The Amount of Positive Stimuli as Opposed to Neutral Stimuli Recalled from a Word List

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The amount of positive emotional stimuli recalled as opposed to neutral stimuli from a word list.

Abstract The study of human memory has been a subject of science and philosophy for thousands of years and has become one of the major topics of interest within cognitive psychology. Research in cognitive psychology has shown that there are various factors that influence our memory. One theory in cognitive psychology suggests that emotional events tend to be remembered better than nonemotional events. This experiment was designed with the purpose of ascertaining whether memory is enhanced for positive emotional stimuli as compared to neutral stimuli in UEA undergraduates. The study was a within measures

design whereby the independent variable was the list of positive emotional and neutral stimuli words. The dependent variable was the amount of positive emotional words recalled as compared to neutral words. It was hypothesised that positive emotional stimuli would be better recalled than neutral stimuli. The study used a sample of 100 participants who were all undergraduate students at the University of East Anglia. The hypothesis was supported as the participants recalled more positive emotional words than neutral words.

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The study of human memory has been a subject of science and philosophy for thousands of years and has become one of the major topics of interest within cognitive psychology. Memory refers to the processes that are used to acquire, store, retain and later retrieve information. The hippocampus is a region of the brain that is heavily associated with memory and plays an important role in consolidating information from short-term memory into long-term memory (Cherry, 2011). Renowned brain researcher, Robert M, Sapolsky, has shown that sustained stress can damage the hippocampus as cortisol, a class of steroid hormones, are secreted from the adrenal glands during stress which can prevent the brain from laying down a new memory or accessing already existing memories.

One theory in cognitive psychology suggests that emotional events tend to be remembered better than nonemotional events. A study carried out by Dolcos (2008) investigated this theory by measuring two (ERP) event-related potential effects: the emotion effect (more positive ERPs for pleasant or unpleasant stimuli than for neutral stimuli) and the subsequent memory effect (more positive ERPs for subsequently remembered items than for subsequently forgotten items). ERPs were measured while subjects rated the emotional content of pleasant, unpleasant and neutral pictures. As was expected, subsequent recall was better for pleasant and unpleasant pictures than for neutral pictures. The emotion effect was sensitive to arousal in parietal electrodes and to both arousal and valence in frontocentral electrodes. The subsequent memory effect at centroparietal electrodes was greater for emotional pictures than for neutral pictures. This result suggests that emotional information has privileged access to processing resources, possibly leading to better memory formation.

A study found that glucose administration enhanced fMRI brain activation and connectivity related to episodic memory encoding for neutral and emotional stimuli. Parent et al. (2001) ascertained that glucose enhanced activation related to subsequent successful recall. A double-blind, within-participants, crossover design in which either glucose or a saccharin placebo was administered to healthy young male participants was

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conducted. Emotionally arousing negative pictures and emotionally neutral pictures, intermixed with baseline fixation were shown to the participants while being scanned with fMRI. Free recall was tested at 5 minutes after scanning and again after 1 day. It was found that glucose administration increased activation in regions associated with successful episodic memory encoding. It also enhanced activation in regions whose activity was correlated with subsequent successful recall, including the hippocampus. Finally, glucose substantially increased functional connectivity between the hippocampus and amygdala and a network of regions previously implicated in successful episodic memory encoding.

Doerksen and Shimamura demonstrated that neutral words were less well recalled than emotionally valenced words in their 2001 study. They used two word sets consisting of 32 neutral and 32 emotional words which appeared on a computer screen in a certain colour. Participants completed a mathematical test before the test phase. Participants were tested using the free recall method to see how many words they remembered and which ones. After this, another test was used to see if participants could remember which colour the original word was in or if it was a completely new word. The procedure was repeated several times in more or less the same way but with the words presented slightly differently, the colour had changed for example. They also changed the emotional words in each list to categories, such as vehicles. They found that participants recalled more emotional than neutral words and that salient/categorical words were also recalled more than the neutral words. Research in cognitive psychology has shown that there are various factors that influence our memory. Although the research is vast and thorough, there is not much literature referring to whether memory recall is better for positive or neutral words therefore it is hypothesised that positive emotional stimuli will be better recalled than neutral stimuli.

Method Design This experiment was designed with the purpose of ascertaining whether memory is enhanced for positive emotional stimuli as compared to neutral stimuli in UEA

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undergraduates. The study was a within measures design whereby the independent variable was the list of positive emotional and neutral stimuli words. The dependent variable was the amount of positive emotional words recalled as compared to neutral words.

Participants The study used a sample of 100 participants who were all undergraduate students at the University of East Anglia. A convenience sample was utilized as this technique was fast, easy and the participants were readily available (Hagger-Johnson, Landridge, 2009). 49 male and 51 female participants participated in the memory exercise to see how many words they were able to recall from the list of words comprising of 15 positive emotional words and 15 neutral words (see Appendix 1). The mean age of the

participants was 23.82 years (SD=9.82) with their ages ranging from 18 years to 62 years. All of the participants were approached randomly in and around the University of East Anglia campus and were and opportunity sample. The ethnicity, social class or religion of the participants was not recorded.

Apparatus and Materials A word list containing 15 positive emotional stimuli and 15 neutral stimuli was compiled from a selection of words on the Psychpage website (see Appendix 1). A standardised instruction sheet informing the participants of the key details of the study (see Appendix 2). A participant’s consent form was devised for participants to print their name, provide a signature and date (see Appendix 3). A debriefing sheet was produced in which the study was explained more thoroughly (see Appendix 4). There were one hundred of appendices 1, 2, 3 and 4 produced.

Procedure The experiment was designed by a research group which consisted of five first year undergraduate psychology students from the UEA. The experiment was conducted on the grounds of the UEA where potential participants were approached. The research group created one hundred word lists comprising of 15 positive emotional stimuli and 15

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neutral stimuli and divided them between them, each taking twenty. The researcher introduced themselves to potential participants explaining that they were a psychology student conducting a psychological experiment to test memory recall. The participants were asked if they could spare five minutes of their time to help collect the data that was needed. The participants that were happy to participate were presented with a

standardised instruction sheet and asked to sign a consent form. The researcher then explained that they were to look at the word list for 2 minutes and then write down as many words they could recall on to the answer sheet. After the participants had finished writing down as many words they could remember, they were handed a debriefing sheet in which it explained that the aim of the experiment was to ascertain whether UEA students’ were able to remember more positive emotional stimuli as compared to neutral stimuli from a word list. The participants were informed that any data collected was going to be used solely for the purpose of writing a report. The participants were notified that any of the findings would not be published publicly and anonymity was ensured. The participants were offered no incentive to participate in the study. The option to refrain from taking part in the study and the opportunity to withdraw from the study was also given. Contact email details of the seminar leader were provided to participants in case they required any further information regarding the study.

Results Tests for skewness and kurtosis indicated that the data was not normally distributed (see Table 1). Participant 77 was identified as an outlier and removed. A related t-test was run without the outlier (see Table 2. The mean score for the amount of neutral words recalled (5.31, SD = 2.19) was less than the mean score for the amount of positive words recalled (6.42, SD = 2.07) as shown by a related t-test, t (98) = -4.25, p < 0.05 (one tailed).

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Statistic

Std. Error

________________________________________________________________________ Neutral Skewness Kurtosis 5.4000 .536 .367 .21927 .241 .478

Positive Skewness Kurtosis

6.4600 .251 -.679

.20667 .241 .478

Table 1, Skewness and Kurtosis with outlier in

Statistic

Std. Error

Neutral Skewness Kurtosis

5.3131 .021 -.425

.20338 .243 .481

Positive Skewness Kurtosis

6.4242 .261 -.633

.20562 .243 .481

Table 2, Skewness and Kurtosis with outlier removed

Discussion The hypothesis was supported as the participants recalled more positive emotional words than neutral words, t (98) = -4.25, p < 0.05. The mean amount of neutral words recalled was 5.31 (SD=2.19) was less than the mean score for the amount of positive words recalled 6.42 (SD = 2.07) which is a difference of 1.11. Consequently, the null

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hypothesis was rejected and this provides further evidence to previous findings such as Doerksen et al. (2001) that memory is enhanced for positive emotional stimuli as compared to neutral stimuli. The sample of participants was relatively small with one hundred participants so a bigger sample from the population could have produced results (Coolican, 2003) that were more significant or even not significant at all. The participants that took part in the study were all UEA undergraduate students with assumingly similar cognitive abilities, if the participants were from a more representative sample of the population, the results could have been different. Individual differences could have affected the results too as peoples cognitive ability to recall may be better or worse than others. In the Parent et al. (2001) study, glucose was determined as a factor in helping to enhance fMRI brain activation and connectivity related to episodic memory which may have been a contributing factor in the results that were found in this study. The

participants that took part and done particularly well in recalling more positive emotional stimuli could have had a high sugar or glucose content intake prior to participating in the experiment. There is no way of knowing if this could be a factor as the experiment was not carried out in a laboratory setting where it would have been possible to monitor or record what people had eaten prior to the test. The Dulcos et al. study (2008) also supported the hypothesis as in their study; neutral material was less well recalled. A further study to investigate memory recall for positive and neutral stimuli could include a true experiment conducted in a laboratory setting rather than an experiment conducted in ‘the field’ (Hagger-Johnson, 2009). This could ensure more control with less opportunity for experimental error. There are less ethical concerns with this method also. Although some of the research has provided insights into the recall of positive emotional and neutral stimuli, there are a number of factors that remain to be studied which could include gender differences, age specific differences and maybe how the memory performs at different times in the day.

Word count, 1896, not including title, references, tables/figures and appendices.

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References Coolican, H,. (2003). Aspects of Psychology – Research Methods and Statistics. England :Hodder & Stoughton.

Hagger-Johnson, G, Landridge, D,. (2009). Introduction to Research Methods and Data Analysis in Psychology. Second edition. England : Pearson.

Doerksen, S,. & Shimamura, A. P. (2001). Source memory enhancement for emotional words. Emotion, 1, 5-11.

Dolcos, F, Cabeza, R,. Event-related potentials of emotional memory : encoding pleasant, unpleasant, and neutral pictures. Cognitive Affective Behavioural Neuroscience. 2002, Sep; 2 (3) : 252-63.

Parent, M, B,. Krebs-Kraft, Desiree,L,. Ryan, J,P,. Wilson,. J, S,. Harenski, C,.Hamann, S,.Glucose administration enhances fMRI brain activation and connectivity related to episodic memory encoding for neutral and emotional stimuli. Neuropsychologia. 2001. SciVerse ScienceDirect Journals.

Cherry, K,. 2012. Memory, An Overview of Memory. Retrieved from psychology.about. com/od/cognitivepsychology/a/memory.htm. Accessed on 8th April 2012. www.fi.edu/learn/brain/stress#memory. Accessed on 2nd April 2012. www.psychpage.com. Accessed on 12th March 2012.

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Appendix 1

Air Column

Festive Relaxed

Playful

Optimistic Door Kind

Earth

Farm

Cabinet Loved

Serene Banner

Dynamic

Free Joyous

Machine Fork

Basket

Ink Arm

Tender Passionate

Avenue

Lucky

Lawn Satisfied

Affectionate

Hairdryer

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Appendix 2
Participant instruction sheet: Hi, my name is … I am a psychology student looking for participants, would you be able to spare five minutes of your time to help me collect my data? The aim of this psychological experiment is to simply test memory of a word list. The list will be given to you for 2 minutes, you are expected to memorise as many words from the list as possible. After the 2 minutes the list will be taken away; you are then required to write as many words down that you can remember. If you wouldn’t mind signing this form to give your consent to participate.

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Appendix 3 I, give permission for my results to be used for this experiment on the understanding that I may withdraw from the experiment at any time. I understand that my results will be unidentifiable, stored anonymously and will only be used for this one experimental purpose. Name Signature Date

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Appendix 4 Debrief form Thank you for taking part. The aim of this experiment is to investigate whether UEA students’ are able to remember more positive emotional stimuli compared to neutral stimuli from a list of words. The data we collect will be analysed and used solely for the purpose of writing our reports. The findings will not be published publicly in any way and your anonymity is ensured. Once again, thank you for your participation. If you would like any more information on the experiment, please contact our seminar leader; Simon Hammond – [e-mail]

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Appendix 5 – SPSS Outputs Data with outlier.

Descriptives Neutral Mean 95% Confidence Interval for Mean 5% Trimmed Mean Median Variance Std. Deviation Minimum Maximum Range Interquartile Range Skewness Kurtosis Mean 95% Confidence Interval for Mean 5% Trimmed Mean Median Variance Std. Deviation Minimum Maximum Range Interquartile Range Skewness Kurtosis Statistic 5.4000 4.9649 5.8351 5.3556 5.0000 4.808 2.19273 1.00 14.00 13.00 3.00 .536 1.367 6.4600 6.0499 6.8701 6.4222 6.0000 4.271 2.06667 3.00 12.00 9.00 3.00 .251 -.679 Std. Error .21927

Lower Bound Upper Bound

Positive

.241 .478 .20667

Lower Bound Upper Bound

.241 .478

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Data without outlier.

Descriptives Neutral Mean 95% Confidence Interval for Mean 5% Trimmed Mean Median Variance Std. Deviation Minimum Maximum Range Interquartile Range Skewness Kurtosis Mean 95% Confidence Interval for Mean 5% Trimmed Mean Median Variance Std. Deviation Minimum Maximum Range Interquartile Range Skewness Kurtosis Statistic 5.3131 4.9095 5.7167 5.3148 5.0000 4.095 2.02357 1.00 10.00 9.00 3.00 .021 -.425 6.4242 6.0162 6.8323 6.3822 6.0000 4.186 2.04586 3.00 12.00 9.00 3.00 .261 -.633 Std. Error .20338

Lower Bound Upper Bound

Positive

.243 .481 .20562

Lower Bound Upper Bound

.243 .481

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T-test

Paired Samples Correlations

N Pair 1 Neutral & Positive 99

Correlation .182

Sig. .071

Paired Samples Statistics Mean Pair 1 Neutral Positive 5.3131 6.4242 N 99 99 Std. Deviation 2.02357 2.04586 Std. Error Mean .20338 .20562

Paired Samples Test

Paired Differences 95% Confidence Interval of the Difference Mean Pair 1 Neutral - Positive -1.11111 Std. Deviation 2.60255 Std. Error Mean .26157 Lower -1.63018 Upper -.59204 t -4.248 df 98 Sig. (2-tailed) .000

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References: Coolican, H,. (2003). Aspects of Psychology – Research Methods and Statistics. England :Hodder & Stoughton. Hagger-Johnson, G, Landridge, D,. (2009). Introduction to Research Methods and Data Analysis in Psychology. Second edition. England : Pearson. Doerksen, S,. & Shimamura, A. P. (2001). Source memory enhancement for emotional words. Emotion, 1, 5-11. Dolcos, F, Cabeza, R,. Event-related potentials of emotional memory : encoding pleasant, unpleasant, and neutral pictures. Cognitive Affective Behavioural Neuroscience. 2002, Sep; 2 (3) : 252-63.