For a 2010 study, four doctors at the University of California, San Francisco divided adult subjects into two groups.
The individuals in one group were asked to examine a nature scene and, after a 15-second pause, answer a series of questions about it. These subjects had no trouble with the task.
The individuals in the second group were asked to perform the same task, but were interrupted. While answering the questions about the nature scene, they were shown a human face, and asked to identify the person’s gender and age. The doctors then resumed asking their questions about the nature scene.
The subjects in the second group who were under 60 had no trouble answering all the doctors' questions. But the subjects over 60 struggled to answer the questions posed after the interruption.
During the experiment, MRI scans of the subjects' brains revealed big differences in the brains of younger and older people, after the interruption.
Among the younger people, the brain-areas engaged when processing the picture of the human face shown switched off immediately after that interruption. But, among the people over 60, those brain-areas remained engaged after the interruption. The over-60 brains brains couldn't instantly switch back to the original task.
Besides concluding that multitasking erases the short-term memories of people over 60, the doctors also believe multitasking impairs the formation of long-term memories, because, to take shape at all, long-term memories require short-term ones.
Interruptions are inevitable. So how can people over 60 stay sharp, minimizing "senior moments" and maximizing long-term memories?
My prescription: Furnish your brain with care.
Leaf through any lifestyle magazine and you'll find an article that insists a serene mind requires a clutter-free bedroom (or living room, sitting room, den or home office).
Sir Arthur Conan Doyle thought a sharp mind did, too.
In A Study in Scarlet, Dr. Doyle's detective Sherlock Holmes tells his sidekick Watson the brain is like a "little empty attic."
The wise worker furnishes the attic with care.
"A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things," Holmes says.
"Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.”
Unless you're Watson—IBM's, not Doyle's Watson—letting trivia clutter the attic diminishes your ability to focus.
Literary man Dr. Samuel Johnson believed something similar.
"The true art of memory is the art of attention," Johnson said, referring to our ability to retain what we read.
"No man will read with much advantage, who is not able, at pleasure, to evacuate his mind, or who brings not to his author an intellect defecated and pure, neither turbid with care, nor agitated by pleasure. If the repositories of thought are already full, what can they receive? If the mind is employed on the past or future, the book will be held before the eyes in vain."