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Are memory loss and cognitive decline inevitable parts of the aging process? Many new studies suggest otherwise. Scientists are searching for ways to keep people mentally fit throughout their increasingly long life spans. Meet William Greenough, one scientist who believes that keeping the brain active requires both physical and mental workouts throughout life.

Curriculum Links
National Science Education Standards
Discussion: Memory and Aging
Activity: Test Your Memory



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It had long been assumed that as people grew older, they lost neurons (brain cells) and thus experienced a decline in mental and cognitive abilities. Recent studies challenge this assumption. Evidence from recent brain research suggests that mental decline in older people is not inevitable. One study recently concluded that people with higher levels of education -- or rich, active lives -- may be less susceptible to developing Alzheimer's disease later in life. In a stunning study, Princeton University researchers reported new evidence in 1999 that neurons may actually regenerate -- contrary to beliefs held for the last 100 years.

As we see on Frontiers, enrichment and activity is just as essential to mental functioning as it is to physical functioning. Connections between brain cells (synapses) help people remember thoughts, skills, experience and knowledge. By keeping these connections in shape, brains of all ages can stay mentally fit.


We use different memory systems every day. One kind of short-term memory is called working memory. It operates for a few seconds -- long enough to remember a phone number as you dial it. Several studies have suggested that the maximum number of items the human brain can successfully recall in working memory is seven. How might you test this theory?

Test your short-term memory with these activities. Work in pairs or small groups to conduct these experiments.

One person on the team should devise a string of seven random numbers and/or letters, such as 9748320 or JWQYTLO. Speak the numbers or letters aloud to your partner. See if your partner can repeat the series back to you immediately after hearing the information. Try it again one minute later, five minutes later and 30 minutes later. Chart the results. What happens when the string of items is extended to more than seven? Try the same experiment with ten or more numbers or letters, or try a similar experiment with grocery items. Graph and compare results.

Each person on the team should draw or cut out ten or 12 pictures of common objects and arrange them on a large piece of paper or cardboard. Cover the paper until you're ready to begin. Show your partner the pictures for 30 seconds, then cover the board. How many of the pictures can your partner recall?

Try a variation of this experiment using real objects placed on a cafeteria tray. Cover the objects until you're ready to show them to your partner. Change the experiments by varying the number of objects and the time of exposure. Chart or graph results. Does the number of items or the time of exposure make a difference in recalling them?

Witnesses to a crime can be extraordinarily unreliable in their recall of events. To test the eyewitness abilities of students, have a small group of students create a disruption during class -- come into the room wearing disguises, open and close the blinds, drop things on the floor, and so on. After they leave, announce to the rest of the students that this is a test. Have them write down exactly what they observed. How accurate is their recall? You might also work with another teacher to set up a similar experiment with an unknowing class.


  1. If possible, try some of these memory experiments with people of different ages. Anecdotally, it's been said that older people seem to forget what they just heard. Do experiments support this assumption?

  2. Memory is a complex phenomenon that involves many parts of the brain. Research more about brain anatomy and present illustrations showing the different regions of the brain and their functions, as known.

  3. Design experiments to test the memory skills of various pets.

  4. Apply Bill Greenough's research to elderly people living in a retirement home. How would you structure their activities to stimulate and invigorate the brain?

  5. Researchers are racing to find cures for Alzheimer's and other diseases, because as the world's population ages, many more people will need treatment. It's estimated that 1 in 5 people over age 85 will develop Alzheimer's. Bring in news clippings about research into new treatments and discoveries about memory. Discuss the findings.

  6. For more interactive memory games and experiments, visit NASA's Cognition Lab at Another website for interactive memory games and for learning more about the brain and current research in neuroscience is


Scientific American Frontiers
Fall 1990 to Spring 2000
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