Danah Henriksen
9.16.03


Short Term Memory Experiment


Self Recall Experiment


Experimental Subject Recall
In this experiment to test the short-term memory of an individual, I ran the procedure on a 56-year old male, a surprisingly enthusiastic subject who seemed motivated to score well (possibly in the hopes of combating a reputation for age-related memory loss).  The subject provided some excellent results, which turned out to be quite helpful in highlighting a few significant principles on the workings of short-term memory.  These specific data results are also reported in the table below. 

As is noted by the mean scores below, there was not much variation in my subject’s performance accuracy averages over the three recall categories of numbers, letters or words.  There was little divergence between the mean scores, which were 70.8%, 67.3%, and 71.4% for numbers, letters and words, respectively.  This holds consistent with the information provided by Ashcraft that recall for numbers and letters is relatively comparable, provided that they are presented in a similar fashion with no related meanings (Ashcraft, 1989, pg. 140)

Additionally, I found that this mini-experiment was a perfect example in practice of the “magical number seven, plus or minus two” rule originated by George Miller (1956).  The underlying significance of this principle shows a fundamental limitation of human memory, in that we as humans have a very finite amount of information that can be encoded, managed and maintained in our immediate memory stores.  The Miller rule specifies this limitation pretty directly in its name, that for the most part seven (give or take a couple) pieces of information can be received, process and remembered in this “bottleneck” area of short-term memory.  (Ashcraft, 1989, pg. 141)

In cases where there were seven or less pieces of data given, the subject managed to answer all correctly with perfect accuracy.  However as more information was added to the picture and the data strings became longer, the accuracy score of the subject did not increase in relation to this, and he did not seem to be capable of adding anything more to short-term memory.  Seven, plus or minus two, held true as the “magic” number in all unrelated trials.  I do have to qualify this point with the notion of unrelated trials however, because the subject was able to beat the rule however and correctly recall all 13 of 13 words in an instance.  In the final recall example in which 13 words were combined in a meaningful way to form a sentence, the subject recalled everything perfectly.  This is a predictable phenomenon in light of Miller’s principle of “chunking” or grouping information together to improve recall.  Numbers or letters that are grouped in some fashion so as to create a “richer, more complex” form or “chunk” of information, can be more readily encoded and recalled to memory.  (Ashcraft, 1989, pg. 142)  This made a great deal of sense on several levels.  First, the act of chunking or patterning smaller bits of information or digits (such as in a phone number) is helpful in condensing several items into one more meaningful chunk.  This single chunk holds more information, yet requires less space from short-term memory storage.  Additionally, the act of grouping information can be done in a semantically meaningful way, such as in a sentence, so as to give the listener information that can be easily made sense of and perhaps have more meaning through the mind’s understanding of the words as a phrase.

Thus, I think it can be concluded that some important information about short term memory is contained in the results of this experiment, and supports existing evidence about the way that the mind works to encode, maintain and retrieve information coming and going from this area of memory.


Subject Experimental Results 


Experiment Data

Subject Response

Subject Accuracy Score

870314

870314

6/6

71505436

7105436

7/8

2166872545

2168745

7/10

681437952470

2470695

7/12

284393482551

2843551

7/12

 

Mean Score:

70.8%

TSYLQP

TSYLQP

6/6

CIMWODXA

CIMWODXA

8/8

QWERTYUIP

QWERTYI

7/9

KWUCRALNYWGSJ

KWUCSW

6/13

LABONNEMAISON

LABONN

6/13


Mean Score:

67.3%

LEAF GIFT CAR FISH ROCK

LEAF GIFT CAR FISH ROCK

5/5

PAPER SEAT TIRE HORSE FILM BEACH TREE BRUSH

PAPER TIRE HORSE FISH BEACH ROCKS TIRE

7/8

BAG KEY BOOK WIRE BOX WHEEL BANANA FLOOR BAR PAD BLACK RADIO BOY

RADIO BOY PAD CAR

3/13

LOVE EMOTION PLAN ATTEMPT RULE LAW ANALYSIS SYSTEM FINE PAYMENT

LOVE EMOTION PLAN SYSTEM FINE PAYMENT LAW

7/10

WHILE I WAS WALKING THROUGH THE WOODS A RABBIT RAN ACROSS MY PATH

WHILE I WAS WALKING THROUGH THE WOODS A RABBIT RAN ACROSS MY PATH

13/13


Mean Score:

71.4


Ashcraft, M. (1989). Human Memory and Cognition (pp. 137-185). Scott, Foresman and Company: Glenview, IL

Miller, G. A. (1956). The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information. The Psychological Review, 63, 81-97