23 May 2017

Nudge theory and health risk
control measures after theFukushima disaster
Michio Murakami
Fukushima Medical University1

Nudge and a “better” choice “Nudge”
By carefully conveying messages or designing adefault setting, one is able to “nudge” others without
forcing them to make certain better choices.
Nudge theory has its knowledge base in behavioral
science. The main idea behind is that there are noneutral designs in the world.
 In the beginning episode one winter weekend
Consumers have complete freedom of what topurchase, while the display influences their behavior.
So…what is a better choice?
Thaler R.H., Sunstein C.R. Nudge: Improving decisions about health, wealth, and happiness: Yale University Press, 2008
Murakami and Tsubokura (2017) Asia Pac J Public He.

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Nudge and policies
In US, nudge theory attracts attention in the form oflibertarian paternalism, which goes beyond any
partnership of Democratic or Republican. This is usedin economic policies and public health policies.
Incarcerated parents
Nudge: Reference peers
Message: “Other parents have had courts lower their child support
by $200 to $500 per month.”
Result: +11% in applications
Families in need of welfare
Nudge: Emphasize losses
Message: “By not attending your appointment, you may: LOSE up
to $2508 a year in cash benefits.”
Result: +3.6% in attendance
3Bohannon (2016) Science 352(6289), 1042.

Today’s topics
I overview examples of nudges after the Fukushimadisaster.
(1) Risk communication with individuals or multiple
people(2) Default design of risk control measure systems
Examples: whole body counter (WBC) test

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Murakami and Tsubokura (2017) Asia Pac J Public He.

How conveying risk nudges individuals Survival rate 90% vs Mortality rate 10%

 No effect 99.9% vs Cancer risk 0.1%
 Media coverage
WBC test:
94% was not detected vs 6% was detected

Radiation risk on diet:
Lower than natural radionuclides vs Higher thanbenzene

5How providers should convey risk
 Providers’ choices of how to convey risk cannudge people to encourage or to increase anxiety.
 Anxiety could be useful in dealing with risk but
lead to other major risk (risk trade-off) and mentalstresses.
 Providers may try to be neutral, but should
understand how to convey risk can nudge people.
 Misuse of nudge (e.g. increase of risk by nudging)is not justified.
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How a system's default design nudges public Organ donor and mark a section on driver’s licenses
When they are willing to be vs Do not wish to be12% (Germany) vs 99% (Austria)

 Federal program in US, Medicare Part D
Selection following usage history vs Random selection
 700 dollars/year differences WBC testApplicants can participate vs applicants can reject Participation ratio 15% vs 98%

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Examples: WBC tests
 WBC test works to identify high-risk subjects as ascreening. Detection ratio: 0.8% in 2013-2015.
 Some needs WBC to confirm dose levels. Parents
expect an educational effect about radiation onchildren.

 Others immediately stopped eating their favoritefoods.
 Participation ratio: 98% of children and 15% ofadults.
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Examples: WBC tests
Benefits
Identification of high risk
residents

Harms and disadvantages
Possible change oflifestyles

Opportunities for risk
communication andeducation

Costs Children are expected by default to be assessed(involuntary), while for adults, those who wish can be tested(voluntary).
 Voluntary participation has selection biases due to risk
perception and accessibility. An epidemiological approachbased on the presence of biases has been implemented toproject the whole population.
9Nomura et al. (2017) Inter. J. Environ. Res. Public He.

Preferable default settings in systems
 Default setting should be designed according to
the balance between public benefits andharms/disadvantages.
 When public benefit outweighs harm, participation
should be set as the default, allowing applicants
to reject being involved.

 Residents have rights and complete freedom tohave medical services after a disaster in an either
system.
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How authorities design a system’s default
 Authorities’ choices of how to set default insystems can nudge people to participate or not toparticipate.
 In case that participation in inspections related torisks has both benefit and harms, authorities’
default setting is a key factor for overall publicbenefit and harms.
 Authorities should consider possible impacts aswell as fairness, and carefully design the defaultof system.
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Take-home messages
 Providers should understand how to convey risk
can nudge people. Misuse of nudge (e.g. increaseof risk by nudging) is not justified.
 Authorities should carefully design the default ofsystem. Default setting should be designed
according to the balance between public benefits
and harms.

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