To test if preventing the rehearsal loop by an interference task reduces the number of words recalled from a list, hence a wider aim is testing the existence of short-term memory.

Psychology coursework

Introduction

Background

The multi-store model of memory is concerned with the cognitive area of psychology. It suggests that memory is dived up into different stores, sensory, short term and long-term; it was identified by Atkinson and Shiffrin (1968).

The short-term memory is believed to be able to hold about seven “bits” or chunks of information for about 20 seconds without rehearsal. This information will move into the long-term memory if the information is repeated or rehearsed. In the diagram above it demonstrates how the rehearsal loop will send the information back around into the short term memory this will eventually go on into the long term memory.

Glazner and Cunitz (1966) were interested and studied the primacy-recency effect. They also wondered if it made sense to consider the short and long term memory as two different stores. They then conducted experiments to see if they could independently manipulate the short and long-term memory. They conducted experiments of free recall with a list of words this lead them to the primacy and recency effect and the serial position curve (a U shaped graph) which shows how people tend to remember more words from the beginning and end of a list.

The primacy effect is remembering the early words in the list; this is because they have had time for rehearsal, and the recency effect is remembering words from later in the list because they have remained in the short-term memory. They then altered their experiment and introduced an interference task designed to prevent the participant from rehearsing and therefore preventing words being stored in the short-term memory. There have been many developments on this research but a particularly profound discovery was by Murdock (1961) he found that the number of words a participant recalled could be increased by chunking the letters into groups of three he called these “trigrams”.

Rationale

In the experiment the rationale was to replicate the study by Glanzer and Cunitz (1966) which found that delaying recall of a list of 30 words destroyed the recency effect, or short term memory, therefore resulting in words from the last third of the word list being forgotten. The rationale for the interference task is Brown and Peterson (1958) rehearsal prevention task where they asked participants to count down in three’s from a given number. They found that forgetting occurred after 18 seconds

Aim

To test if preventing the rehearsal loop by an interference task reduces the number of words recalled from a list, hence a wider aim is testing the existence of short-term memory.

Hypotheses

In a free recall experiment of remembering words from a list of 30 for 40 seconds after being read there will be more words recalled from the last third of the list if recall is immediate. Whereas there will be less words recalled from the last third if a 40 second interference task of counting down from 57 in 3’s is introduced before free recall.

Method

Method and design

The method chosen was a field experiment using a matched pairs design. The experiment was conducted in the same setting the participants would usually work and under the same conditions. Using a field experiment allows comparisons between two groups the experimental and the control group it also has the advantage of high ecological validity whereas if conducted within a laboratory instead of the normal classroom then the participants may not perform as they would have normally. A matched pairs design attempts to match people in one group with a similar person in another therefore it can control the individual differences of the participants rather that the entire group and prevent confounding and extraneous variables from occurring. A matched pair design also prevents demand characteristics and order effects taking place. The order effects are practice, fatigue and boredom these occur when a repeated measure design is used. For example if the experiment was conducted several times people may get bored or fatigued and there performance would fall however they could also have had enough practice to improve their results. Also demand characteristics in this experiment would arise because people would eventually learn the words and know what to write down making the results inaccurate

Variables

The independent variable in the experiment is whether or not the group was given an interference task or not. The interference task was to count down in three’s from 57 for 40 seconds after the word list was read.

The dependant variable in the experiment was the number of words recalled in free recall from the list in 40 seconds.

Participants

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Variables

The dependant variable in the experiment was the number of words recalled in free recall from the list in 40 seconds.

Participants

The participants were divided into 2 groups using an opportunity design method. The opportunity sample has the disadvantage of being a biased sample that is not representative of the entire population. The opportunity sample was a class of 6th form psychology students both with equal amounts of males and females and they were also divided equally between the two groups depending on their ability, which was taken from GCSE results this was done by using the matched pairs design. Group A was the control group and Group B was the experimental group

Apparatus

Room ~ where the experiment can be conducted
Pens ~ to write the recalled words

Paper ~ used to record the recalled words onto, two colours used, orange and blue, to prevent results from becoming mixed
Tables ~ used to lean on while recording the recalled words
Chairs ~ to sit on while recording recalled words
Stop watch ~ used to record the reading time, recall time and for the experimental group the interference task time.

Procedure

The entire sample was chosen by opportunity sampling. The experiment begins in the classroom where the experiment is to take place the room is laid out with the reader at the front and all participants facing the reader. They are then briefed on the experiment and read the following statement.

“You are about to take part in an experiment testing whether or not an interference task will effect the amount of words recalled from a list of 30 words in free recall. You have the right to withdraw from the experiment at any time and your results will not be used. All results are confidential and anonymous.”

The participants then had to give consent to participate in the experiment. Once this passage has been read then group B, which was also chosen using an opportunity sample, is sent outside the room to wait while the group A remains in the classroom. Group A is the control group. They are seated around the room at a table where they are given a piece of blue paper and a pen (see appendix for word list). The words were read at 1 word per second for 30 seconds until all 30 words were read then group A were straight away given 40 seconds to recall the as many words as they could in any order they remembered them. After 40 seconds they were asked to put down their pens and then the reader collected in the blue pieces of paper. They were then asked to leave the room and group B to come in and sit in the same seats used previously and were then each given a piece of orange paper each and a pen. Then from the same place in the room as for group A the reader read the list of 30 words again at the same pace. After they were then told to count backwards from 57 in 3’s for 30 seconds. Once the 30 seconds was up the participants were given 40 seconds to record as many results as they could in any order they remembered them. After the 40 seconds group B was told to put down the pens then leave the room. Then the orange pieces of paper were collected up. After the pieces of paper were collected the participants were all brought back to the classroom and debriefed on the experiment.

Controls

Before the list was read to the participants they were briefed on the experiment.
For each group the same reader read 1 word per second for 30 seconds in order to ensure both group have an equal amount of time to remember words.
Both groups had 40 seconds for free recall to ensure both group have the same length of time to recall words.
Same list of words was read in same order in order to ensure experimental validity.
Conducted within 5 minutes of each other to prevent one group from having the disadvantage of being more tired or less alert.
Conducted under same weather conditions to ensure both groups’ moods are not affected by the weather
Reader read the word list from the same position in the room to ensure the readers voice is projected around the room in the same way for both groups
Reader attempted to read the word list at the same volume and clearly to prevent the chance of misunderstanding a word that was read out.

The reason that the above controls were used was to try and increase the accuracy of the results and to eliminate extraneous and confounding variables.

Results

Summary table

Words recalled and position they occurred in the list that was read out

Table commentary

Mean, median, mode and range of correct words recalled

From the above tables we can deduce several things:

Group A remembered more words than group B.
The mean amount of words for group A was higher than the mean amount of words for group B.
For both group A and B the most words were remembered in the first third.
For group A the words recalled in the first third were highest then lowest in the second third and then higher in the last third.
Whereas for group B the words recalled were highest in the first third lower in the second third and lowest in the last third.

Commentary

From the graphs we can see that:

from graph 1 we can see that group A remembered more words in both the first and the last third compared to group B
the trend for the amount of words recalled by group B decreases faster than the trend for the amount of words recalled by group A
From graph 4 we can see that the most percentage of words remembered was in the first third was higher than the amount remembered in the second and last third but the second third had the least percentage of words recalled
From graph 5 we can see that the most percentage of words remembered was in the first third and then the next highest was the second third and the lowest was the last third.

Relationship to hypothesis

In general we can see that the results from group A show the primacy receny effect in action because more words were remembered from the first and last third of the list. This supports my hypothesis. Also we can see from the results of group B that the amount of words recalled in the last third was higher than the second and last third showing the primacy effect however the last third was the lowest showing that the recency effect had in fact been destroyed by the interference task. This also supports my hypothesis that fewer words will be recalled from the last third if an interference task is introduced.

Discussion

Validity

The study we conducted was overall reasonably valid. Validity and reflected well the results that Glazner and Cunitz (1966) got and therefore is had predictive validity. The experiment also had face validity because the results that were got were expected. The study was also valid in that it used a natural experiment design and therefore had high ecological validity. Also it used a matched pairs design, which attempted to cater for any individual differences between different people.

The experiment had good ethics in that the participants had the right to withdraw at any time and their results would be discarded and not counted in the overall study results. The participants also gave informed consent to conduct in the experiment also the participants were debriefed after the experiment was conducted.

The experiment abided by several different controls preventing too many extraneous and confounding variables arising. The experiment also tested what it sought to test.

Improving validity

The experiment was reasonably valid however there were several ways in which the validity could have been improved. The sample size of the experiment was a little small and therefore would limit the validity also the sample was taken from a group of people from the same region and this again limits the validity of the results. Ideally the experiment should have been conducted all around Britain with a much larger sample size of 2000 for example this would then increase the ability of the experiment to generalise. Also changing the interference task would ensure that it is not the particular interference task that we done being the reason people didn’t remember words from the ends of the list. Also it could be argued that the matched pairs design that was chosen was not accurately matched as we based our matching on the scores that the participants got a GCSE level. It may have been better to give the participants a test before they done the experiment to test their ability and therefore giving a more accurate matched pairs design.

Reliability

The experiment went ahead without any glitches and therefore there were no obvious reasons why the results would not have been accurate. Therefore if errors were to arise it would be because of the controls, the following were used.

For each group the same reader read 1 word per second for 30 seconds in order.
Both groups had 40 seconds for free recall

Same list of words was read
Conducted within 5 minutes of each other
Conducted under same weather conditions
Reader read the word list from the same position in the room
Reader attempted to read the word list at the same volume and

But due to the amount of controls and the use of accurate measuring equipment such as a stopwatch this means that error would be minimal as the controls that were used were useful and prevented confounding and extraneous variables

Improving Reliability

However the methodology of selecting the matched pairs sample may mean that the results may not be the same if it was conducted again. The experiment is not very difficult to replicate but the major problems would lie in the reading of the words so ideally it would have been better to create a pre-recorded tape of the words being read out this would prevent errors arising here and would make replicating the study easier.

Implications of study

The results of the study (like Glazner and Cunitz (1966) found as evidence for short term and long term memory) reflected the hypothesis in that it implies that after being told some information and then given a task to interfere with the rehearsal loop than fewer words will be remembered from the end of the list. The reason fewer words were remember from the end of the list was because of the primacy recency effect which suggested that if an interference task is introduced then the recency effect would be destroyed.

Generalisation of findings

Because the study was conducted on a 6th form group of psychology students using an opportunity sample and the sample size was pretty small (22 people) this greatly prevents from generalising from the results of the experiment. Also the fact it was conducted in a very short time in a small area that again means generalisation would not be possible.

Application of findings

In real life this study has a lot of practical uses. A good place in which it could be relevant is in advertising. For example if a company is trying to advertise their product they will want their name to be remembered and therefore all the important information at the beginning and end of the advertisement to ensure that the vital information is remembered and in this way they will improve the effectiveness of advertisement.

Appendix

Word list

Then the reader reads the following words to the participants.

Light

Door

Tree

Frame

Watch

Blazer

Radio

Stone

Trolley

Pigtail

Paper

Water

Loaf

Coach

Potato

Busstop

Trainer

Road

Curtain

Football

Computer

Skylight

Finger

Soap

Boat

Pebble

Fish

Beaker

Tomato

Dustbin

References

Atkinson, R.C and Shiffrin, R.M (1968) Human memory: A proposed system and its control processes. In Spence, K.W. and Spense, J.T. (eds) The Psychology of learning and motivation, Vol.2. London: Acadamic Press

Glazner, M. and Cunitz, A.R. (1966) Two storage mechanisms in free recall. Journal of Verbal Vearning and Verbal Behaviour, 5, 351-60

Murdock, B.B., Jr. (1961). The retention of individual items. Journal of Experimental Psychology, 62, 618-625.