Running head: SERIAL POSITION
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Serial Position
Jeremy Vall
California State University, Fullerton
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Abstract
While short-term memory can typically hold up to 7 items for about 30 seconds, control
processes are techniques that we use to retain a maximal amount of information.
However, previous research shows us that in free recall experiments, the serial position of
items on a list is an important factor in what we are able to recall (Serial Position, 2010).
The primacy and recency effect describe our tendency to recall items in the beginning
and end of a sequence better than items in the middle of the sequence. In this experiment,
participants were shown a sequence of 10 letters and then asked to recall the letters that
were shown, in any order, as best they could. The findings confirmed the hypothesis that
participants, on average, did a much better job recalling the letters in the beginning and
end of the sequence than the letters in the middle.
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Serial Position
Atkinson and Shiffrin’s modal model of memory made great advancements in
today’s modern understanding of memory processing. The modal model consists of three
features that are sensory memory, short-term memory, and long-term memory. As
sensory receptors collect information, we use control processes such as rehearsal to help
maintain information in our short-term memory for about 30 seconds. The more control
processes we use the better chance we have at encoding information into our long-term
memory (Goldstein, 2007). While there are various techniques we use to remember
pieces of information, our short-term memory is limited to remembering approximately
seven items.
Previous research has looked at the effect that the serial position of items have on
memory retrieval. When given a sequence of items to remember it has been widely
documented that people are more likely to recall the first few items presented in the
sequence and the last few items on the sequence much more frequently than the items
that fall in the middle of the sequence. The primacy effect refers to our tendency to
remember the first items in the sequence and the recency effect refers to our tendency to
remember the last items in the sequence (Serial Position, 2010).
The current study exposes the participant to a sequence of 10 letters, each shown
for one second. After each sequence, the participant is instructed to recall all the letters in
the sequence in any order. Keeping the primacy and recency effects on memory in mind,
we hypothesize that in the Serial Position experiment, participants will recall the first and
last items in the sequence more frequently than the items in the middle of the sequence.
The dependent variable being measured in this experiment is the average of correct
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responses depending on the three levels of the independent variable, first items, middle
items, and last items. The first three letters will be grouped as the first items, the next four
letters will be grouped as the middle items, and the last 3 items will be grouped as the last
items.
Method
Participants
The data gathered consisted of 67 California State University, Fullerton
undergraduate psychology students enrolled in Professor Westbrook’s cognitive
psychology lab. Demographics of participants were not formally surveyed; however,
students come from a wide spectrum of different backgrounds and cultures. Participation
in the experiment was part of a classroom assignment that counted as credit to their
course grade.
Materials
The material used in the study was the serial position activity found on the
CogLab 2.0 program using DELL computers that were provided by the university. The
program was run via internet on Mozilla Firefox, Internet Explorer, or Google Chrome
web browsers. The program included a virtual keypad for participants to choose their
answers for each trial. The stimuli consisted of a series of ten random letters which were
to be recalled at the end of each series. All participants completed the experiment in a
quiet, ventilated lab on campus.
Procedure
Before the task, participants were introduced with background information
relating to serial position and memory and instructed on how the experiment would be
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administered. There would be a total of 15 trials. Each trial would flash a sequence of 10
letters individually, each letter lasting the duration of one second. At the end of each trial,
the participant was to select the letters they recalled from the sequence in a virtual
keypad, in no particular order. The participant could then click the “Next Trial” button to
begin the next trial.
Results
The results were measured across participants in the class. The average percent of
correct recalls across the 15 trials per position is charted on Table A1. The three levels of
the independent variable we measured: beginning, middle and end of the list (Table A2).
The standard deviations, of correct responses per position were measured across
participants (see Table A3). For the beginning positions (M = 77.29, SD = 14.51), middle
positions (M = 65.28, SD = 18.40), end positions (M = 68.17, SD = 20.29). As predicted,
on average participants in class did better recalling the letters that were in the beginning
and end positions of the sequence than the letters that were in the middle positions of the
sequence.
Discussion
The data confirmed the hypothesis that participants would recall the letters falling
in the beginning and end of the sequence with a greater frequency than the items in the
middle of the sequence. The results support the idea that the order in which we are given
information is an important factor of what we will remember. It appears that in this
experiment that the primacy has an especially significant effect. Perhaps this is due to the
design of the test favoring the primacy effect. The standard deviations increased as the
position of the letter fell further in the list. This means that most participants did well
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recalling the first items while there was more variance of correct and incorrect answers
for items that fell toward the end of the list. Future research can focus on the effect on
long-term memory. Perhaps research can be done in a college setting where students are
given multiple chapters of information to study for a test. One could hypothesize that the
students will do better in the sections that they studied first and last on the test. Other
research can look at the practical applications of these findings. It would be interesting to
see if serial position matters when it comes to job interviews. Would applicants who
interview first or last have a better shot a getting a job than an applicant who may be
forgotten because they were interviewed in the middle? While previous research already
shows these effects, this data reinforces the view that serial position does play a role in
memory.
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References
Goldstein, E. (2007). Cognitive psychology connecting mind, research, and everyday
experience, (2nd ed.) Belmont, CA: Thomson Wadsworth.
Serial Position. (2010). Cog Lab (version 2.0) Available from
http://www.coglab.wadsworth.com
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Appendix
Table A1.
Average of correctly recalled letters across participants per position in sequence.
Position in list
Percent correct
1.0
81.242935
2.0
77.74011
3.0
72.881355
4.0
69.15254
5.0
65.9887
6.0
62.59887
7.0
63.38983
8.0
65.08475
9.0
70.282486
10.0
69.15254
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Table A2.
Average of correctly recalled letters across participants per categorical position in
sequence.
Categorical Position in list
Percent correct
Beginning
77.29
Middle
65.28
End
68.17
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Table A3.
Categorical standard deviations across participants
Categorical position in list
Percent correct
Beginning
14.51
Middle
18.40
End
20.29