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 HowStuffWorks.com
Working Memory from Thinker: A Cognitive Psychology Resource