Statistics for Behavioural Science Lab

This study examines the accuracy of eyewitness testimony and the misinformation effect in the context of a Statistics for Behavioural Science Lab. It explores the relationship between stress and recall, as well as the decay of memory over time. The study involves participants watching a video of a bank robbery and answering questions about the details. The results provide insights into the factors that influence memory and recall. The study was conducted with student participants from South University.

Running head: STATISTICS FOR BEHAVIOURAL SCIENCE LAB 1
Statistics for Behavioural Science Lab
By (Name of Student)
(Institutional Affiliation)
(Date of Submission)

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Introduction
Social scientists have long been interested in the accuracy of eyewitness testimony. Several
studies over the past few decades have demonstrated that eyewitnesses are not always
accurate (e.g., Buckhout, 1974; Bornstein & Zickafoose, 1999). More recently, many
individuals have filed appeals based on deoxyribonucleic acid (DNA) evidence. Of those
acquitted on this basis, 78 percent had originally been convicted based on strong eyewitness
testimony (Stambor, 2006). One reason witnesses may err when recalling information about a
criminal is the misinformation effect, which involves "incorporating 'misinformation' into
one's memory of the event after receiving misleading information about it" (Myers, 2008).
Elizabeth Loftus (1978, 1979a, 1979b, 2001) and her associates have repeatedly
demonstrated this effect, finding that memory can be "constructed" based on suggestive
questions and information given after the fact. Other factors that play a role in our ability to
recall information are decay and stress. Shapiro & Penrod (1986) presented evidence that
suggests memory may decay over time, while other researchers have found that as stress
increases, the accuracy of recall decreases (Deffenbacher, Bornstein, Penrod, & McGorty,
2004; Payne, Nadel, Allen, Thomas, & Jacobs, 2002).
Hypothesis
For this study and based on our literature above, different hypotheses for this study can be
given as follows.
H1: There will be a relationship between the type of information conveyed (a
misinformation effect) and the accuracy of recall about the colour of the vehicle.
H2: Memory may decay over time.
H3: The level of stress will affect recall.

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H4: There will be a relationship between the level of stress and confidence, such that
confidence declines as stress rises.
Method
Participants
There were 40 student participants from an introductory psychology project at South University. The
groups were broken down into various groups for analysis and statistic research. These groups
consisted of: age-which ranged from 18 to 54 with a mean age of 29.7, se 1.66, sex-consisting of 20
male candiates and 20 female canidates, height-which ranged from 53 inches to 79 inches with a mean
of 40 and year in college- which was broken down with 5 female canidates and 5 male canidates for
each year, making that 10 canidates for each year. During the statistical research, graphs and tally
charts were provided to further analyze data accordingly.
Procedures
Participants are randomly assigned to one of three levels of stress: high stress, where they are
writing a final exam immediately following their participation in the experiment; medium
stress, where they are writing a final exam the day following their participation; and low
stress, where their participation comes two weeks prior to their final exam. They are shown
one of two different versions of a video of a bank robbery and instructed to pay close
attention to detail.
All versions share the same beginning scenario, with two individuals entering a bank to rob
it. The first individual (individual #1) is 5'10" tall and of medium build, wearing blue jeans, a
black leather jacket, and black tennis shoes. This individual is wearing a ski mask with the
holes around the eyes large enough for the color of the skin, which is white or light colored,
to be visible. The second individual (individual #2) is 6'2" and heavyset, wearing black sweat
pants, a red jacket, and dark work boots. This individual is wearing a ski mask identical to
that of individual #1. The skin around the eyes is dark. No other skin is visible on either

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individual. Individual #1 walks to the window and hands the teller a note, bringing up the
right hand, which is in the pocket, to simulate a gun. It is unknown whether an actual gun was
used. Individual #2 stays back a step as if keeping watch. After the teller gives money to the
robber, the two robbers leave the bank, jump into a car waiting at the curb, and drive away. In
version #1, the car is blue. In version #2, the car is green.
Following the viewing of the video, each participant meets an individual in the waiting room.
This individual (actually a confederate of the experimenter) states that he or she had lost
something and had come back to see whether the experimenter found it. The individual
begins a conversation about the video and says, "Did you see that blue (or green, depending
on the condition) car they were driving?” Half the time, this question is congruent (the color
mentioned by the confederate matches the color shown in the video). And half the time, the
color is incongruent (the color mentioned by the confederate is different from that visible in
the video).
Measures
At the end of this conversation, the confederate leaves, and the participant is asked by the
experimenter to complete a short questionnaire to measure his or her memory of the details in
the video. This questionnaire consists of fifteen fill-in-the blank questions where participants
are asked questions, such as "What kind of pants was the individual who asked for the money
wearing?" The participant must write what he or she recalls or "unknown" if uncertain about
the response. Each correct answer is given one point, and the points are added to create a
continuous measure of recall as the dependent variable. Scores on this measure can range
from 0 to 15. This questionnaire is given again two weeks later, and a third time after one
month.
Participants are also asked to rate their confidence in their recall of each item on a scale of 1
to 10, with one meaning very little confidence and 10 meaning a great deal of confidence.

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These items are added to create an overall confidence score, with higher scores indicating
higher levels of confidence. Scores on this measure can range from 15 to 150.
The misinformation effect is stored in a variable named “recall color.” Recall color is scored
as "Correct" if participants correctly identify the color of the car they had seen in the video
and "Incorrect" if they incorrectly identify the color.
Finally, all participants complete a short questionnaire to measure their stress levels. This is
necessary to check the stress manipulation and ensure it was effective. Possible scores on this
measure range from 0 to 25, with higher scores indicating higher levels of stress.
Results and Discussion
Descriptive Statistics
N Minimum Maximum Mean Std. Deviation
Age 72 18 49 27.75 7.845
StressScore 72 1 25 12.22 7.161
Recall 1 72 0 15 7.53 3.233
Recall 2 72 1 13 6.57 2.803
Recall 3 72 0 13 5.13 2.567
Confidence 72 54 150 100.40 26.272
Valid N (listwise) 72
H1: There will be a relationship between the type of information conveyed (a
misinformation effect) and the accuracy of recall about the color of the vehicle.
Type of Information * Recall Color Crosstabulation

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Count
Recall Color
TotalCorrect Incorrect
Type of Information 1 0 0 1
Consistent 0 27 9 36
Inconsistent 0 15 21 36
Total 1 42 30 73
Chi-Square Tests
Value df
Asymptotic Significance
(2-sided)
Pearson Chi-Square 81.343a 4 .000
Likelihood Ratio 18.981 4 .001
N of Valid Cases 73
a. 5 cells (55.6%) have expected count less than 5. The minimum expected count is .01.
H2: Memory may decay over time.
One-Sample Test
Test Value = 0
t df Sig. (2-tailed) Mean Difference
95% Confidence Interval of the
Difference
Lower Upper

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Age 30.015 71 .000 27.750 25.91 29.59
StressScore 14.483 71 .000 12.222 10.54 13.90
Recall 1 19.760 71 .000 7.528 6.77 8.29
Recall 2 19.890 71 .000 6.569 5.91 7.23
Recall 3 16.940 71 .000 5.125 4.52 5.73
Confidence 32.427 71 .000 100.403 94.23 106.58
H3: The level of stress will affect recall.
Model Summaryb
Model R R Square
Adjusted R
Square
Std. Error of the
Estimate
1 .718a .516 .495 5.090
a. Predictors: (Constant), Recall 3, Recall 1, Recall 2
b. Dependent Variable: StressScore
ANOVAa
Model Sum of Squares df Mean Square F Sig.
1 Regression 1878.394 3 626.131 24.163 .000b
Residual 1762.051 68 25.913
Total 3640.444 71
a. Dependent Variable: StressScore

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b. Predictors: (Constant), Recall 3, Recall 1, Recall 2
Coefficientsa
Model
Unstandardized Coefficients
Standardized
Coefficients
t Sig.
95.0% Confidence Interval for B
B Std. Error Beta Lower Bound Upper Bound
1 (Constant) 23.958 1.668 14.360 .000 20.629 27.287
Recall 1 .515 .535 .233 .962 .339 -.553 1.584
Recall 2 -2.392 .807 -.936 -2.963 .004 -4.002 -.781
Recall 3 .019 .835 .007 .023 .982 -1.648 1.686
a. Dependent Variable: StressScore
H4: There will be a relationship between the level of stress and confidence, such that
confidence declines as stress rises.
Correlations
StressScore Confidence
StressScore Pearson Correlation 1 -.706**
Sig. (2-tailed) .000
N 72 72
Confidence Pearson Correlation -.706** 1
Sig. (2-tailed) .000
N 72 72
**. Correlation is significant at the 0.01 level (2-tailed).
Discussion

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An independent sample t-test is also known as a between-subjects design (Gravetter,
Wallnau, Forzano, 2017, p. 268). An independent-samples t-test was run to test the
hypothesis that there is a relationship between the level of stress and confidence, such that
confidence declines as stress rises. The test was not significant (t(36) = -8.91, p <0.0001).
Males (μ= 70.85, SD = 2.7961) do not differ from stress level (μ = 63.7, SD = 2.2501) in
their confidence.
References
Bornstein, G. HY., & Zickafoose, D. J. (1999). "I know I know it, I know I saw it": The
stability of the confidence-accuracy relationship across domains. Journal of
Experimental Psychology: Applied, 5, 76–88.

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Buckhout, R. (1974). Eyewitness testimony. Scientific American, 23–31.
Deffenbacher, K. A., Bornstein, B. H., Penrod, S. D., & McGorty, E. K. (2004). A meta-
analytic review of the effects of high stress on eyewitness memory. Law and Human
Behavior, 28(6), 697–706.
Gravette, F. J., Wallnau, L. B. (01/2013). Essentials of Statistics for the Behavioral Sciences,
8e, 8th Edition. [Vital-Source Bookshelf Online]. Retrieved
from https://digitalbookshelf.southuniversity.edu/#/books/9781285956565/
Loftus, E. F. (1979a). Eyewitness testimony. Cambridge, MA: Harvard University Press.
Loftus, E. F. (1979b). The malleability of human memory. American Scientist, 67, 312–320.
Loftus, E. F. (2001). Imagining the past. The Psychologist, 14, 584–587.
Loftus, E. F., Miller, D. G., & Burns, H. J. (1978). Semantic integration of verbal information
into a visual memory. Journal of Experimental Social Psychology: Human Learning
and Memory, 4, 19–31.
Myers, D. G. (2008). Social psychology (9th Ed.). New York, NY: McGraw Hill.
Payne, J. D., Nadel, L., Allen, J. J. B., Thomas, K. G. F., & Jacobs, W. J. (2002). The effects
of experimentally induced stress on false recognition. Memory, 10(1), 1–6.
Shapiro, P. N., & Penrod, S. (1986). Meta-analysis of facial identification studies.
Psychological Bulletin, 100, 139–156. Stambor, Z. (2006). How reliable is eyewitness
testimony? APA Monitor, 37(4), 26–27.

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APPENDIX: DATA

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ID Sex Ethnicity Age Car Type of Information StressLevel StressScore Recall1 Recall2 Recall3 Confidence Recall Color
1 F L 23 Blue Consistent Low 3 12 10 7 100 Correct
2 F AA 35 Blue Consistent Low 5 6 5 3 112 Correct
3 F AA 21 Blue Consistent Low 2 11 11 9 125 Incorrect
4 F C 42 Blue Consistent Low 9 3 4 2 150 Correct
5 F C 37 Blue Consistent Low 7 8 8 6 136 Correct
6 F AA 26 Blue Consistent Low 4 13 12 9 107 Correct
7 M O 24 Green Consistent Low 3 10 9 7 143 Incorrect
8 M C 19 Green Consistent Low 1 15 13 13 141 Correct
9 M AA 28 Green Consistent Low 4 11 10 8 134 Correct
10 M C 20 Green Consistent Low 2 12 11 9 148 Correct
11 M C 31 Green Consistent Low 5 9 7 5 139 Incorrect
12 M L 22 Green Consistent Low 3 10 9 7 117 Correct
13 F AA 25 Blue Consistent Medium 7 11 9 8 76 Correct
14 F C 32 Blue Consistent Medium 8 5 5 3 99 Correct
15 F C 27 Blue Consistent Medium 11 10 7 5 124 Incorrect
16 F C 36 Blue Consistent Medium 9 4 6 5 83 Correct
17 F AA 24 Blue Consistent Medium 13 7 5 4 105 Correct
18 F L 29 Blue Consistent Medium 10 12 10 7 78 Correct
19 M AA 18 Green Consistent Medium 15 9 8 6 91 Incorrect
20 M C 19 Green Consistent Medium 12 8 8 5 107 Incorrect
21 M L 21 Green Consistent Medium 10 10 9 7 102 Correct
22 M AA 22 Green Consistent Medium 14 4 5 3 120 Correct
23 M C 39 Green Consistent Medium 17 5 4 2 111 Incorrect
24 M O 33 Green Consistent Medium 16 9 7 6 115 Correct
25 F AA 23 Blue Consistent High 17 9 7 5 94 Correct
26 F L 25 Blue Consistent High 18 3 2 2 58 Correct
27 F AA 32 Blue Consistent High 21 8 6 5 73 Incorrect
28 F C 22 Blue Consistent High 19 2 1 1 67 Correct
29 F AA 45 Blue Consistent High 23 5 3 4 81 Correct
30 F C 49 Blue Consistent High 20 10 7 6 92 Correct
31 M C 36 Green Consistent High 25 7 5 5 55 Correct
32 M L 20 Green Consistent High 22 6 5 4 76 Incorrect
33 M C 19 Green Consistent High 17 8 7 7 60 Correct
34 M C 24 Green Consistent High 24 2 6 4 89 Correct
35 M L 27 Green Consistent High 21 3 4 2 72 Correct
36 M AA 24 Green Consistent High 18 7 4 2 78 Correct
37 F C 23 Blue Inconsistent Low 5 11 10 8 97 Correct
38 F L 35 Blue Inconsistent Low 4 7 7 5 107 Incorrect
39 F AA 21 Blue Inconsistent Low 3 12 10 9 120 Correct
40 F C 42 Blue Inconsistent Low 8 5 5 4 146 Incorrect
41 F O 37 Blue Inconsistent Low 9 9 8 6 132 Incorrect
42 F C 26 Blue Inconsistent Low 3 12 11 9 103 Correct
43 M L 24 Green Inconsistent Low 4 12 10 8 138 Incorrect
44 M AA 19 Green Inconsistent Low 3 8 7 5 136 Correct
45 M C 28 Green Inconsistent Low 2 11 11 9 132 Correct
46 M AA 20 Green Inconsistent Low 6 9 9 7 143 Incorrect
47 M C 31 Green Inconsistent Low 4 10 9 7 134 Incorrect
48 M C 22 Green Inconsistent Low 4 11 10 9 114 Correct
49 F AA 25 Blue Inconsistent Medium 6 10 8 8 75 Incorrect
50 F L 32 Blue Inconsistent Medium 9 4 3 3 96 Incorrect
51 F C 27 Blue Inconsistent Medium 13 9 7 6 121 Correct
52 F AA 36 Blue Inconsistent Medium 8 5 4 4 80 Incorrect
53 F C 24 Blue Inconsistent Medium 12 6 4 3 102 Incorrect
54 F C 29 Blue Inconsistent Medium 11 11 10 8 75 Correct
55 M C 18 Green Inconsistent Medium 14 8 8 7 89 Incorrect
56 M AA 19 Green Inconsistent Medium 13 7 6 4 104 Correct
57 M C 21 Green Inconsistent Medium 16 9 7 6 99 Incorrect
58 M C 22 Green Inconsistent Medium 15 5 5 3 117 Correct
59 M L 39 Green Inconsistent Medium 11 4 4 4 109 Incorrect
60 M AA 33 Green Inconsistent Medium 15 8 6 5 112 Incorrect
61 F C 23 Blue Inconsistent High 18 7 5 4 93 Correct
62 F AA 25 Blue Inconsistent High 16 1 1 0 59 Incorrect
63 F C 32 Blue Inconsistent High 20 7 5 4 71 Correct
64 F L 22 Blue Inconsistent High 21 3 3 2 68 Incorrect
65 F O 45 Blue Inconsistent High 22 6 4 3 79 Correct
66 F AA 49 Blue Inconsistent High 21 8 5 4 94 Incorrect
67 M C 36 Green Inconsistent High 25 5 4 3 54 Incorrect
68 M AA 20 Green Inconsistent High 23 4 4 2 77 Correct
69 M L 19 Green Inconsistent High 19 6 5 3 62 Incorrect
70 M AA 24 Green Inconsistent High 23 0 1 0 87 Incorrect
71 M C 27 Green Inconsistent High 22 5 5 3 70 Correct
72 M L 24 Green Inconsistent High 17 3 3 1 76 Incorrect

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