the memory of the original image.
When the young and older adults were interrupted, their brains disengaged from a memory maintenance network and reallocated neural resources toward processing the interruption.
However, the younger adults re-established connection with the memory maintenance network following the interruption and disengaged from the interrupting image. The older adults, on the other hand, failed both to disengage from the interruption and to reestablish the neural network associated with the disrupted memory.
“These results indicate that deficits in switching between functional brain networks underlie the impact of multitasking on working memory in older adults,” said lead author Wesley Clapp, PhD, a postdoctoral fellow in the Gazzaley lab.
The lab’s parallel research on the impact of distractions on working memory broadens the perspective of what happens in the aging brain.
The ability to ignore irrelevant information — such as most of the faces in a crowded room when looking for a long-lost friend — and to enhance pertinent information such as the face of a new acquaintance met during the search for the old friend — is key to memory formation.
“The impact of distractions and interruptions reveals the fragility of working memory,” said Gazzaley.
“This is an important fact to consider, given that we increasingly live in a more demanding environment, with a dramatic increase in the accessibility and variety of electronic media and the devices that deliver them, many of which are portable.”
The new research is reported in the online early edition of Proceedings of the National Academy of Sciences.
Source: University of California – San Francisco