The document summarizes an experiment that examined the effect of social interactions on self-serving bias. In the experiment, subjects completed tasks in pairs and received feedback on their performance. Subjects then estimated their own contributions. The results showed that subjects who received positive feedback attributed more success to themselves, while those receiving negative feedback blamed external factors. Further analysis found the self-serving bias was influenced by prior interactions between subjects. However, the small sample size prevented determining the exact nature of this relationship. Improving the experiment design with a larger, unbiased sample was recommended for future studies.

1. The effect of social interactions on the self-serving bias
Ilya Bartenev Jethro Elsden Monika Pompeo Gian Luca Tedeschi
University of Nottingham
Experimental Methods in Economics
29 April 2016
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2. Outline
1 What is the self-serving bias?
Definition
Motivation
Measurement
2 Experimental design
Design framework
Methods
3 Results
Summary
Analysis
4 Conclusions
Relevance
Improvements
Summary
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3. Outline
1 What is the self-serving bias?
Definition
Motivation
Measurement
2 Experimental design
Design framework
Methods
3 Results
Summary
Analysis
4 Conclusions
Relevance
Improvements
Summary
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4. What is the self-serving bias?
Murphy’s Law
If more than one person is responsible for a miscalculation, no one will be
at fault.
What is the self-serving bias?
Blaming others or external factors for poor results
Claiming individual credit for success
It is but one of many biases contributing to forming a positive self-image.
Others include:
Overestimating ones ability relative to others
Downward comparison under pressure or threat
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5. Motivation
Implications for economics:
Distorted self-image can lead to difficulties in bargaining and prevent
market clearing (Babcock and Loewenstein, 1997)
Unusually high rejection rates in ultimatum games (Knez and
Camerer, 1995)
Effect on (positive and negative) reciprocity – the reverse is our focus
today
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6. Measurement
How is self-serving bias measured? The most common pattern appears to
be:
Subjects are asked to complete a task as a group
Subjects receive feedback on the overall result
Subjects are asked to estimate their own contribution relative to the
reported result
Studies using this method:
“Among friends. An examination of friendship and self-serving
bias”(Campbell et al, 2000)
“The self-serving bias in a relational context”(Campbell et al, 1998)
Both set a creative task to be completed in a pair people of a varying
degree of closeness and then record perceived own contribution.
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7. Measurement
This is not the only possible way; for example, some other studies deduce
self-serving bias from reactions or descriptions instead of measuring it
directly.
For example, in “Hurting hurts more than helping helps: the role of the
self-serving bias ”(Offerman, 2002) subjects are put into a reciprocity
game situation and their emotional reactions to intentional and random
hurtful or kind moves are noted.
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8. Outline
1 What is the self-serving bias?
Definition
Motivation
Measurement
2 Experimental design
Design framework
Methods
3 Results
Summary
Analysis
4 Conclusions
Relevance
Improvements
Summary
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9. Design framework
Issues to take into consideration in the design:
- Subjects knew each other
- Positive and negative feedback
- Subjects perceive (to some extent) how well they are performing
Limitations:
- Limited time
- Limited number of subjects
- Limited experience of the experimenters
Some of the questions we faced:
- Should we present the subjects with the game payoffs?
- Should we include several rounds?
- How should we incentivize the subjects to report their true beliefs?
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10. Experimental design
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11. Experimental design
Hot response game (Offerman, 2002): The couples start with no
endowment.
The individual payoff is
represented by the sum of
the consequences of both
player’s actions.
The first mover starts by
making his choice, while
the second mover observes
the first mover’s choice
and decide a response be-
tween the given options.
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12. Experimental design
Quiz:
Easy question Hard question
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13. Outline
1 What is the self-serving bias?
Definition
Motivation
Measurement
2 Experimental design
Design framework
Methods
3 Results
Summary
Analysis
4 Conclusions
Relevance
Improvements
Summary
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14. Summary
Score distribution
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15. Summary
Summary of feedback results
Treatment
Difficulty 1 2
Difficult
Mean 3.5 3
SD (1.29) (0.81)
Easy
Mean 5.75 5.75
SD (2.36) (2.21)
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16. Summary
Summary of attribution results
Treatment
Difficulty 1 2
Difficult
Mean 6.25 5.5
SD (1.26) (3.51)
Easy
Mean 5.5 3.75
SD (3.51) (1.26)
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17. Analysis
Attribution distribution by feedback
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18. Analysis
Two-sample Wilcoxon rank-sum tests
Test feedback difference by difficulty: Significant difference at 5%
(p=0.0141);
Test attribution difference by treatment: Significant difference at 10%
(p=0.0722) if feedback 5, no significant difference (p=0.9150) if
feedback <5;
Test attribution difference by type of relation: No significant
difference between kind and unkind behaviour for both feedback 5
(p=0.3173) and feedback <5 (p=0.6547);
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19. Analysis
Difference-in-differences estimation of treatment effect on attribution
Variable Coefficient (Std. Err.)
Feedback -0.090 (0.456)
Treatment -1.847 (3.177)
Treatment#Feedback 0.675 (0.645)
Intercept 5.020∗∗ (2.194)
* p < 0.10, ** p < 0.05, *** p < 0.01
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20. Analysis
Difference-in-differences estimation of interaction effect on attribution
Variable Coefficient (Std. Err.)
Feedback 0.500 (1.068)
Kind -6.800 (7.630)
Unkind 2.250 (9.904)
Kind#Feedback 0.700 (1.368)
Unkind#Feedback -1.000 (2.388)
Intercept 5.000 (4.776)
* p < 0.10, ** p < 0.05, *** p < 0.01
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21. Outline
1 What is the self-serving bias?
Definition
Motivation
Measurement
2 Experimental design
Design framework
Methods
3 Results
Summary
Analysis
4 Conclusions
Relevance
Improvements
Summary
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22. Conclusions
Hypothetical links between SSB and reciprocity:
Offerman (2002): SSB → Reciprocity
Our study: SSB ← Reciprocity
Both directions may be correct.
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23. Conclusions
Possible improvements:
More subjects, and unbiased sample (e.g. strangers rather than
classmates)
Better separation of subjects to prevent communication.
Give subjects a copy of general instructions.
Multiple games/rounds, but need to consider learning by doing.
Investigate different forms of self-serving bias, i.e. blaming external
causes rather than internal causes, division of pie with partner
inflating own share.
Reciprocity by real task instead of computerized one.
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24. Conclusions
Summary:
Prior interaction seems to influence reported contributions.
But small sample prevents us from establishing the nature of the
relationship.
Similar picture emerges when we focus on kind/unkind interaction.
The effects are not significant.
Bigger sample is needed.
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25. THANK YOU
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