Metabolic State Alters Economic Decision Making under Risk in Humans
(Symmonds et al, 2010)
Created by:
Chutikarn Techaboonako (Mild),
Naomi Mwamba, and Samantha Hillock
•
What is it about?
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A study to define whether a change in the state of our metabolism
influences our attitude to risk, specifically in a financial decision.
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This was based on the Prospect Theory.
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Sample:
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19 males who were required to perform a gambling task.
 How?
 They performed this task three times; with a space of a week between
each task.
 On the first occasion, they performed the task after a
fourteen hours fast.
On the second occasion, they did the task immediately after
a 2000 kcal meal,
…and the third occasion, one hour after they had eaten the meal.
Figure 1. Example of the lottery cards used in the risk-preference task.
Results:
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Men with higher baseline levels of leptin (generally more risk averse)
became less risk averse right after eating
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Men with lower baseline levels of leptin (usually less risk averse) had
increased levels of risk aversion.
 …is “when choosing between option yielding gains, humans are
on average risk-averse, while when choosing between options
yielding losses below a reference point, humans make riskier
choices” (Symmonds et al., 2010: 1)
 Problem 1: In addition to what you own, you have been
given $1000
 Alternative (a): A 50 percent chance of gaining $1000
Alternative (b): A sure gain of $500
 Problem 2: In addition to what you own, you have been
given $2000
 Alternative (c): A 50 percent chance of losing $1000
Alternative (d): A sure loss of $500
Source: Adapted from an experiment by Kahnerman and Tversky (1979)
Figure 2: Prospect Theory Graph.
• Loss Aversion!
• With the same value, losses are felt more strongly than gain
 Applications:
 foraging behaviour in animals
 “…sensitivity to risk is systematically influenced by a metabolic
reference point” (Symmonds el at., 2010: 1)
 Experiment Hypothesis:
 “Individuals making monetary decisions would become more
risk-averse after feeding if the meal had a larger impact on
metabolic state (Symmonds et al., 2010)
 “There might also be an immediate shift towards risk-neutrality
due to satiation (a non-humoral, rapid effect), as ecological
models predict a shift towards a risk neutral attitude with
repletion” (ibid)
What did they record?
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•
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Hormone levels, by taking blood samples.
How hungry participants said they were during each metabolic state
(using visual analogue scores).
Percentage of risky decisions and less risky decisions taken by each
participant at each metabolic state.
What did they find?
•
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Significant fall in risk-aversion immediately after eating. However, the
difference between fasting and an hour after eating was not significant.
Participants with higher base levels of leptin took more risks
immediately after eating. By contrast, participants with a lower base
level of leptin took less risks immediately after eating.
Figure 3 Metabolic sate and percentage of higher risk choices.
Source: Symmonds et al. (2010) Metabolic State Alters Economic Decision Making under
Risk in Humans. 5 (6).
Figure 4 Leptin levels and changes in risk aversion.
Source: Symmonds et al. (2010) Metabolic State Alters Economic Decision Making under
Risk in Humans. 5 (6).
Figure 5.1: Metabolic sate and change in risky choice.
Source: Symmonds et al. (2010) Metabolic State Alters Economic Decision Making under
Risk in Humans. 5 (6).
Figure 5.2: Graph of ‘Metabolic sate and change in risky choice’
without the two last samples.
Confirmatory Bias:
 Seeking to confirm the theory
rather than spotting
conflicting information
Over-confidence bias and Optimism:
o Over-estimate knowledge while
under-estimate risk
Gender differences:
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Females are more risk averse in general (Byrnes et al, 1999) as well as in
financial situations (Eckel & Grossman, 2002).
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Therefore, cannot apply findings to females.
Personality and Cultural differences:
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A study across 37 nations – males are generally higher in
Extraversion while females are generally higher in Neuroticism
(Lynn and Martin, 1997 and Feingold, 1994).
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People who are higher in Extraversion are prone to take risks (Soane
and Chmiel, 2005).
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Also, different cultural background  different personality (Lynn
and Martin, 1997)
Emotion
 Sad participants were found to
exhibit greater preference for the
high-risk/high-reward option,
whereas anxious participants
tended to prefer the low-risk/lowreward option. (Raghunathan and
Pham, 1999)
 Sad people spend more on
shopping! (Cryder et al., 2008)
Other Factors:
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Citing many other pieces of
research, Pesti and and Penz state
that factors such as age, occupation,
income and expectations all
influence financial risks, therefore
these findings can only be applied to
25 (±7) year old males.
Our
Sample
Whole
Population
Plus points:
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Did the method three times over a week to minimise order effects.
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Randomised order lottery cards. No participants reported realising
that the same cards were used for each task.
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Didn’t rely on self-reported hunger (though this was recorded). They
measured hormone levels.
Negative Points:
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System bias
• Do men have more risk taking tendencies than women?
If this is the case, then the study appears to suffer from system bias
because only males were used
•
-
The design of the task:
Is it beneficial?
Question of ecological validity
Question of external validity
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Suggested improvements to make it applicable to real financial
situations:
•
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Dragon’s Den
Casino/Poker scenario
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Does this study have implications for businessmen or people in
the financial world?
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When operating in a different zones, manipulating eating
patterns to ensure advantage!
•
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When dealing with someone in a
different time zone, manipulate
their (estimated) eating time if
possible in order to get the best
deal!
Best times to make calculated
financial decisions in terms
of mortgages, investments etc
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Catch the bank manager before his lunch!
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Casinos: to sell food or not to sell food? (or perhaps just snacks)
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Government policy to reduce excessive gambling: all licensed
casinos should sell meals not just snacks
[extreme, control issues etc]
Are there any conflicts of interest?
• There don’t appear to be any conflicts of interest and funding has
been specified.
Is study relevant?
• Yes – expands on research done on non-human animals, though
there appears to be a large jump between animal and human
assumptions. It’s not just a replica for the sake of a replica – new
methodology.
Does the study add anything new?
• Yes, it expands on previous research into financial risk taking
and prospect theory, but uses brand new methodology.
Was the study design appropriate for the research question?
• Yes, to some extent, but the methodology is flawed in terms of
external and ecological validity.
Did the study methods address the most important potential
sources of bias?
• No. The sample causes more potential sources of bias than in
counteracts.
Were the statistical analyses performed correctly and
does the data justify the conclusions?
 Though significant differences were found, they were
small.
 Therefore, we think this is a good paper, which could
influence further studies. However, we also feel that
this paper could be improved through repetition with
a larger data sample.
• Byrnes, J. P., Miller, D. C., Schafer, w. D. (1999). Gender differences in
risk taking: A meta-analysis. Psychological Bulletin, 125(3), 367-383.
• Cryder, C. E., Lerner, J. S., Gross, J. J., & Dahl, R. E. (2008). Misery is
not Miserly: Sad and Self-Focused Individuals Spend More.
Psychological Science, 19 (6), 525-530.
• Eckel, C. C., & Grossman, P. J. (2002). Sex differences and statistical
seterotyping in attitudes towards financial risk. Evolution and Human
Behavior, 23(4), 281-295.
• Feingold A. (1994) Gender Differences in Personality: A Meta-Analysis.
The American Psychological Association, Inc., 116 (3), 429-456
• Ginsburg, H. J., & Miller, S. M. (1982). Sex-differences in chidlrens risk-
taking behavior. Child Development, 53(2), 426-428.Kahnerman, D., &
Tversky, A. (1979). Prospect theory: An analysis of Decision under risk.
Econometrica, 47(2), 263-291
• Lynn, R., & Martin, T. (1997). Gender Differences In Extraversion,
Neuroticism, and Psychoticism in 37 nations. The Journal of Social
Psychology, 137 (30), 369–373.
• Plous, S. (1993) The Psychology of Judgement and Decision making.
United Sates of America: McGraw-Hill, Inc.
o Raghunathan, R., & Pham, M. T. (1999). All Negative
Moods Are Not Equal: Motivational Influences of Anxiety
and Sadness on Decision Making. Organizational Behavior
and Human Decision Processes, 79 (1), 56–77.
o Soane, E., & Chmiel, N. (2005). Are risk preferences consistent?:
The influence of decision domain and personality. Personality
and Individual Differences, 38 (8), 1781-1791.
 Symmonds, M., Emmanuel, J. J., Drew, M. E., Batterham, R. L., &
Dolan, R. J. (2010). Metabolic State Alters Economic Decision
Making under Risk in Humans. PLoS One, 5(6), e11090.
 Young, J. M., & Solomon, M. J. (2009). How to critically appraise an
article. Nature Clinical Practice, 6(2), 82-91.