Key concepts

Have you ever tried to remember an entire list of groceries—without looking at the written list while you're shopping? Even a master of memory skills may fail to recall an item or two. But why does this happen? In this activity you will learn a little more about memory— how it works and what factors make some details more memorable than others. You will also re-create a psychology experiment that helped scientists identify two effects that can distinctly shape what we remember.

Can you recall all of the words in the paragraph above? No peeking! Some memories are stored for only short periods of time before they disappear. You need to remember the beginning of a sentence to understand the end, for example, but might not need to retain each sentence word-for-word to understand the whole paragraph. This briefly held form of recollection is called short-term memory. Other memories, however, last much longer. Scientists believe that a seahorse-shaped structure in the brain called the hippocampus helps us transform our memories from short- to long-term.

Another form of recollection is working memory. This is what helps you remember and juggle information that is involved in tasks in which you are engaged. This is the form of memory that lets you perform mental math, conjugate verbs or put together a list. Scientists have found that an area of your brain right behind your temples, called the prefrontal cortex, helps you carry out working memory tasks.

•    Pencils
•    Paper, preferably lined or graph paper
•    Watch or clock (optional)
•    Gather a group of friends and family to be your subjects—at least five people (but the bigger the group, the better your results)

•    Give each of your subjects a piece of paper and pencil.
•    Ask your subjects to listen carefully as you list 20 words. They will need to remember as many as they can but not write anything down until you tell them to.

•    In a steady, even pace—about one word every second if you are using a clock or watch—read the following list of words in order: home, dog, rock, hand, table, card, bag, monkey, phone, cookie, mouse, paper, nail, hat, pillow, water, juice, watch, circle and glass.
•    Why do you think your pacing matters? What do you think might happen if you repeated this activity and read more slowly? What if you read more quickly?
•    When you have finished reading the list, pause for one more second and then ask your subjects to write down as many words as they can remember.
•    Collect their lists and on a fresh piece of paper and prepare a line graph. The vertical y-axis of the graph will represent the number of subjects in your study. Starting at the bottom of this axis, write the number 1, then evenly space consecutive numbers until you have reached the total number of subjects in your experiment. If five friends participated, you will have the numbers 1 through 5 going up this axis.
•    The horizontal x-axis of your graph will include the words on your original list. Write these out, evenly spaced, in the same order that you read them. Your line graph will now allow you to pinpoint how many subjects remembered each of the words on the list.
•    Count up how many subjects correctly remembered each word. Above each word on your graph's x-axis, mark a dot that corresponds with the number of subjects along the y-axis. Are there certain words that everyone remembered? Are there words that all of your subjects forgot? Do some people have much sharper memories than others?
•    When you have placed a dot for each word, connect these points. Do you notice any patterns? Does your line graph have a smooth shape or is it spiky? Why do you think certain words were more memorable than others?
•    Extra: In the original list, all of the words are simple and concrete, making them easier to imagine and relate to. Repeat this experiment with a new list of short, common words but include some that are idea-based, or abstract. You could also read a list of real and made-up words. Are certain words harder to remember than others?
•    Extra: Distract your subjects by adding a working memory challenge at the end of the experiment. Repeat the above activity with a new list, but before your subjects write anything down, ask them to recite the last 10 letters of the alphabet backward. Then let your subjects write down as many from the original list as they can remember. Graph and compare your results. Does disrupting memory change the pattern of remembered words?
•    Extra: You can also try to enhance memory. First, strategize with your subjects on good memory techniques. For example, many people find that visualizing something makes it easier to remember. Try a few examples as a group, then repeat the experiment with a new set of words. Did your subjects remember more words with a little coaching?

Observations and Results
Did most people remember the first and last words on the list, but forget those in the middle?

Most people who try this experiment find their results create a U-shaped line graph. That means people do a good job remembering the beginning and end of the list, but struggle to recall words in the middle. Two different memory effects create this pattern. The primacy effect suggests that we are good at remembering the very first information we encounter. Scientists are still unsure exactly how this effect works, but one theory is that individuals trying to remember words will repeat the growing list each time a new term is added. As a result, they repeat the first few items more than any other and this repetition shifts information from the short-term to more secure long-term memory. The second effect is the recency effect. This suggests it's easier to remember what we learned last because it is still fresh in our minds. If these theories are correct, your working memory, which is trying to reassemble the list of words, struggles to recall terms in the middle because they haven't yet been stored in long-term memory and have been pushed out of short-term memory by more recent additions.

If you've ever written a book report, you may have encountered both of these effects—it's easy to remember how a book ends and you can probably recall how it began, but the middle gets muddled. Luckily, once you have recognized these effects you can also find ways to overcome them. In the case of that book report, taking extra notes is a simple solution that helps your memory keep details straight.

Recency and primacy are not the only effects that can influence your memory. You may have noticed that some words from the middle of the list were still very memorable. This could be because the words had special significance. For example, if a phone rang as you read "phone" or your subjects were very hungry when you said "cookie," these words could have gained added meaning.

More to explore
How does short-term memory work in relation to long-term memory? from Scientific American
Memory Experiments from Eric H. Chudler's Neuroscience for Kids
Memory and Learning from Bruno Dubuc, McGill University
Mapping Memory in 3-D from National Geographic
How Human Memory Works from
Working Memory from Thinker: A Cognitive Psychology Resource