Chapter 1. Brown-Peterson

1.1 Introduction

Cognitive Tool Kit
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Brown-Peterson

You are in your first day of class, in a room full of people you don't know. The teacher has the students say what their names are. Each person takes a few seconds to say his/her name and then the next person says his/her name. After all of the students have said their names, how many do you really remember? I know I remember very few. Memories from our short-term (also known as "working memory") fade; the question here is, how quickly do they fade?

1.2 Experiment Setup

1.3 Instructions

Instructions

You need to follow these directions carefully for this experiment to work.

You will need to press the space bar to begin the experiment. At the beginning of each trial, a fixation mark will appear. Please look at this mark. After a brief delay, you will see three letters with a three-digit number right below. Your goal is to remember the three letters, but it is also necessary to note the number.

After the letters and numbers are removed, there will be an intervening period, or delay, before you are asked to recall the letters. Immediately start counting backward by threes out loud as fast as you can, starting from the displayed number. If you lose track or forget the number, pick a different number and start over. It is vital that you do this task as quickly as you can. There will be a beeping tone to indicate how fast you should try to count. Do your best to keep up. In no case should you stop. At the same time, there will be a dot on the screen and a box. Move your mouse to track the dot. For this experiment to work, it is vital for you to be completely engaged in these intervening tasks.

At the end of the intervening period, the word “Recall” will display on the screen. Type, in order, the letters you recall and then press enter to begin the next trial.

1.4 Experiment

Begin Experiment

1.5 Results

Results

1.6 Debriefing

Debriefing

This experiment examines what is often called short-term or working memory. This type of memory holds information to be used in the current moment. These are the memories of which you are currently aware. Recalling the example from the introduction of students saying their names one after another, we are well aware that memories held in short-term memory fade.

This experiment, based on a pair of experiments done almost at the same time by Brown (1958) and the husband and wife team Peterson & Peterson (1958), was designed to explore this fading of information from our short-term memory. Let us examine a few important features of this experiment.

  1. You only have a small item to recall, three consonants (CCC) or a consonant-vowel-consonant item (CVC). The point of this aspect is to avoid over-burdening your short-term memory. Other experiments, such as the memory span experiment in this set of experiments, help us realize that we do not hold many items in our short-term memory.
  2. You were not free to just hold the items in memory. If you were just left to remember an item during a blank period, you would not just sit there with an empty mind doing nothing to the item you were trying to remember. At the least, you would repeat the item to yourself. That repeating, a form of a behavior called rehearsal, can help keep the item in your short-term memory and keep it from fading. In this experiment, during the delay, you were asked simultaneously count backward by threes and track an object. Peterson & Peterson (1959) used the counting task. The point of these tasks is to prevent you from doing rehearsal during the interval, thus allowing the item to fade if it will. The beeping to pace the counting backwards by threes makes you concentrate on the counting task so that you will not have time to repeat the three letters to yourself between the items.

The results from Brown (1958) and Peterson & Peterson (1959) demonstrated that items do fade from our short-term memory, and fade quickly. One of the implications of this finding is that we have to do some form of rehearsal to transfer information from short-term memory to long-term memory.

References:

Brown, J. (1958). Some tests of the decay theory of immediate memory. The Quarterly Journal of Experimental Psychology, 1012-21.

Peterson, L., & Peterson, M. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58(3), 193-198.

1.7 Quiz

Quiz

Question 1.1

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1
Incorrect.
Correct.
The independent variable is the value that is changed by the experimenter. In this case, the delay between the presentation of the letter string and when you can recall it was varied, so the correct answer is the delay.

Question 1.2

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1
Correct.
Incorrect.
The dependent variable is the value that the experimenter collects to indicate how you performed in the experiment. In this case, we determined how many letters you typed in the correct position. So the correct answer is the percent correct.

Question 1.3

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1
Correct.
Incorrect.
This experiment examined how items are held in memory for a brief period so they can be used. This is a form of short-term memory.

Question 1.4

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Correct.
Incorrect.
If you wish to remember something, you will tend to repeat it to yourself. This behavior is called maintenance rehearsal. Since this experiment is designed to examine how memory fades from short-term memory, this rehearsal had to be prevented. The correct answer is to prevent you from rehearsing the letters.

Question 1.5

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Correct.
Incorrect.
The standard experiment results, as indicated by the graph, find that most items are gone within 15-20 seconds, making this option the correct answer.