V I EW PO I N T A R T I C L E
Conflicting health information: a critical research
need
Delesha M. Carpenter PhD, MSPH,* Lorie L. Geryk PhD, MPH,** Annie T. Chen MSIS,†
Rebekah H. Nagler PhD,‡ Nathan F. Dieckmann PhD§ and Paul K. J. Han MD, MA, MPH¶
*Assistant Professor, **Postdoctoral Research Associate, Department of Pharmaceutical Outcomes and Policy, University of
North Carolina at Chapel Hill, Asheville, NC, †Assistant Professor, Department of Biomedical and Health Informatics, University of
Washington, Seattle, WA, ‡Assistant Professor, School of Journalism & Mass Communication, University of Minnesota, Min-
neapolis, MN, §Assistant Professor, Decision Research, Oregon Health & Science, University Portland, OR, ¶Director, Center for
Outcomes Research and Evaluation, Maine Medical Center, Portland, ME and Tufts University Clinical and Translational Sciences
Institute, Boston, MA, USA
Correspondence
Delesha M. Carpenter, PhD, MSPH
One University Heights
CPO 2125, Asheville, NC 28804
USA
E-mail: dmcarpenter@unc.edu
Accepted for publication
22 November 2015
Keywords: conflicting information,
decision-making, health
Abstract
Conflicting health information is increasing in amount and visibility,
as evidenced most recently by the controversy surrounding the risks
and benefits of childhood vaccinations. The mechanisms through
which conflicting information affects individuals are poorly under-
stood; thus, we are unprepared to help people process conflicting
information when making important health decisions. In this view-
point article, we describe this problem, summarize insights from the
existing literature on the prevalence and effects of conflicting health
information, and identify important knowledge gaps. We propose a
working definition of conflicting health information and describe a
conceptual typology to guide future research in this area. The typol-
ogy classifies conflicting information according to four fundamental
dimensions: the substantive issue under conflict, the number of con-
flicting sources (multiplicity), the degree of evidence heterogeneity
and the degree of temporal inconsistency.
Conflicting health information is a growing
problem worldwide, as evidenced by high-
profile controversies surrounding childhood
vaccination and numerous other health issues.
Mass media have increased the visibility of
such conflicting and often politically charged
controversial health information,1 while a
growing professional emphasis on involving
individuals in health-care decisions has
increased the exposure of patients and provi-
ders to conflicting health information in
clinical encounters.2 More than ever before,
patients, providers, caregivers and policy mak-
ers are expected to evaluate conflicting health
information from different sources, judge
whether the information is credible and decide
how to respond.
Helping people process and evaluate conflict-
ing health information is an increasingly
important need in health care, yet for several
reasons, this need remains largely unmet. Studies
of the prevalence, causes and effects of conflict-
ing health information have been limited.
Although behavioural research outside of the
health-care domain has yielded insights on how
individuals process and evaluate conflicting
information, these insights have not been trans-
lated to health care. Thus, evidence-based
1173ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd., 19, pp.1173–1182
This is an open access article under the terms of the Creative Commons Attribution License,
which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
doi: 10.1111/hex.12438
strategies to help patients make sense of conflict-
ing health information are lacking. The purpose
of this viewpoint article was to highlight what is
currently known about the prevalence, causes
and effects of conflicting health information and
to outline an organized approach for future
research aimed at addressing current knowl-
edge gaps.
Conflicting health information: prevalence,
causes and effects
Evidence on the prevalence of conflicting health
information is limited to the findings of a small
number of studies that examine the perceptions
of patients, physicians and the general public
regarding health topics such as medications, can-
cer screening and nutrition. Studies suggest that
18–80% of patients receive conflicting medica-
tion information,3–7 while approximately 50–
75% of patients8–10 and providers11 perceive
conflicting information about cancer-screening
guidelines. Additionally, 72% of US adults
report medium to high exposure to conflicting
nutrition information.12
Evidence on the causes or sources of conflict-
ing health information is also limited, although
studies have begun to shed light on these issues.
People may encounter conflicting information
actively, while searching for health informa-
tion,13 or passively, as recipients of unsolicited
health advice.14 Conflicting health information
may originate from professional and lay
sources including the Internet, written materi-
als15 and personal testimonials.4 One study that
examined 15 different information sources
found that physicians, media and the Internet
were the most common patient-reported
sources of conflicting medication information.4
The Internet16–18 and media12,19,20 in particular
present a plethora of conflicting information on
numerous health topics,16,17 from screening
guidelines to vaccinations. Social media is an
increasingly common forum for dialogue about
health issues, and studying exposure to conflict-
ing health information on social media and
in other informal settings is increasingly
important given the growing number of indi-
viduals obtaining heath information through
such channels.19
Conflicting health information also has sev-
eral potential negative effects, perhaps the most
important of which is confusion among patients
and providers. When people encounter conflict-
ing health information, they may have trouble
deciding whom to trust and may defer to the
source they deem most credible.20 Although con-
flicting expert opinions about complex issues
such as health-care problems are arguably natu-
ral and expected, laypersons may perceive such
conflict as evidence of intentional bias or expert
incompetence.21 These beliefs, in turn, have been
associated with lower intentions to engage in
health behaviours for which there is clear
scientific consensus (e.g. fruit/vegetable con-
sumption).12 Empirical evidence suggests that
conflicting information may also increase anxi-
ety,22 heighten risk perceptions,23 decrease the
ability of individuals to assess the reliability of
information sources24 and reduce medica-
tion adherence.3,4
When people encounter conflicting health
information, they may also try to make sense of
it using various strategies, including filtering
out misinformation,25 seeking additional infor-
mation from a health-care provider14 and
developing more sophisticated strategies to
appraise it.26 Because greater cognitive effort is
required to process contradictory vs. congruent
information, conflicting health information may
increase individuals’ use of heuristics – or mental
shortcuts – that may exacerbate cognitive biases
or lead to errors in judgment.27 For example,
they may only focus on one source of informa-
tion, such as their doctor,28 and leave out other
important elements,29 or attend to and use infor-
mation that is easier to evaluate.30,31 In
addition, the heightened uncertainty that arises
from conflicting information may motivate peo-
ple to choose information sources and
interpretations that are most consistent with
what they want to believe.32,33 Experimental
work by Brewer and colleagues found that
discordant genetic and standard test results for
risk of recurrence of breast cancer did not
significantly change women’s preferences for
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al.1174
chemotherapy.34 Conflicting information may
also result in decision paralysis – leading people
to simply do nothing at all (a response known as
the status quo bias).35
Conflicting health information: a working
definition
Past research suggests that conflicting health
information is common, increasing in volume
and visibility, and deleterious in its psychologi-
cal and behavioural effects; however, the existing
evidence base on this problem is limited. The
critical need moving forward is to address
knowledge gaps on the prevalence, causes and
effects of conflicting information, but a prerequi-
site for such research is conceptual clarity on
how conflicting health information should
be defined.
We propose defining conflicting health infor-
mation in terms of health-related propositions.
By ‘propositions’ we mean statements or asser-
tions about a health-related issue. These
propositions, furthermore, may pertain to
health-related scientific evidence, interpretations
of the evidence or recommendations and guideli-
nes issued by experts or other individuals.
Propositions may originate from either a single
source or multiple information sources and may
either be actively sought by an individual (e.g.
through an Internet search to determine whether
coffee is bad for your heart) or passively encoun-
tered (e.g. through an overheard conversation
about how coffee causes heart disease).
‘Conflicting health information’ can then be
operationally defined as two or more health-
related propositions that are logically inconsis-
tent with one another. The Merriam-Webster
dictionary defines the term ‘conflicting’ as ‘being
in conflict, collision, or opposition’ or ‘incom-
patible’.36 The defining feature of ‘conflicting’ in
our definition is that the propositions are
discrepant such that a person could not simulta-
neously engage in or believe both propositions
at once. For example, if two propositions dif-
fered on one point, such as the recommended
age to initiate mammography screening (age 40
or 50), a woman could not initiate screening at
both age 40 or 50. Similarly, if a person found a
proposition online that ‘coffee is bad for your
heart’ and the person’s physician told him/her
that ‘coffee is not bad for your heart’, the per-
son could not simultaneously believe
both propositions.
Conflicting health information: a
provisional conceptual typology
Beyond defining the meaning of the phe-
nomenon, conflicting health information can be
classified according to four fundamental dimen-
sions: the substantive issue under conflict, the
number of conflicting sources (multiplicity), the
degree of evidence heterogeneity and the degree
of temporal inconsistency. In Table 1, we pre-
sent text excerpts of conflicting propositions
related to measles–mumps–rubella (MMR) vac-
cinations to illustrate these four dimensions.
The first dimension of conflicting health infor-
mation is the issue of conflict or specific health
topic for which conflicting information exists.
Issue of conflict is important because people’s
reactions to conflicting information may vary
based on the topic. For example, people may
have more negative reactions to conflicting
information regarding vaccine risk than the
schedule for receiving vaccinations. The second
dimension is multiplicity, or the number of dif-
ferent sources of conflicting information. This
dimension is potentially important because the
sheer number of sources of conflicting informa-
tion may moderate its effects. For example,
people may react differently if they encounter
conflicting information about vaccines from a
single source vs. multiple sources, and people’s
negative reactions may increase or plateau as the
number of conflicting sources increases. Evidence
heterogeneity, the third dimension, is important
because individuals may process conflicting
information differently when it comes from
homogenous sources, such as scientific studies,
vs. heterogeneous sources, such as scientific
studies and personal anecdotes. Using the vac-
cine example, a clinician may react differently to
conflicting vaccine safety information from two
scientific journals than to conflicting informa-
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al. 1175
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ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al.1176
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ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al. 1177
tion from a scientific journal and a patient testi-
monial. Temporal inconsistency, the temporal
relationship between conflicting propositions, is
the final dimension. Conflicting information that
is asynchronous (reflecting inconsistency
between logical propositions separated by time)
may produce different behavioural effects than
conflicting information that is synchronous
(reflecting inconsistency between logical proposi-
tions that exist simultaneously). Importantly,
this problem is common and inherent to the nor-
mal advancement of scientific knowledge – a
process in which lower quality evidence (e.g.
from observational studies) is often supplanted
by higher quality evidence [e.g. from randomized
controlled trials (RCTs)]. An additional
consideration for asynchronous conflicting
information is the frequency with which conflicts
arise; if there is less time between exposures to
conflicting propositions, this may have a more
negative impact on individuals than if there is a
greater period of time between exposures to con-
flicting propositions. For example, if MMR
guidelines change yearly, this may more nega-
tively impact trust in sources than if the
guidelines change every 5 years.
Our proposed conceptual typology focuses on
properties of conflicting information itself;
according to our definition, health-related
propositions are either conflicting or not. How-
ever, we recognize that perceptions of conflicting
information, rather than the objective existence
of conflicting information, are important deter-
minants of people’s behavioural responses.
These perceptions, in turn, are determined by
numerous factors including the complexity of
information. For example, individuals may
easily recognize conflicting health propositions
that directly oppose each other: ‘coffee is good
for your heart’ and ‘coffee is bad for your heart’.
In contrast, individuals may find it difficult to
identify conflict in the propositions ‘coffee is bad
for your heart’ and ‘coffee is bad for your heart
if you drink more than one cup per day’. Addi-
tionally, the personal salience of information
may influence the degree to which individuals
perceive informational conflict. Using the coffee
example, someone who does not drink coffee
may be less likely to recognize conflicting propo-
sitions about coffee.
Several other factors may cause individuals to
perceive informational conflict when it does not
exist. For example, a person may perceive
the absence of information as conflicting
information if he/she experiences a rare medica-
tion side-effect of which he/she was never
informed. Individuals may also perceive infor-
mational conflict when confronted by logically
consistent propositions that have different health
implications. For example, a person exposed to
the propositions ‘coffee is bad for your heart’
and ‘coffee prevents Type II diabetes’ may per-
ceive a conflict about whether to drink coffee,
given that coffee drinking has both positive and
negative health outcomes. However, such con-
flict is decisional rather than informational,
because the propositions themselves are not logi-
cally inconsistent. Our operational definition
focuses on informational conflict resulting from
logical inconsistency in alternative health propo-
sitions, rather than decisional conflict resulting
from competing pros and cons of alternative
choice options. Therefore, although the coffee
and diabetes example presented above would
not constitute an instance of informational con-
flict, the causes and mechanisms underlying
individuals’ subjective perceptions of conflict
and how subjective perceptions affect health
decisions are important areas for future
research. Apparent conflicts in information may
also result from differences in the particular out-
comes that are reported in the coverage of
research studies. For example, one news story
may focus on a surrogate outcome, such as pre-
vention of heart attacks, and report a significant
benefit of a drug, while other reports may focus
on cardiovascular disease mortality and report
no benefit. Although these reporting differences
may reflect expert disagreements over which out-
comes ought to be publicized, they do not reflect
true conflicts in the information per se. Finally,
the nature of the decision at hand as well as the
background of the individual making the deci-
sion may determine the extent to which a person
perceives informational conflict. For example, a
patient who must make a decision for which
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al.1178
conflicting information exists – for example to
undergo prostate cancer screening with the
prostate-specific antigen test – may perceive
informational conflict in scientific knowledge,
while a researcher (whose goal is to simply pro-
duce and evaluate the existing knowledge) may
simply perceive available scientific evidence as
being of limited quantity and/or heterogeneous
quality, and not necessarily ‘conflicting’.
At times, informational conflict may also
reflect the varying strength of scientific evidence
and thus may be more perceived than real.
Observational and experimental studies may
yield seemingly conflicting results that can take
years of research and additional studies to
reconcile. Individuals trained in research
methodology understand that observational
studies yield weaker evidence – which needs to
be viewed sceptically – while RCTs yield
stronger evidence that can invalidate weaker evi-
dence. Thus, for a scientifically trained audience,
apparent inconsistencies in the results of obser-
vational and RCT findings may not necessarily
be perceived as ‘conflicting information’. Lim-
ited scientific literacy, however, may prevent the
general public from understanding the hierarchy
of evidence and the differences between correla-
tional and causal studies; as a result, they may
simply perceive such inconsistencies in evidence
as conflicts between equivalent forms of evi-
dence. For example, the public may perceive
conflict between a cross-sectional survey of
50 000 people that finds that coffee is associated
with a lower risk of heart disease and an RCT
with 2500 participants that finds no association.
In contrast, nutritional epidemiologists would
regard these studies as non-comparable from
an evidentiary standpoint and prioritize the
RCT findings. Failure to understand the hier-
archy of scientific evidence may also explain
why attempts to educate the public about
RCTs that found no evidence of a vaccina-
tion–autism link have not made much
headway in diffusing the negative effects of
conflicting information.37
Fraudulent scientific studies can also produce
conflicting information – and perpetuate percep-
tions of conflict – among professional
communities as well as the general public. The
vaccination example given in Table 1 offers an
excellent example of this. In 1998, Wakefield
and colleagues published a paper in which
they claimed that environmental triggers (i.e.
the MMR vaccination) were associated with
gastrointestinal disease and developmental
regression (i.e. autism) in eight of 12 children
studied.38 In 2010, twelve years later, the paper
was officially retracted due to ethical misconduct
and falsified data.39 In 2011, detailed informa-
tion regarding why the findings on the link
between autism and MMR vaccination were
fraudulent was published in BMJ.40 Unfortu-
nately, during the 12 years before the paper was
retracted, the findings were disseminated in
media and online outlets and served as a basis
for the modern antivaccination movement.41 In
fact, one study found that half of antivaccina-
tion websites applaud doctors such as Wakefield
for speaking out against vaccinations.41 Despite
repeated and large-scale efforts to educate the
general public about why MMR vaccination
does not cause autism, the antivaccination
movement remains strong and continues to cite
Wakefield’s retracted study.
Future research directions
Many gaps exist in our understanding of con-
flicting health information. Thus, we are not
well-positioned to help patients and clinicians
manage this growing problem. Moving forward,
we believe a coherent, comprehensive pro-
gramme of research is needed to determine the
prevalence, causes and effects of conflicting
health information and to develop effective
strategies to deal with it. The multifaceted nat-
ure of this phenomenon and its potential effects
calls for a transdisciplinary programme of
research. However, both the challenge and pro-
mise of employing a transdisciplinary team of
scientists (e.g. communication scholars, beha-
vioural decision theorists, health services
researchers) are that they have their own well-
developed theories of how people process infor-
mation and make decisions. These theories may
provide useful lenses for understanding the
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al. 1179
causes and effects of conflicting information;
however, exactly how to optimally integrate
these theories is unclear and represents a funda-
mental research need. For example, theories
from the persuasion literature, including
extended parallel process model42 and the uni-
model43,44, may offer guidance as to how
subjective perceptions (e.g. perceived threat)
may influence processing of conflicting health
information. Additionally, other theories, such
as fuzzy trace theory,45 are applicable to the
study of conflicting health information because
they identify factors (e.g. low health literacy)
that may interfere with information processing.
Finally, theosries from other fields, such as arti-
ficial intelligence, offer potentially useful insights
on how people process and integrate conflicting
information.46–48
Equally important is the need to develop valid
and reliable measures of conflicting health infor-
mation. Some measures exist,4,49,50 but more
work is needed to assess their psychometric
properties and to develop measures that accu-
rately capture conflicting health information in
its many potential manifestations. This initial
psychometric work could then enable basic
research aimed at elucidating the effects of con-
flicting health information on health judgments
and decisions and the mechanisms underlying
these effects. Additional measurement work
should be devoted to developing instruments
that capture the intrapersonal factors (e.g.
beliefs, information needs, perceived salience of
topic) that are likely associated with how indi-
viduals process conflicting information.
Understanding the effects of conflicting health
information would ultimately pave the way for
applied research aimed at translating insights on
the causes and effects of conflicting health infor-
mation into interventions to help individuals
better manage this information. We have pro-
posed several key issues for consideration;
however, there are additional issues related to
study design and data analysis that could perpet-
uate conflicting information. For example, a
single study could result in conflicting informa-
tion if researchers use alternative statistical
methodologies that result in different interpreta-
tions of the data. The fundamental prerequisite
for a comprehensive programme of research on
conflicting health information, however, is
recognition of the phenomenon’s importance
and conceptual clarity about what it entails. This
viewpoint article is offered as a preliminary step
towards these goals.
Sources of funding
Financial support for this research was provided
in part by grants from the National Institutes of
Health. The funding agreement ensured the
authors’ independence in designing the research,
interpreting the data, writing and publishing
the report.
Acknowledgements
DMC’s salary was partially supported by the
National Center for Research Resources and the
National Center for Advancing Translational
Sciences, National Institutes of Health, through
Grant KL2TR000084. RHN acknowledges sup-
port from the Building Interdisciplinary
Research Careers in Women’s Health Grant
(2K12-HD055887) from the Eunice Kennedy
Shriver National Institutes of Child Health and
Human Development, the Office of Research on
Women’s Health and the National Institute on
Aging, administered by the University of Min-
nesota Deborah E. Powell Center for Women’s
Health. NFD acknowledges the generous sup-
port of the U. S. National Science Foundation
(Award#1231231 administered by Decision
Research). PKJH acknowledges the support of
the National Human Genome Research Institute
under the Intergovernmental Personnel Act. The
content is solely the responsibility of the authors
and does not necessarily represent the official
views of the National Center for Advancing
Translational Sciences, National Science Foun-
dation or the National Institutes of Health.
Conflict of interests
The authors have no conflict of interests
to disclose.
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al.1180
References
1 Nagler RH, Fowler EF, Gollust SE. Covering
controversy: what are the implications for women’s
health?Women’s Health Issues, 2015; 25: 318–321.
2 Frosch DL, Moulton BW, Wexler RM et al. Shared
decision making in the United States: policy and
implementation activity on multiple fronts. Zeitschrift
f€ur Evidenz, Fortbildung und Qualit€at im
Gesundheitswesen, 2011; 105: 305–312.
3 Carpenter DM, DeVellis RF, Fisher EB et al. The
effect of conflicting medication information and
physician support on medication adherence for
chronically ill patients. Patient Education and
Counseling, 2010; 81: 169–176.
4 Carpenter DM, Elstad EA, Blalock SJ, DeVellis RF.
Conflicting medication information: prevalence,
sources, and relationship to medication adherence.
Journal of Health Communication, 2014; 19: 67–81.
5 Blendon RJ, Schoen C, DesRoches C, Osborn R,
Zapert K. Common concerns amid diverse systems:
health care experiences in five countries.Health
Affairs, 2003; 22: 106–121.
6 Lim AYN, Ellis C, Brooksby A, Gaffney K. Patient
satisfaction with rheumatology practitioner clinics:
can we achieve concordance by meeting patients’
information needs and encouraging participatory
decision making? Annals of the Academy of Medicine,
Singapore, 2007; 36: 110–114.
7 H€ameen-Anttila K, Nordeng H, Kokki E et al.
Multiple information sources and consequences of
conflicting information about medicine use during
pregnancy: a multinational Internet-based survey.
Journal of Medical Internet Research, 2014; 16:
e60.
8 Squiers LB, Holden DJ, Dolina SE et al. The public’s
response to the U.S. Preventive Services Task Force’s
2009 recommendations on mammography screening.
American Journal of Preventive Medicine, 2011; 40:
497–504.
9 Taplin SH, Urban N, Taylor VM, Savarino J.
Conflicting national recommendations and the use of
screening mammography: does the physician’s
recommendation matter? The Journal of the American
Board of Family Practice, 1997; 10: 88–95.
10 Niederdeppe J, Levy AG. Fatalistic beliefs about
cancer prevention and three prevention behaviors.
Cancer Epidemiology Biomarkers & Prevention, 2007;
16: 998–1003.
11 Han PK, Klabunde CN, Breen N et al.Multiple
clinical practice guidelines for breast and cervical
cancer screening: perceptions of US primary care
physicians.Medical Care, 2011; 49: 139–148.
12 Nagler RH. Adverse outcomes associated with media
exposure to contradictory nutrition messages. Journal
of Health Communication, 2014; 19: 24–40.
13 Eysenbach G. The impact of the Internet on cancer
outcomes. CA: A Cancer Journal for Clinicians, 2003;
53: 356–371.
14 Elstad E, Carpenter DM, Devellis RF, Blalock SJ.
Patient decision making in the face of conflicting medi-
cation information. International Journal of Qualitative
Studies on Health and Well-Being, 2012; 7: 1–11.
15 Vidal L, Shavit M, Fraser A, Paul M, Lleibovici L.
Systematic comparison of four sources of drug
information regarding adjustment of dose for renal
function. BMJ, 2005; 331: 263–265.
16 Mashiach R, Seidman GI, Seidman DS. Use of
mifepristone as an example of conflicting and
misleading medical information on the internet.
BJOG: An International Journal of Obstetrics and
Gynaecology, 2002; 109: 437–442.
17 Mankoff J, Kuksenok K, Kiesler S, Rode JA,
Waldman K. Competing online viewpoints and
models of chronic illness. Paper presented at:
Proceedings of the SIGCHI Conference on Human
Factors in Computing Systems, 2011.
18 Hwang KO, Farheen K, Johnson CW et al. Quality
of weight loss advice on internet forums. The
American Journal of Medicine, 2007; 120: 604–609.
19 Fox S. The social life of health information 2011. Pew
Internet & American Life Project. Washington, DC,
2011. Available at: http://www.pewinternet.org/2011/
05/12/the-social-life-of-health-information-2011/.
20 Hilton S, PetticrewM, Hunt K. Parents’ champions vs.
vested interests: who do parents believe about MMR?
a qualitative study. BMC Public Health, 2007; 7: 42.
21 Shanteau J. Why do experts disagree? In: Green B
(ed.), Risk Behaviour and Risk Management in
Business Life. Dordrecht, The Netherlands: Kluwer
Academic Press, 2000: 186–196.
22 Pollock K, Grime J, Baker E, Mantala K. Meeting
the information needs of psychiatric inpatients: staff
and patient perspectives. Journal of Mental Health,
2004; 13: 389–401.
23 Han PKJ, Moser RP, Klein WMP. Perceived
ambiguity about cancer prevention
recommendations: relationship to perceptions of
cancer preventability, risk, and worry. Journal of
Health Communication, 2006; 11(1S): 51–69.
24 McIntosh A, Shaw CF. Barriers to patient
information provision in primary care: patients’ and
general practitioners’ experiences and expectations of
information for low back pain.Health Expectations,
2003; 6: 19–29.
25 Given LM, Ruecker S, Simpson H, Sadler EB,
Ruskin A. Inclusive interface design for seniors:
image-browsing for a health information context.
Journal of the American Society for Information
Science and Technology, 2007; 58: 1610–1617.
26 Kienhues D, Stadtler M, Bromme R. Dealing with
conflicting or consistent medical information on the
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al. 1181
Web: when expert information breeds laypersons’
doubts about experts. Learning and Instruction, 2011;
21: 193–204.
27 Hibbard JH, Slovic P, Jewett JJ. Informing consumer
decisions in health care: implications from decision-
making research. The Milbank Quarterly, 1997; 75:
395–414.
28 Wegwarth O, Gigerenzer G. Trust-Your-Doctor: A
Simple Heuristic in Need of a Proper Social
Environment. Simple Heuristics in a Social World.
New York: Oxford University Press, 2013.
29 Tversky A, Sattath S, Slovic P. Contingent weighting
in judgment and choice. Psychological Review, 1988;
95: 371.
30 Hsee CK. Elastic justification: how tempting but
task-irrelevant factors influence decisions.
Organizational Behavior and Human Decision
Processes, 1995; 62: 330–337.
31 Han PK. Conceptual, methodological, and ethical
problems in communicating uncertainty in clinical
evidence.Medical Care Research and Review, 2013; 70
(1S): 14S–36S.
32 Kunda Z. The case for motivated reasoning.
Psychological Bulletin, 1990; 108: 480–498.
33 Keselman A, Browne AC, Kaufman DR. Consumer
health information seeking as hypothesis testing.
Journal of the American Medical Informatics
Association, 2008; 15: 484–495.
34 Brewer NT, Edwards AS, O’Neill SC et al.When
genomic and standard test results diverge:
implications for breast cancer patients’ preference for
chemotherapy. Breast Cancer Research and
Treatment, 2009; 117: 25–29.
35 Samuelson W, Zeckhauser R. Status quo bias in
decision making. Journal of Risk and Uncertainty,
1988; 1: 7–59.
36 Merriam-Webster.com. conflicting. 2014. In
Merriam-Webster.com. Retrieved July 14, 2014, from
http://www.merriam-webster.com/dictionary/
conflicting
37 Kahan DM. A risky science communication
environment for vaccines. Science, 2013; 342: 53–54.
38 Wakefield AJ, Murch SH, Anthony A et al.
RETRACTED: ileal-lymphoid-nodular hyperplasia,
non-specific colitis, and pervasive developmental
disorder in children. The Lancet, 1998; 351:
637–641.
39 Caplan AL. Retraction – ileal-lymphoid-nodular
hyperplasia, non-specific colitis, and pervasive
developmental disorder in children. The Weekly
Epidemiological Record, 2009; 84: 301–308.
40 Deer B. How the case against the MMR vaccine was
fixed. BMJ, 2011; 342: c5347.
41 Kata A. A postmodern Pandora’s box: anti-
vaccination misinformation on the Internet. Vaccine,
2010; 28: 1709–1716.
42 Witte K. Putting the fear back into fear appeals: the
extended parallel process model. Communications
Monographs, 1992; 59: 329–349.
43 Kruglanski AW, Chen X, Pierro A et al. Persuasion
according to the unimodel: implications for cancer
communication. Journal of Communication, 2006; 56
(s1): S105–S122.
44 Kruglanski AW, Thompson EP. Persuasion by a
single route: a view from the unimodel. Psychological
Inquiry, 1999; 10: 83–109.
45 Reyna VF, Brainerd CJ. Fuzzy-trace theory: an
interim synthesis. Learning and Individual Differences,
1995; 7: 1–75.
46 Benferhat S, Kaci S, Le Berre D, Williams M-A.
Weakening conflicting information for iterated
revision and knowledge integration. Artificial
Intelligence, 2004; 153: 339–371.
47 Lin J. Integration of weighted knowledge bases.
Artificial Intelligence, 1996; 83: 363–378.
48 Cantwell J. Resolving conflicting information. Journal
of Logic, Language and Information, 1998; 7: 191–220.
49 Nagler RH, Hornik RC. Measuring media exposure
to contradictory health information: a comparative
analysis of four potential measures. Communication
Methods and Measures, 2012; 6: 56–75.
50 Han PK, Reeve BB, Moser RP, Klein WM. Aversion
to ambiguity regarding medical tests and treatments:
measurement, prevalence, and relationship to
sociodemographic factors. Journal of Health
Communication, 2009; 14: 556–572.
51 McLean HQ, Fiebelkorn AP, Temte JL, Wallace GS.
Prevention of measles, rubella, congenital rubella
syndrome, and mumps, 2013: summary
recommendations of the Advisory Committee on
Immunization Practices (ACIP).MMWR -
Recommendations and Reports, 2013; 62: 1–34.
52 Taylor B, Miller E, Farrington C et al. Autism and
measles, mumps, and rubella vaccine: no
epidemiological evidence for a causal association. The
Lancet, 1999; 353: 2026–2029.
53 Beck S. The Daily Mail. Scientists fear MMR link to
autism. Available at: http://www.dailymail.co.uk/
news/article-388051/Scientists-fear-MMR-link-
autism.html, accessed 28 May 2006.
54 Folb PI, Bernatowska E, Chen R et al.A global
perspective on vaccine safety and public health: the
Global Advisory Committee on Vaccine Safety.
American Journal of Public Health, 2004; 94: 1926–1931.
55 Tan B, Shainoor I. Statement onMeasles-Mumps-
Rubella-Varicella Vaccine. National Advisory
Committee on Immunization (NACI).Canada
Communicable Disease Report, 2010; 36ACS-9: 1–22.
56 ACIP. Measles prevention: recommendations of the
Immunization Practices Advisory Committee (ACIP).
Morbidity and Mortality Weekly Report, 1989,
38(S9); 1–18.
ª 2015 The Authors. Health Expectations Published by John Wiley & Sons Ltd
Health Expectations, 19, pp.1173–1182
Conflicting health information, D M Carpenter et al.1182