Psychology in the News

October 7, 2008

Going beyond the magic number seven

Filed under: memory — Tags: , , — intro2psych @ 1:26 pm

by Allison Richmond

The Magic Numbers

The Magic Numbers

Is it possible to increase your short-term memory with practice? In one study, experimenters tested an undergraduate student with normal intelligence and memory abilities.  They read him strings of random digits in one-hour sessions over the course of 20 months.  At the beginning of the study, he could remember a string of 7 digits, and after over 230 hours of laboratory testing he could remember 79.  In addition to this feat, he could recall 80% of the digits he heard at each session as opposed to almost none at the beginning of the study.  The student accomplished this through the use of mnemonics, allowing him to use associations already stored in his long-term memory as opposed to using his short-term memory to remember all of the digits.

The student in this study used mainly running times as his mnemonic device, and when he was presented with digits that could not be organized in this way, his performance dropped drastically.  Many mnemonic strategies break down long strings of information into smaller, easier to remember chunks.  By transforming the information into running times, the student additionally increased his recall capacity because he was a runner, so the information was meaningful to him.  In addition to this mnemonic device, the student used a rehearsal procedure which broke the digits down into subgroups in a hierarchical structure.

Although it seemed as if the student’s short-term memory had increased, in fact his performance had improved through the use of mnemonics and hierarchical structures. Through these devices the student was able to recall long strings, without ever holding more than about seven distinct pieces in his short term, or working, memory  (Chase, Ericsson & Faloon., 1980)

The theory of the magic number 7 was developed by George Miller in 1956 (as described in  Meyers, 2007).  He proposed that the short-term memory could hold 7, plus or minus 2, bits of information at once that could be easily recalled.  We can remember random digits a little bit better than random letters, but in either case our short-term memory recall is limited, as is our ability to overcome the limit of the magic number 7, as shown in the study described above.

This study suggests that to improve our memory skills we should practice using mnemonic devices and learn to organize material hierarchically.  By making information meaningful and relating it to other information or to ourselves, we can encode it in our long-term memory, allowing us to store and retrieve the information readily.  This study is strong evidence that the best way to remember something is to relate it back to yourself or to old information.  So, next time you’re cramming for a test, try to make associations in addition to simply rehearsing the material.

References

Chase, W. G., Ericsson, A. K.  & Faloon, S.. (1980). Acquisition of a Memory Skill. Science, 208, 1181-1182.

Meyers, D. G. (2007). Psychology (8th ed.). Worth Publishers.

6 Comments »

  1. While the undergraduate student chose to associate number sets with running times already encoded in his long-term memory, another interesting memory technique is to associate random data with locations. This process is called the method of loci, a memory technique discovered by Ancient Greeks in which an idea is associated with a certain location (http://www.intropsych.com/ch06_memory/method_of_loci.html). This method can be used to recall a speech if certain locations in a room are associated with parts of the speech.

    Ben Pridmore, the current world memory champion, reports that he uses the loci method in order to recall a set of cards presented in a specific order. Pridmore says that he associates each card with an object or person placed at different locations in his grandmother’s house. When he wants to recall the set of cards, he takes a mental walk through the house, and as he comes across each person or object, the associated card is recalled (Watch Pridmore use the loci method at http://www.youtube.com/watch?v=Yp9qF-SjJZk). While the undergraduate student was lost when asked to recall digits that could not be organized into running times, Pridmore has been able to memorize the first 50,000 digits of Pi. The method of loci suggests that all one needs to do to recall random data is take a stroll through the mind.

    Comment by Katie Holdefehr — October 24, 2008 @ 6:58 pm

  2. In an article from Psychology Today, the writing staff from the magazine state that mnemonic devices might not be as reliable as previously thought. In a study by Alvin Wang, Ph.D., of the University of Central Florida, Wang and his team asked participants to learn list of words, one group using key-word mnemonics and the other rote memorization. While the participants who used key-word mnemonics had a better immediacy recall, after being asked the same words a week later, the rote memorization group recalled significantly more words. This study definitely adds a adverse spin on the “fool-proof” method of mnemonics devices.

    Psychology Today(1993). The Rain in Spain.Retrieved November 10, 2008, from http://www.psychologytoday.com/articles/pto-19930901-000021.html

    Comment by Robin Embick — November 10, 2008 @ 6:01 pm

  3. This was a very interesting post, but it is important to note that mnemonic devices do more than just break down “information into smaller, easier to remember chunks.” They also help the brain sort out which pieces of information are important. Our brains automatically are wired to disregard unimportant, trivial information. Giving subjects long lists of numbers to remember, with no connection to the real world at all, could easily be interpreted by the brain as pointless bits of knowledge, and would therefore purposefully not be remembered. If the brain thinks the information is trivial, the synapses will not proliferate and a strong link to our memories will not be achieved. On the other hand, by matching the data with a mnemonic device, the brain can recognize the information as something important and necessary, and the links in our memory will be stronger.

    “Why We Remember Important Things and Forget Trivia,” Science Daily (Retrieved December 13, 2008). http://www.sciencedaily.com/releases/2008/12/081202115201.htm

    Comment by Hannah Groch-Begley — December 13, 2008 @ 9:40 pm

  4. Although the use of mnemonic devices as a way to improve memory is a helpful tool, it really does not teach individuals to “go beyond the magic number 7″. By using mnemonic devices, people are able to remember more information by relating it to other significant numbers, however the magic number of 7 still applies. This technique merely allows people to store more information in these 7 things. Therefore, instead of only remembering 1 digit as one of these 7 things, they can remember 3 or 4 (or even more) numbers in the form of something else, like running times (such as 5:24) Then this running time, consisting of 3 digits, becomes 1 item out of the 7. Even though mnemonic devices do not allow us to break the rule of 7, it is still a very useful tool when it comes to memorizing information.

    Comment by Eadaoin Harney — May 4, 2009 @ 2:43 pm

  5. The author states that one way of encoding information into out long-term memory is by making the information meaningful by relating it to other information or to ourselves. This is often done unintentionally such as through songs. We associate certain information with songs, which are often thought as powerful memory cues. According to one study led by Richard Harris, professor of psychology at Kansas State University, one only need to think of the song, not hear it, in order to for a person to be reminded of such information. Harris says music can be a powerful memory cue because it’s multimodal, it combines words and instrumentation, for which we generally use different sides of our brains. Also, our brains may be primed to understand music in the the same way are primed to understand language. Thus, a useful way of enhancing memory could be through associating songs with specific information.

    Kansas State University (2009, January 23). Popular Songs Can Cue Specific Memories, Psychology Research Shows. ScienceDaily. Retrieved May 5, 2009, from http://www.sciencedaily.com­ /releases/2009/01/090121174126.htm

    Cady, E. T., Harris, R. J., & Knappenberger, J. B. (2008). Using music to cue autobiographical memories of different lifetime periods. Psychology of Music, 36(2), 157-177.

    Comment by Danielle Sloan — May 5, 2009 @ 7:30 pm

  6. One of the most critical use of chunking in our culture is of course the digit and letter sequences of telephone numbers, zip codes, PINs, and passwords. A study in the 1960s was done by Dr R Conrad, British Post, and Telecommunication Services studying the relative pros and cons of codes based on letters and numbers. One of the experiments was to visually present strings of letters. He noticed the most common errors were letters similar in sound. Even though the letters were presented visually the poor recall of acoustically similar letters shows that short-term memory store relies on an acoustic code too.

    Comment by Tarryn Sanchez — December 5, 2009 @ 12:19 pm


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