In this experiment, the cognitive approach was investigated, focusing on the study of memory within it.
Table of contents
PAGE
Introduction
Studies relevant to this investigation
2
Rationale
2
Aim
2
Hypothesis
2
Method
Method and design
3
Variables
3
Participants
3
Apparatus
3
Procedure
3
Controls
3
Results
Summary table
4
Commentary on summary table
4
Relationship to hypothesis
4
Graph commentary
4
Graph of results
5
Discussion
Validity
6
Improvements for validity
6
Reliability
6
Improving reliability
7
Generalisation of findings
7
Implications of the study
7
Application to everyday life
7
Reference
8
Bibliography
8
Appendices
List of appendices
8
Appendix 1: Standard instruction (word list included)
9
Appendix 2: Debriefing
0
Appendix 3: Raw data
1-25
Appendix 4: Calculations for all statistics
26
Introduction
In this experiment, the cognitive approach was investigated, focusing on the study of memory within it. Chunking, a technique used to extend short-term memory capacity was studied.
Miller (1956) suggested that we can hold 7±2 pieces of information in our short-term memory, which lasts for approximately 10-30 seconds. However, the amount of information stored in each unit or "chunk" varies. He proposed that STM would improve if long strings of information can be chunked into sections so that more can be stored. For example, the letters "m, e, m, o, r, y" can be chunked into the word "memory", reducing the number of chunks from six to one. Information would be also easier to retain when put into units that have more meaning to people, ex. FBI, BBC, CIA, etc.
Bower (1969) studied the difference in recall of the same words in 1, 2 and 3 word phrases. Results showed that organised material was learnt 2-3 times quicker than disorganised. Disorganised material took longer because people need time to identify the relationships between the words, while this would be already presented to them in the organised material. This shows people have natural mechanisms to chunk information into units to increase their learning capacities and that chunking of information into an organised structure aids recall of information.
Chase and Simon (1973) investigated the different chunking processes which novices and experts used in chess playing, building on Miller's "magical number" 7±2. They found that experts could identify relationships, like colour and proximity, between the pieces, creating chunks of 4-5 chess pieces. However, novices could only see each piece individually. This meant that while novices could only recall around 7 single-pieces, experts could recall up to 7 multi-piece chunks (more that 30 pieces in total). Therefore, chunking can greatly improve recall, and practice and development of skill levels also increase the ability to chunk information.
In a later study, Simon and Gilmartin (1973) guestimated that "grandmasters" could hold 50,000 chunks of chess pieces in their memories. Gobet (1998) developed on this research on chess expertise, investigating the number and size of the chunks that they can hold in their memories. He found that while the sizes of chunks vary accordingly to players' expertise, the average number of chunks that they could hold was 3 to 4.
Rationale
Past studies have shown results that chunking has improved memory recall. However, previous experiments tend to focus on organised information, which had meaning to people, like FBI, so it was very likely that recall would be from long-term memory storage and not STM. In this study, nonsensical letters will be used to test recall so that it is certain that information will be recalled from STM and not LTM. Participants of past studies also tend to be adults, so this study was conducted on students to explore a new age group.
Aim
The aim of this study is to investigate the effect chunking of letters has on short-term memory recall.
Hypothesis
There will be a significant difference between the results of the two conditions. Chunking of letters will improve memory recall of short-term memory: the number of correct letters recalled in the second condition will be greater.
Method
Method and design
This experiment was conducted using the experimental method. This was selected because it brings advantages such as the control of extraneous variables, which enables cause and effect to be established. Findings can also be repeated by others, increasing reliability of results. Participants were tested in two conditions, making it a repeated measures design. This is suitable because it eliminates the extraneous variable of differences in everyone's memories.
Variables
The independent variable was the way that the lists of letters used in the experiment were read out. In condition one, letters were read out one by one, with the same lengths of pauses between each one. In condition two, the letters were put into chunks of three and read out.
The dependent variable was the amount of material recalled in each condition. It was measured by comparing the number of correct letters that participants could recall.
Participants
The target population was Yr.12 students attending an international school in Hong Kong. They were selected through the opportunity sampling method, which is an efficient, convenient and less time-consuming method since participants were chosen by chance encounter in the common room where the majority of sixth formers gather. 15 Asian females, aged 16, were chosen to participate in the experiment. The same group of subjects participated in both conditions.
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The dependent variable was the amount of material recalled in each condition. It was measured by comparing the number of correct letters that participants could recall.
Participants
The target population was Yr.12 students attending an international school in Hong Kong. They were selected through the opportunity sampling method, which is an efficient, convenient and less time-consuming method since participants were chosen by chance encounter in the common room where the majority of sixth formers gather. 15 Asian females, aged 16, were chosen to participate in the experiment. The same group of subjects participated in both conditions.
Apparatus
The experiment was conducted in an empty, windowless classroom with the air-conditioning set at 25ºC. Participants were seated in seats fairly spaced out and facing the same direction to avoid any verbal or eye contact. A list of letters (see appendix 1) was read out for the test of recall in two conditions. Letters in condition one were read out one by one, with pauses in equal lengths between each letter. Letters in condition two were chunked into groups of three letters and read out with pauses of equal lengths between each chunk.
Procedure
. 1. Participants were selected and gathered in an empty classroom, to be tested as a group.
2. 2. A set of standardised instructions was read out to them (see appendix 1).
3. 3. Condition one: A list of letters (not chunked) was read out to participants who had to try and remember as many of them as possible in the same order.
4. 4. Participants were given two minutes to try and recall as many letters from the list-in the correct order.
5. 5. Condition two: After a five-minute break, participants were read a list of chunked letters and were told to remember as many of them as possible in the same order.
6. 6. Participants were given two minutes to try and recall as many letters from the list-in the correct order.
7. 7. Lastly, participants were debriefed (see appendix 2)
Controls
The same group of people was tested in both conditions. Students of the same age and sex, attending the same school in the same country were selected.
The repeated measures design was used so variations in people's memory abilities would not affect results. Order and boredom effects were reduced, with the five-minute break, so people will not remember the list of letters that was read out in condition one when tested in condition two. Letters were also read out back to front in the second condition so that it seemed to be a new list of letters, but was really still the same one.
Extraneous variables such as temperature and outside distractions were controlled. The temperature of the classroom in which the experiment was conducted was kept constant at 25ºC. The test was also conducted inside a windowless classroom, so subjects wouldn't be distracted by people and noise outside. The closed door kept the room relatively quiet and participants were told to complete the tests silently, eliminating another distraction.
A set of instructions read out before the start of the experiment dealt with ethical issues that may be related to this study, such as informed consent, deception and ability to withdraw. They were given the aim of the experiment and were given the option to withdraw at any time during the experiment. They all had to agree to take part in the tests before the experiment started as well and results were kept anonymous, abiding to ethical regulations for participant confidentiality.
Results
Summary Table
Summary table to show the differences between the memory scores of participants when they were given unchunked information and chunked information:
Subject
Memory score 1
(unchunked letters)
Memory score 2
(chunked letters)
Difference
6
6
0
2
4
7
3
3
1
6
- 5
4
4
6
2
5
8
7
- 1
6
3
8
5
7
3
5
2
8
2
9
6
5
- 1
0
4
4
0
1
7
5
- 2
2
6
7
3
9
0
4
8
2
4
5
6
6
0
Total
96
06
0
Mean
6.4
7.07
0.667
Median
6
6
Mode
6
6
0 and 1
Standard deviation
3.22
2.88
2.39
Commentary on summary table
As shown in the table above, the total number of letters recalled in condition two was significantly higher than that of condition one, with a difference of 10. Also, 11 out of the 15 participants showed an improvement in recall in condition two. However, the mean of the totals showed a much smaller difference between the two conditions: only 0.667 and the mode and median scores are the same in the two conditions. This was a caused by the outstanding results of subjects 3, 10 and 13, which made the overall ranges of results more dispersed, and so amplified the difference between results of the two conditions.
Relationship of results to the hypothesis
The hypothesis of this experiment was that chunking of letters will improve recall in STM.
Results showed that cause and effect could not be established between the IV and DV. Chunking did not improve recall in this experiment significantly, even though the total number of letters recalled in the second condition was 10 more than that of the first condition, which suggested there was a big difference. However, the median and mode calculated from the results were the same, so in actual fact the majority of participants' recall did not change much, but due to certain individual's memory change, the results became more dispersed, causing the difference in the two conditions to appear much bigger. The mean also supports this as it showed that, on average, each person only improved recall by 0.667 (3s.f.) words.
Graph commentary
The graph on the following page illustrates the difference between the totals and other descriptive statistics calculated from the results. The difference between the totals was 10% greater than the difference between the means, medians and modes of the two conditions.
Graph of results:
Discussion
Validity
Validity refers to the "trueness" of an experiment to what its intended aim was-whether it measured what it was supposed to measure.
One aspect of this is internal validity, which assesses the extent to which manipulation of a variable in the experiment (IV) was able to do its intended job (change the DV). This includes the control of extraneous variables so cause and effect can be established between the IV and the DV. There was internal validity because confounding variables from external factors, ex. distractions and temperature were controlled so it was certain that changes in the DV were caused solely by the IV.
Experimenter bias was eliminated because participants were not affected by any special behaviour in the experimenter's part. All letters were read out in the same tone so that there were no specific emphases on particular letters to affect recall. However, there may have been problems in demand characteristics as it was clear that the experiment was conducted to assess participants' memory. They may have deliberately "forgot" letters read out in an attempt to disrupt the experiment. Certain participants were also familiar with the theory of chunking to aid STM recall as they also study psychology, which may have affected results.
The experiment also had construct validity as the method used to measuring STM recall was able to measure what it claimed to. Results showed differences in recall quantitatively, which can be compared.
External validity, or ecological validity (EV), is a measure of how well results can be applied to realistic situations. This experiment had EV as it was conducted in a classroom in which students would attend their lessons normally. However, it also lacked EV in other aspects, such as the total elimination of external distractions, as rarely are lessons taught completely in silence. The usage of letters in the experiment to investigate STM storage was also unrealistic, as people do not memorize lists of letters daily.
Improvements for validity
To improve the validity of this experiment, demand characteristics must be reduced. Teachers may have been asked to conduct the experiment as a task set during lessons. This would also improve EV, as it is more realistic for students to be "learning" information in their lessons rather than under artificial conditions.
Different information could also be given to participants for them to memorise instead of letters. For example, words can be used, which can be chunked into sentences for condition two. This improves EV as words and sentences are used commonly in everyday life, unlike meaningless strings of letters. The usage of numbers would also make the experiment more realistic, as numbers are often chunked into phone number or combination lock codes. However, some people may be more familiar with certain number combinations and so remember them better.
This experiment could also have been conducted as a field experiment since it would then take place under natural settings. Participants could be asked to memorise lists of items in a grocery list; unchunked in the first condition and then chunked under different headings in the second. However, it would be difficult to find participants to take part and may still be unnatural to ask them to memorise word lists.
Reliability
Reliability measures consistency in results: whether or not it can be repeated by another researcher afterwards.
There was external reliability as many aspects of the experiment were controlled, making it easier to repeat. The same method was used to measure recall in both conditions so comparisons could be made accurately between results. Procedures and instructions used were standardised, so they can be used again and again in other experiments. The apparatus and controls of confounding variables used were very basic and could be duplicated in many other locations. However, the sample used in this experiment may be harder to repeat in different locations as it was from a very small target population. Participants have to be from an international school in Hong Kong so it cannot be repeated in other countries or in public schools in Hong Kong.
It also lacked internal reliability, as memory is a very subjective thing. We cannot go inside someone's head to read their thoughts and look through their memories. Therefore, it cannot be certain that results showed exactly what participants remembered, as they may leave out some information deliberately.
Improving reliability
This could be improved by increasing the sample size. More participants could be used so results are more representative of the target population, ex. using a sample of 50. However, the process of collecting data with such a big sample becomes more difficult, as it would be hard to control them and make them do the experiment in absolute silence.
Order effects, such as boredom effect, could also be eliminated by using an independent group design, also known as "split-half technique". Half of the participants selected would take part in condition one, while the second half takes part in condition two, and then results of the two groups are compared. However, people's memories vary so it would not be accurate to compare two different people's results.
Generalisation of findings
The target population of this experiment was Year 12 students attending an international school in Hong Kong, from which a sample of 15 females aged 16, were selected to become participants.
Results can only be generalised to half of the target population, as only females were selected to take part, leaving out the male half of the population. They cannot be generalised beyond the target population either, as it was very small: participants were of the same gender, same age, from the same school and same city. Results cannot be generalised to other cities and countries in the world or even to the population of this school, as only one age and sex group was studied.
To improve the generalisation of results, participants could have been chosen from both sexes of the target population. Moreover, the target population also needs to be bigger, with participants chosen from different schools, in different places of the world and of different age groups.
Implications of the study
Results of this experiment supported the theory of chunking. In the first condition, 15 letters were read out as 15 separate units, which is over the "7(2" limit of STM suggested by Miller. However, when chunked into 5 units of 3, recall improved, as shown by the improvement of recall of the majority of participants' results. This also supported Bower's theory, which states that chunking of information aids STM storage and recall.
This experiment can be extended to investigate the theory of expert chess players having better chunking abilities than novice players-suggested by Chase and Simon (1973). They proposed that experience with chunking led to better abilities in this area. STM of expert chess players can be compared to the general population to find any differences.
Application to everyday life
Results show that chunking improves STM recall.
This can be applied to the recall of numbers such as security codes and phone numbers. Short codes can be chunked into one unit, although longer series of numbers like phone numbers may be chunked into two or three sections.
Grocery lists can also be chunked. Items of a similar nature can be chunked together into a group, ex, carrots, lettuce and peas could be chunked into a "vegetables" group, so that they can be remembered as one chunk rather than three separate units.
Storage of new information learnt in school, before it is stored in long-term memory can also be chunked, as the amount of each chunk can be very big. For example, information about external and internal validity could be chunked under "validity".
References
Bower, G. H. (1972a). Perceptual groups as coding units in immediate memory. Proceedings of the Psychonomic Society, 27(4), 217-219.
Bower, G. H., & Winzenz, D. (1969). Group structure coding and memory for digit series. Journal of Experimental Psychology Monographs, 80, 17.
Miller, G.A (1956). The magical number seven, plus or minus two: Some limits in our capacity for processing information. Psychological review, 61, 81-97
Chase, W. G., & Simon, H. A. (1973). Perception in chess. Cognitive Psychology, 4, 55-81
Chase, W. G., & Simon, H. A. (1973). The mind's eye in chess. In W. G. Chase (Ed.), Visual Information Processing. New York: Academic Press. (pp. 215-281).
Gobet, F. (1998). Memory for the meaningless: How chunks help. Proceedings of the Twentieth Meeting of the Cognitive Science Society. (pp. 398-403). Mahwah, NJ: Erlbaum.
Gobet, F., & Simon, H. A. (1998). Expert chess memory: Revisiting the chunking hypothesis. Memory, 6, 225-255.
Gobet, F., & Simon, H. A. (in press). Five seconds or sixty? Presentation time in expert memory. Cognitive Science.
Simon, H. A. (1974). How big is a chunk? Science, 183, 482-488.
Simon, H. A., & Gilmartin, K. J. (1979). A simulation of memory for chess positions. Cognitive Psychology, 1973, 5, 29-46. Reprinted in H. A. Simon (Ed.), Models of thought. New Haven, CT: Yale University Press.
Bibliography
Angles on Psychology, Matt Jarvis, Julia Russell, Cara Flanagan, Larry Dolan, 2000, Stanley Thornes Ltd.
http://soeweb.syr.edu/faculty/pldought/ide633/CognitivePsych.ppt
http://www.cs.duke.edu/~cig/cps170/notes/jan30/JAN30.htm
http://www.garysturt.free-online.co.uk/forget.htm
http://www.hfac.gmu.edu/~gray/courses/Psyc530/fall01/downloads/1st_symposium/Gobet_ICCM-2001.pdf
http://www.mtsu.edu/~sbernst/404/Lecture5.htm
http://www.psychology.nottingham.ac.uk/staff/Fernand.Gobet/preprints/Cowan_commentary.doc
http://www.ship.edu/~ambart/PSY_325/stm.htm
http://www.pigeon.psy.tufts.edu/avc/terrace/default.htm
Appendices
Appendix 1: Standard instruction (word list included)
Appendix 2: Debriefing
Appendix 3: Raw data
Appendix 4: Calculations for all statistics
Appendix 1: Standard instructions
Read out the following instructions to participants from the front of the room.
Do not read out those in italics as they are instructions for the experimenter and/or the assistant(s).
Thank you for coming to take part in this psychology experiment.
Before we start, I would like to inform you that if you wish to withdraw now or at any point during this experiment you may do so.
Please carry out this experiment in silence and do not disturb out participants.
If you have any questions please ask now.
(Give out pens and paper to participants)
I am going to read out a list of 15 letters.
Listen carefully, in silence, and try to remember them in the right order
(Read list of words, signifies a two second pause)
Q T N F D L S Z U H Y G A C P
You now have two minutes to write down as many letters in the right order as you can from the list
(Two minutes later) Please stop writing and put your pens down
We will now have a five-minute break
(Five minutes later) I am going to read out another list of 15 letters.
Listen carefully, in silence, and try to remember them in the right order
(Read list of words, signifies a two second pause)
Q T N F D L S Z U H Y G A C P
You now have two minutes to write down as many letters in the right order as you can from the list
(Two minutes later) Please stop writing and put your pens down
Thank you for participating in this experiment. Results of this experiment will be used for research purposes only and your names will be kept anonymous to ensure participant confidentiality.
Please leave the pen and paper on the table. This experiment has fully ended. You may leave. Thank you
Appendix 2: Debriefing
Thank you for participating in this experiment.
You have just participated in an experiment investigating the effects chunking has on information recall of the short term memory
You may cancel your results if you wish to.
If you have any queries about this experiment or wish to gain further information about this study, you are welcome to ask me.
Good bye. Have a nice day.
Appendix 3: Raw data
Appendix 4: Calculations for all statistics
