Atkinson and Shiffrin believed that ‘chunks’ of information received by the sensory store could be held in the STM for around 20 seconds, but only 5 to 9 (on average) chunks of info can be remembered without rehearsal. However, if rehearsed the chunks of information can be transferred into the long term memory and more items can be remembered. The theory of the rehearsal loop interests me, so I decided to look further into it and found that psychologists: Brown (1958) and Peterson and Peterson (1959) independently discovered a method for testing the existence of the rehearsal loop called the Brown-Peterson technique. This basically involves a list of trigrams (three letter words made up of consonants with no immediate meaning ie. BKD, as apposed to WHY) shown to subjects for 20 seconds, rehearsed for 25 seconds and then recorded in order by the subject as well as possible. The same list is then shown to another subject for the same amount of time, however this time the 25 seconds rehearsal time will be interrupted with an interference task ie. counting backwards in threes from the number 58. This is the technique I will use as a basis of my mini-cognitive research project.
AIM:
To test the existence of the rehearsal loop by preventing it from its task with an interference task during the rehearsal time.
RATIONALE:
I will be re-creating the Brown-Peterson technique for testing the existence of the rehearsal loop, although my study will use slightly different trigrams, and obviously a different set of people. I’m interested to check whether the results of my study will support the results found by Brown-Peterson or not. I will use a set word list for both groups of people studied and I’m expecting the results of my study to support the results of previous tests, thus supporting the theory of existence of the rehearsal loop.
HYPOTHESIS:
When asked to recall the list of trigrams in order after a period of 25 seconds rehearsal time, the subject will remember significantly more trigrams if the rehearsal time is not interrupted by an interference task.
NULL HYPOTHESIS:
Subjects taking part in the experiment will not recall a significantly greater number of words whether their rehearsal time is interrupted with an interference task or not. Any difference found is purely down to chance.
METHOD:
The method I chose to use in order to obtain the clearest and most reliable data was the laboratory experiment. The reason for using this method is to reduce the amount of extraneous and possibly confounding variables which could interfere with the results; also it becomes very easy to repeat the same test over and over without change. I will use the independent groups design to ensure that different participants are used for each test in order to avoid the chances that the participants will skew the results through rehearsal.
The first set of participants will be shown a list of 15 trigrams for 20 seconds, after which time they will be asked to rehearse these for a period of 25 seconds. After that time they will then be asked to write out as many as possible in the correct order (if the trigram is BHD then the participant must write BHD, no mark will be given for BDH). The results will then be recorded.
The same set of trigrams will then be shown to a different set of participants for the same amount of time. This time however during the 25 seconds rehearsal time, the participants will be asked to perform an interference task, which will be counting backwards in sets of 4 from the number 295. After the 25 seconds, they too will be asked to recall the trigram list and their results will also be recorded.
ETHICAL ISSUES:
Each participant will be fully aware of the test that he/she is to be involved in, and they will be asked for their consent before any psychological testing begins.
Each participant will have the right to withdraw at any point during the experiment.
No deception will be necessary for the experiment.
Each participant has the right to confidentiality, and anyone who wishes the data from their particular part of the experiment to be destroyed and not published also has that right.
All participants will be debriefed afterwards and their results explained to them.
The chosen population I chose to sample was Aylesbury College students aged between 18-39 and used the opportunity method of sampling from the chosen target population in order to obtain a sufficient amount of participants as this was fair way to obtain a good mix, and also to test the participants at their own convenience. I tested 30 participants altogether, 11 females, and 19 males for this experiment. The experiment took place in a quiet area of the library at the convenience of each participant. I explained the task in hand to each participant before they started in order to clear up any confusion during the test which could affect the amount of trigrams remembered. I provided each participant with a pencil, a piece of paper and the list of trigrams which was covered by a piece of card. 15 of the participants had no interference task to complete during the 25 seconds rehearsal time, and 15 did have the interference task. The amount of time in which they had to study the list, as well as the amount of time they had to rehearse the list was adjudicated by myself with a stopwatch for more precise timing. After each participant had finished their test they were debriefed in full and their results shown and explained to them.
RESULTS:
Below is the table of results gained from the first experiment carried out with 15 participants who were asked to recall trigrams from the list without an interference task to perform during the rehearsal period. The participant’s details have been kept confidential and replaced by a participant number, and their results record
The table below shows the results of the next 15 participants who were asked to recall trigrams from the same list, however during their rehearsal time they were asked to perform the task of counting backwards in sets of 4 from 295.
Below is a list of the trigrams used and the results of both tests in numerical format to show specifically which trigrams were remembered, and how many times, which is not necessarily important to the proving of my hypothesis, however it could be useful for the conclusion to explain why certain trigrams were remembered.
RESULTS IN GRAPHIC FORM:
EXPLANATION OF RESULTS:
As you can see in Figure 1.2 the results had a range from 2-7 in the amount of trigrams remembered, making the range: 5, and the mean result from the first set of experiments was: 4.87 Trigrams remembered. Whereas in the second experiment, where the results can be seen in Figure 1.3, it clearly show a big difference in both the range and the mean, the range being: 2 and the mean being: 2.07 . These results support my hypothesis in proving that the results are significantly changed when an interference task is introduced during the rehearsal time.
Figures 1.5, 1.6, and 1.7 are bar charts which show the results in graphic form and make it easier to see a difference in the two variations of the experiment. Figure 1.7 shows the results especially well as even though the results are from different participants, when seen side by side you can see that they are similar in the way that there are a lot of consistent results ie. 6 remembered trigrams in the first set of participants test, and 2 remembered trigrams for the second set of participants test, however there are a couple of results which stand out above or below the rest, and I will look at these in more detail in my conclusion.
CONCLUSION:
In conclusion to this experiment, I found that the results did support the theory of the rehearsal loop, its existence and its ability to help people remembered more when it is not interfered with by another task. I therefore agree with my original hypothesis, however some results did show another sort of pattern which links into another area of the multi-store model theory, and also the levels of processing theory and we can see these patterns in Figure 1.4.
In this table we can see that there are a few different trigrams which stood out from the rest as the most remembered, especially in the non-interference column, those being XTL, GZR, NHT, and RST. Now this could purely be chance, however there are other explanations offered in the theories I mentioned, for example the trigrams might have an un-intentional semantic meaning, for example with NHT, a participant may have remembered it better because it reminds them of the word NIGHT, or GZR may have been better remembered by males in the test because it’s also a type of motorbike and this may have caused strong imagery in the participants helping them to remember it better. Another possible theory is primary recency effect, part of the multistore model. This theory says that words in a list are better remembered from the start and the end of a list, as the first word is supposedly the most rehearsed, and the last word, is the most recently seen, or heard. This research does also support that theory as XTL was one of the most remembered trigrams, as was RST, which were the first and last trigrams in the list, however as the list was not read out acoustically this could be down to chance, as it would rely on the participant reading the list from start to finish. These two trigrams may have simply stood out from the rest because there were no trigrams above XTL, and none below RST.
I am extremely content with the finding from this project, as it was very interesting to prove that un-interrupted rehearsal time really can affect the amount of retained information in the LTM, and will definitely help me personally in revision tasks and exercises in the future.
RECOMMENDATIONS:
If this test were to be repeated and I had to make any recommendations from what I have learnt, I would suggest to the experimenter that a quite private room was found in order to keep the full attention of the participants. In my experience I found that during one or two of the tests the participants may have been slightly distracted by other students in the library, which could have affected the results in a negative way. This may in turn affect the ecological validity of the test in a negative way, however it is also supposed to be a type of mini exam, and therefore applying exam like conditions could be seen to increase the ecological validity.
Another suggestion would be to increase both the study time that the participant has initially and also the rehearsal time for both sets of tests, to distinguish whether that also has more of an affect, either more positively for the non-interference tests, more negatively for the interference tests, or both in fact.
And finally, I would suggest using a larger sample of the chosen target population in order to get a clearer idea and more conclusive results.
Although the results I achieved did prove to support the hypothesis and the theory, I feel as though with the alterations to the experiment that I have listed, I could have achieved a more definitive set of results and possibly shown better evidence that the rehearsal loop exists.
Bibliography
Coolican, H. (1996). Applied Psychology. London: Hodder and Stoughton.
Lisney, M. (1989). Psychology, Experiments, investigations, and practicals. OXFORD: Basil Blackwell.
M Cardwell, C. F. (2003). Pschology AS, The Complete Companion. Cheltenham: Nelson Thornes LTD.
Tayler, I. (1999). Active Psychology. Harlow: Pearson Education LTD.
