Abstract
The question of memory has been an interesting one in psychology for some time. Brown-Peterson hypothesized that distraction tasks have a role to play in how well our memory works, and that this can be measured by a simple task. This research uses a modified version of their experiment to assess their hypothesis. The task involves memorizing a three letter trigram and then taking part in a backwards counting task that was designed as a distractor. 112 participants took part in this experiment. They were asked to complete twenty control trials in which they had to continue counting backwards from a three digit number, and twenty in which they were asked to remember the trigram. A distraction task was presented for between 3 and 15 seconds. The results showed that the length of the distraction task has a significant effect on the recall of the participants. The limitations of this project were the small sample size and the lack of variation in the task. Further research could investigate a comparison between different distractor tasks and the effects that they have on the recall of the participants.
Memory is a challenging and interesting topic in psychology. Understanding the way that memory works is central to understanding how we think and remember things in everyday life. The challenge for psychologists is creating tasks that can be used to measure the different kinds of memory, and making sure that these have reliability and validity. There are a number of different types of memory, but working memory is the one that is used to remember information whilst in the middle of a task. The Brown-Peterson task is designed to understand the limits of working memory and how it is affected by distraction tasks. The original study was designed to test the quantity of objects that can be held in the working memory of the participant in order to understand the capacity of this element of memory (Craik et al., 2007). It is seminal in psychology because it used a distractor task that mimics the use of working memory in real-life scenarios.
Understanding working memory has implications in a number of different areas of psychology. It is perhaps most useful in understanding the differences that occur through the stages of Alzheimer’s disease (Huntley & Howard, 2010). A test similar to those conducted by Brown and Peterson is used for the diagnosis of Alzheimer’s disease and to give insight into the stage that the patient is at. Belleville et al. (2007) also suggest that studies focusing on Alzheimer’s give us insight into the use of working memory in healthy individuals. This research also suggests that there is a difference between the control of attention between Alzheimer’s patients and healthy individual, which again gives significant insight into how memory and attention works in the entire population. This study builds on this research to highlight how these tests can be used to give insight into working memory as a concept.
Cowan (2008) notes that there are significant differences in the processes used within the brain for long-term, short-term, and working memory. Studies such as those conducted by Brown and Peterson allow researchers to discern the difference between these types of memory and how they are used and affected by the environment. Again, the purpose of this study is to assess how the working memory of the participants is affected by distractions. Hasselmo & Stern (2006) note that understanding how this works can give insight into the mechanisms that underlie the use of working memory for the storage of novel information whilst a task is underway. Again, this is useful for understanding the psychology of memory of a wide variety of different people and can be used as part of medical and psychological testing.
Based on the studies conducted by Brown and Peterson, the current research investigates a similar working memory task to highlight the importance of the length of distraction on how well information is stored. Based on this previous research, the hypothesis is that the longer the distraction task, the worse the recall for information will be. It is hoped that the study will give insight into working memory and add to the body of research on the topic.
Method
The aim of the Brown-Peterson task is to prevent the participants from rehearsing their answer. The task involves counting down backwards incrementally (by either 3 or 4) from a 3 digit number. There was a distraction task between each stage that lasted between 3 and 15 seconds. The hypothesis is that the length of the distractor task has an impact on the ability of the participant to correctly recall the pattern of numbers. The method involves taking the memory task 20 times and completing the distractor task in 20 control tasks. This section gives an overview of the methods that were used as part of this research.
Participants
The sample was 112 participants that were all college students. There was an equal number of males and females that participated in the task. The participants were all informed about the nature of the study before taking part, and all gave consent. A debrief was also issued to the participants after they took the task to prevent any negative issues. The participants were varied in age and other factors in order to prevent bias associated with one or more factors.
Materials
The materials used for this project focused on the computer or tablet used to complete the experiment. The individuals were told to take the test in a comfortable location and ensure that they were focused on the task. The computer program that showed the Brown-Peterson task was then set up and the instructions displayed.
Procedure
The participants were asked to complete 40 trials of the task. After the program was set up, the participants pressed start on the program and told how to complete the task. A consonant trigram was displayed in the middle of the screen for one second, and the participants were asked to remember it. The distraction task then appeared on the screen. The distraction task was also in the form of a trigram. This trigram was a three digit number, and the participants were asked to count backwards in multiples of three from this number, with the program giving the first answer as a prompt.
The computer also alternated green and blue circles. The participant was asked to count backwards by three each time of one of these circles appears. At the end of this, the participant was asked one of two questions. If the participant was asked to remember the trigram, then they were to repeat the one that they memorized before the distraction task. If the participant was told to enter the final number, then they had to answer with the next number in the sequence. The participants were told whether they were correct or not. 20 of the trials involved recalling the trigram, whilst 20 involved entering the next number in the sequence.
Results
The total sample size was 112 participants.
A repeated measures (within subjects) one-way ANOVA was performed, with the distractor duration in seconds (3, 6, 9, 12, 15) as the independent variable and the proportion of correct recall as the dependent variable.
The one-way ANOVA revealed a significant effect of condition on reaction time, F(4, 448) = 28.73, p < .001. Therefore, it appears that distractor duration does significantly affect proportion of correct recall.
Post hoc tests using Bonferroni corrections showed that there was a significant difference between the 3-second duration and the 6-second duration (p < .001), the 3-second duration and the 9-second duration (p < .001), the 3-second duration and the 12-second duration (p < .001), and the 3-second duration and the 15-second duration (p < .001). Further there were significant differences between the 6-second duration and the 9-second duration (p = .012), and the 6-second duration and the 15-second duration (p < .001). No other differences were significant.
Note: The average proportion of correct recall in the 3 second distractor duration condition was 0.70, with a standard deviation of 0.27.
The average proportion of correct recall in the 6 second distractor duration condition was 0.54, with a standard deviation of 0.32.
The average proportion of correct recall in the 9 second distractor duration condition was 0.44, with a standard deviation of 0.29.
The average proportion of correct recall in the 12 second distractor duration condition was 0.46, with a standard deviation of 0.31.
The average proportion of correct recall in the 15 second distractor duration condition was 0.41, with a standard deviation of 0.29.
Discussion
Overall, the results of this study show that there is a significant impact of the length of the distractor task on the working memory recall of the individual. As the length of the distraction increased, the average proportion of correct recall decreased, supporting the previous research by Peterson and Brown as well as the researched highlighted in the introduction. The biggest differences were found between the 3 and 6 second conditions, which suggests that the first few seconds are imperative in working memory and instant recall, whilst after a certain amount of time the length of the distraction becomes less important as a factor (Sebastian et al. 2006). This has interesting implications for understanding how working memory works and the length of time that it is used during a memory task. The understanding that working memory is fairly short-term is supported by previous research (Brown et al., 2007).
Limitations
There are a number of limitations in this project which should be noted. The first is that the sample size was fairly limited, and little demographic information was collected. This means that the results may not be generalizable to the whole population and that the effects of this test on working memory might not be applicable to our understanding of memory as a whole. The fact that little demographic information was collected also prevents the use of controlling for variables such as culture, which can have a significant effect on the way that memory works and the effects of the distractor task (Sebastian et al.,2006). Despite this, all participants lived in the United States and were from roughly similar groups in terms of education, which mediates this issue to a certain extent and should not be ignored when assessing the results of the study.
Another limitation is that the task is limited. This means that, if there are any issues with validity and reliability from this particular test, the results might not be measuring working memory capacity but some other cognitive process. It also means that if an individual has difficulty with the distractor task – due to dyscalculia or similar issue – it may have an impact on the results that is not mediated by using a variety of different distractor tasks. If an individual has trouble memorizing letters, this might also have an impact on the results and what they show, as working memory performance might have been more homogenous if the individuals had been allowed to choose the type of information that they were asked to recall. Despite this, the test has been assessed and used in a variety of different research, which suggests that it is overall one of the best measures of working memory capacity.
Future Research
There is the potential that future research can give insight into the issue further. One option would be to carry out the test using a variety of different distractor tasks to help mediate the fact that some individuals might have found the task more challenging and thus struggle with the memory task more. It might also be interesting to conduct two different tests of working memory to assess whether the individuals were showing similar results between the two tests to assess whether the task is valid, or being affected by sociocultural factors. Future research could also compare the results of this group with those obtained from a different group to assess whether there are differences in working memory performance between groups and how the distractor task affected each group.
References
Belleville, S., Chertkow, H., & Gauthier, S. (2007). Working memory and control of attention in persons with Alzheimer’s disease and mild cognitive impairment. Neuropsychology, 21(4), 458.
Brown, G. D., Neath, I., & Chater, N. (2007). A temporal ratio model of memory. Psychological Review, 114(3), 539.
Cowan, N. (2008). What are the differences between long-term, short-term, and working memory? Progress in Brain Research, 169, 323–338.
Craik, F. I., Winocur, G., Palmer, H., Binns, M. A., Edwards, M., Bridges, K., Stuss, D. T. (2007). Cognitive rehabilitation in the elderly: effects on memory. Journal of the International Neuropsychological Society, 13(1), 132–142.
Hasselmo, M. E., & Stern, C. E. (2006). Mechanisms underlying working memory for novel information. Trends in Cognitive Sciences, 10(11), 487–493.
Huntley, J. D., & Howard, R. J. (2010). Working memory in early Alzheimer’s disease: a neuropsychological review. International Journal of Geriatric Psychiatry, 25(2), 121–132.
Sebastian, M. V., Menor, J., & Elosua, M. R. (2006). Attentional dysfunction of the central executive in AD: Evidence from dual task and perseveration errors. Cortex, 42(7), 1015–1020.
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