Impact of Emotion 1
Running head: IMPACT OF EMOTION ON DECLARATIVE
Impact of Emotion on Declarative Memory in Depressed
Versus Non-depressed Individuals
Katie Cardella
St. Bonaventure University
Impact of Emotion 2
Abstract
Kazui et al (2000) observed the impact of emotional stimuli on the declarative recall ability in Alzheimer’s patients. The findings of this study along with other similar studies have shown that emotion helps facilitate declarative memory. Studies have found that depression can inhibit learning and memory. The following study was a 2 (charge of photo- emotional or neutral) x2 (depression level- low or high) design with the purpose of examining the impact of emotion on the declarative recall. This study takes the findings of Kazui’s (2000) study and applies the idea that emotion helps memory and applies it to a different population of subjects. It was predicted that emotional stimuli will yield higher recall results than neutral stimuli. It was also predicted that individuals with low depression would have higher recall accuracy than those with high depression. There was a main effect of emotion such that greater recall accuracy was reported for the emotional photograph as compared to the neutral photograph. This supported the hypothesis that emotional stimuli facilitate declarative memory. There was no main effect of depression nor was there an interaction between the two variables. It is concluded that emotional stimuli facilitates recall ability in individuals independent of the presence of depression based on the design of this study.
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Impact of Emotion on Declarative Memory in Depressed
Versus Non-depressed Individuals
Declarative
memory is the aspect of
memory that stores facts, figures and events. It is based on pairing the
stimulus with a correct response and is closely related to textbook learning.
Declarative memories are best established by using active recall combined with
mnemonic techniques and spaced repetition (http://en.wikipedia.org). There are
however, some other factors that can play into delcarative memory, namely
affect and depression.
Emotion and affect have been shown to have an effect on declarative memory. In a study conducted with Alzheimer's patients, Kazui et al (2000) used short stories to test the memory of their subjects. The stories were either netrually charged or emotionally charged. They hypothesized, and concluded through their data, that emotional arousal enhances declarative memory in patients with Alzheimer's disease. Their ideas for future research included testing this method on other patients, such as those with dementia and other conditions that can be debilitative towards memory. This can also be applied towards individuals with depression, which has been shown to impair memory and other cognitive functions. Bower (1992) also looked at how emotion was involved with learning and memory. In his study, Bower argued that emotion directs attention to causally significant aspects of a discrepant situation, and that arousal of emotion retrieves associated thoughts, plans, and memories. This phenomenon is somewhat similar to, but still differs from mood-state-dependent-memory, which is learning that takes place in one
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situation or "state" is
generally better remembered later in a similar situation or state. For example,
subjects who are sad are better able to remember unhappy or unpleasant memories
and subjects who are happy are better able to remember happy or pleasant
memories (http://www.memorylossonline.com). The present study however is not concerned with the mood of the subjects
at the time of testing, rather, only the emotion experienced by the subjects as
a result of vieiwng the photographs is considered.
Another factor that can play a role in recall
ability is the presence of depression. Previous studies have shown that
depression can have a negative impact of certain cognitive abilities, including
declarative memory. Huegel (1996) found
that depressed
individuals demonstrate more deficits of declarative memory and other
cognitive abilities as compared to non-depressed
individuals. This is
one of many studies showing that clinical depression affects a number of
cognitive functions, in particular, visual and verbal memory and naming, which
is closely realted to declarative memory. Comparisons such as these however are
not limited to clinical depression. Numerous studies, such as those conducted
by Crumrine (2003), Huegel (1996) and Kizilbash et al (2002) looked at individuals
exhibiting some
symptoms of depression, rather than
clinically diagnosed depression and still yielded similar results to those
studies concerned with clinically depressed individuals. This is important
given that the current study is only concerned with individuals exhibiting
symptoms and personality tendencies towards depression rather than those with
clinical depression.
The purpose of the present study is to test the findings of
previous studies, which showed that emotional stimuli, in this case emotional
visual stimuli, help to facilitate
Impact
of Emotion 5
declarative recall ability. Since it is also hypothesized that
depression plays a debilitative role in memory ability, this study also serves
to test the impact of depression levels on recall. It is predicted that there
will be a main effect of depression; Individuals with low depression scores
will have more accurate recall of the photographs than those with high
depression scores. It is also predicted that there will be a main effect of
emotion; the emotionally charged photos will yield higher recall accuracy than
the neutral photos. It is also predicted that there will be an interaction of
the emotional charge of the photos and depression level in that the
emotionality of the pictures is more powerful than depression in determining
recall. The difference in the recall between depressed and non-depressed will
rely on the level of emotion of the photographs.
Method
Subjects
Thirty undergraduate students participated in this study. All participants were over the age of 18 and consisted of 11 males and 19 females. Subjects could not be colorblind and participate in this experiment.
Materials
The Beck Depression Inventory II (BDI-II) was used for depression testing purposes. Two photographs were also used; one of an emotional scene, and one of a neutral scene.
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Procedure
Testing took place over the course of 3 weeks. Participants were tested one at a time. Participants were asked to complete the BDI-II, however they were not told what the test was measuring. After completing the BDI-II, the participants were told they were about to see 2 photographs and that they had 20 seconds to study each photo. The order of picture presentation was rotated for each day of testing. After viewing the first photo, the participants were given a form consisting of 10 questions pertaining to the photo they just saw. These 10 questions asked the participants to recall certain details of the photograph. After completion of the question form, the same procedure was followed for the second photo. Before viewing the emotional photo, the participants were told a brief fictitious caption for the photo which was used to enhance the emotional impact of the photo. The caption described the photo as a funeral scene involving a child whose parents were just killed in a suicide bombing overseas.
Hypothesis
1) There
will be a main effect of depression; more highly depressed individuals will
have a lower recall of picture details than lower depressed individuals.
2) There will be a main effect of the emotional charge of the pictures; Emotionally charged pictures will yield higher recall accuracy than neutral pictures.
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3) There will be an interaction between the variables. The emotionality of the pictures is more powerful than depression in determining recall. The difference in the recall between depressed and non-depressed will rely on the level of arousal such that the effect of depression in individuals on recall will be dependent upon the emotionality of the photo.
Results
Depression index scores ranged from 0
to 15, out of a possible 60, with a mean of 4. . The mean recall for the
emotional photos were 8.5 and 9.0 for the low and high depression categories
respectively. The mean recall for the neutral photos were 7.1 and 7.8 for the
low and high depression categories respectively An analysis of variance was
performed with the specified level of significance set at p = .05. The within
subject ANOVA for emotion yielded the results, F (1,28 ), 13.063 , p< 0.001, showing a main
effect of emotionality on recall. There was no
main effect of depression on recall as a between subject ANOVA yielded the
results; F(1,28) 1.321, p> .05. There was no interaction
between the two variables as an ANOVA yielded the results; F(1,28),
.055, p > .05
Discussion
This data was found to be congruent with that of the previous studies that suggested that affect and emotion help to facilitate declarative memory. As was hypothesized, there was a main effect of emotion as the emotionally charged photo
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yielded a statistically significant higher accuracy report than the neutral photograph. The depression factor was difficult to determine as none of the participants fell into the "high depression" category. Since the purpose of the test was not to measure clinical depression, the level determining “high depression” was lowered to 10 for the purposes of this study. The highest score off the BDI-II was 15 out of 60, indicating a low level of depression. Only 4 of the 30 participants could be categorized in the newly determined “high” depression category. Those participants however, did not have significantly lower recall scores than those in the “low” depression category. In fact, the mean recall of those 4 individuals was higher than that of the non-depressed participants in both photo conditions. The mean recall for depressed individuals for the emotional photo was 9.0 as opposed to 8.5 for the non-depressed individuals. For the neutral photo, depressed individuals had a mean recall score of 7.8 compared to the non-depressed individuals mean score of 7.1. These numbers could be due to the low sample size of depressed subjects and may not reflect the true effect of depression on recall. Further testing needs to be conducted with a higher sample size of depressed individuals in order to make a determination of the effect of emotion on recall in depressed individuals.
While the effect of depression on recall ability could not be clearly determined, the effect of emotion on recall was evident. It was predicted that the emotionality of the
photo outweighed the depression factor, making the lack of variety in depression scores a minor setback.
This procedure originally called for the participants to have 30 seconds to study the photographs. This was shown to be too long of a time period as the photos were not
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that involved or detailed. Once actual testing began, the time allowed to study the photos was shaved to 20 seconds.
The emotional
photo used was a scene from a funeral in
The ANOVAs performed showed that there was a main effect of the emotional charge of the photos. Figure 1 shows that emotion did in fact play a role in recall ability for the details of the photos (declarative memory). The data was statistically significant concerning the effect of emotion on recall, supporting the hypothesis that emotionally charged pictures will yield higher recall accuracy than neutral pictures. It was expected however, that if different levels of depression were present, that that would have an impact on the recall accuracy. There was simply not a high enough depression score to qualify as "high." Therefore, the hypothesis that more highly depressed individuals will have a lower recall of picture details than lower depressed individuals could not be accurately analyzed. This also affected the hypothesis concerning the interaction for the two variables. The data for the interaction was also not significant, again due to the low incidence of high depression scores.
Future research in this area could include different populations of subjects including subjects with varying cognitive, learning, and mood impairments. The present
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study could be improved upon by working with a population more likely to yield both high and low depression scores. While it was shown in this study that emotional stimuli
helps facilitate declarative memory, it is important to look at this in different groups of individuals, particularly individuals with depression or another condition that inhibits memory and learning in order to see emotions true effect.
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References
Bower, G. (1983).
How
might emotions affect learning? The handbook of emotion and memory: Research and theory.
Crumrine, J. (2003). The effects of anxiety and
depression on memory complaints and memory performance in older adults. Dissertation Abstracts
International, 63(12-B), 6089.
Huegel, S.(1996). An examination of the
subcortical hypothesis of depression: Ramifications for memory, naming, and
other cognitive abilities. Dissertation Abstracts International, 57(1-B), 698
Kazui, H., Mori,
E., Hashimoto, M., Hirono, N. Imamura, T., Tanimukai, S., Hanihara, T., et
al.(2000). Impact of emotion on memory; Controlled study of the influence of
emotionally charged material on declarative memory in Alzheimer’s disease. British
Journal of Psychiatry, 177, 343-347.
Kizilbash, A. (2002). The effects of depression and
anxiety on memory performance. Archives of Clinical Neuropsychology, 17(1), 57-67.
Memory Loss & the Brain (2004). State Dependent Memory. Retrieved March 7, 2004 from http://www.memorylossonline.com/glossary/statedependentmemory.html.
Wikipedia: The Free Encyclopedia (2004) Retrieved March 18, 2004, from http://en.wikipedia.org/wiki/Declarative_memory
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12
Table 1: Mean Recall Scores for Emotional and Neutral Photos in Low and High Depressed Groups.
Emotional Neutral
|
9.0 |
7.8 |
|
8.5 |
7.1 |
High
Low
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Table 2: Analysis of Variance for Recall of Emotional and
Neutral photos in Depressed and
non-depressed individuals
Between Subjects (Depression)
|
Source |
SS |
df |
MS |
F |
P |
|
DEPRESSION |
2.385 |
1 |
2.385 |
1.321 |
0.260 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Within
Subject (Emotion)
|
Source |
SS |
df |
MS |
F |
P |
|
Emotion |
12.385 |
1 |
12.385 |
13.063 |
0.001 |
|
|
Interaction
|
Source |
SS |
df |
MS |
F |
P |
|
|
|
|
|
|
|
|
|
|
|
|
Emotion*Depression |
0.052 |
1 |
0.052 |
0.055 |
0.817 |
|
|
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Figure Caption
Figure 1.The mean comparisons of recall accuracy between the emotionally charged and neutral photographs in individuals with high and low depression
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