Neuroscience
Unwarranted public anxiety about vaccinations can have deadly consequences. Unfortunately, the challenge of communicating health risks is full of psychological complexity. A new German study brings this home, showing how messages that deny vaccination health risks in unequivocal terms can backfire, actually increasing concern among parents.
Cornelia Betsch and Katharina Sachse recruited 115 participants online (mean age 34; 34 per cent were male; 43 per cent had one or more children). The participants were asked to imagine they were a parent of an 8-month-old and to read an account of a fictitious illness Phyxolitis pulmonis. They were further told that their paediatrician had advised vaccinating their child against this condition. Next, the participants were presented with anti-vaccine statements that they'd ostensibly found on the internet (e.g. "Multiple vaccines overwhelm the infant's immune system"). Finally, they read statements of reassurance about the vaccine, which claimed any risks were low - half the participants read weak versions (e.g. "There is only sporadic evidence that repeated vaccinations overwhelm the immune system") and half read strong versions of these statements (e.g. "there is no evidence that repeated vaccinations overwhelm the immune system").
The key finding here was that participants who read the strong statements of reassurance actually reported greater perceptions of risk afterwards, and lower intentions to vaccinate their child. This effect was heightened among participants who had a preference for complementary medicine. Results didn't vary according to whether participants were a parent in real life or not.
A second study with a further 119 participants was similar but this time the source of the reassuring statements was varied, either being from a pharmaceutical company (untrusted) or from a government health department (a trusted source). Again, strong statements of reassurance backfired, increasing risk perception and reducing vaccination intentions, but only if those statements came from an untrusted source. Again, this paradoxical effect was stronger among participants who favoured complementary medicine.
This study can't reveal why the paradoxical effect occurs. However, one possibility proposed by Betsch and Sachse is that an extreme statement of no risk is more attention-grabbing, which only serves to highlight the possibility that risk is an issue. Another potential explanation is that people look for ways to combat claims they disagree with, and if those claims are stated more strongly then that encourages people to marshal even stronger counter-claims of their own.
The results have obvious implications for real-life risk communication. "Especially when organisations lack complete knowledge about how much trust the public puts in them, optimal risk negation is likely to profit from moderate rather than extreme formulations," the researchers said.
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Betsch, C., and Sachse, K. (2012). Debunking Vaccination Myths: Strong Risk Negations Can Increase Perceived Vaccination Risks. Health Psychology DOI: 10.1037/a0027387
Previously on the Research Digest:
How to promote the MMR vaccine.
The psychological barriers facing MMR promotion campaigns.
Post written by Christian Jarrett for the BPS Research Digest.
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Neuroscience
Strong reassurances about vaccines can backfire
Cornelia Betsch and Katharina Sachse recruited 115 participants online (mean age 34; 34 per cent were male; 43 per cent had one or more children). The participants were asked to imagine they were a parent of an 8-month-old and to read an account of a fictitious illness Phyxolitis pulmonis. They were further told that their paediatrician had advised vaccinating their child against this condition. Next, the participants were presented with anti-vaccine statements that they'd ostensibly found on the internet (e.g. "Multiple vaccines overwhelm the infant's immune system"). Finally, they read statements of reassurance about the vaccine, which claimed any risks were low - half the participants read weak versions (e.g. "There is only sporadic evidence that repeated vaccinations overwhelm the immune system") and half read strong versions of these statements (e.g. "there is no evidence that repeated vaccinations overwhelm the immune system").
The key finding here was that participants who read the strong statements of reassurance actually reported greater perceptions of risk afterwards, and lower intentions to vaccinate their child. This effect was heightened among participants who had a preference for complementary medicine. Results didn't vary according to whether participants were a parent in real life or not.
A second study with a further 119 participants was similar but this time the source of the reassuring statements was varied, either being from a pharmaceutical company (untrusted) or from a government health department (a trusted source). Again, strong statements of reassurance backfired, increasing risk perception and reducing vaccination intentions, but only if those statements came from an untrusted source. Again, this paradoxical effect was stronger among participants who favoured complementary medicine.
This study can't reveal why the paradoxical effect occurs. However, one possibility proposed by Betsch and Sachse is that an extreme statement of no risk is more attention-grabbing, which only serves to highlight the possibility that risk is an issue. Another potential explanation is that people look for ways to combat claims they disagree with, and if those claims are stated more strongly then that encourages people to marshal even stronger counter-claims of their own.
The results have obvious implications for real-life risk communication. "Especially when organisations lack complete knowledge about how much trust the public puts in them, optimal risk negation is likely to profit from moderate rather than extreme formulations," the researchers said.
_________________________________
Betsch, C., and Sachse, K. (2012). Debunking Vaccination Myths: Strong Risk Negations Can Increase Perceived Vaccination Risks. Health Psychology DOI: 10.1037/a0027387
Previously on the Research Digest:
How to promote the MMR vaccine.
The psychological barriers facing MMR promotion campaigns.
Post written by Christian Jarrett for the BPS Research Digest.
- Researchers Say They've Found A Way To Combat Anti-vaccine Attitudes, But Is It Premature To Celebrate?
By guest blogger Simon Oxenham Over recent years, measles has once again become a public health crisis in the western world as a result of growing anti-vaccination movements in the UK and the US. This is an enormous problem because the success of vaccination...
- The Psychological Barriers Facing Mmr Promotion Campaigns
A focus group study of parents' attitudes towards interventions promoting uptake of the MMR vaccine suggests it is better for health advice to be seen as independent from government. The findings come after the General Medical Council ruled yesterday...
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The skies are crowded with planes, our sclerotic roads clogged with millions of cars – when will we wake up to the urgency of climate change? Spreading the word about the effect climate change will have on human health. That could be the key. A group...
- Why Do People Use Complementary Medicine?
From acupuncture to homeopathy, complementary medicine is increasingly popular despite continuing doubts about its effectiveness. Now Felicity Bishop and colleagues have used an internet survey to see if people who use complementary medicine tend to think...
- Noise Increases The Risk Of Having A Heart Attack
Too much noise, such as the sound of passing traffic, can increase the risk of heart attack in men by 50 per cent and in women by up to threefold. That’s according to a team of German researchers who interviewed 4,115 hospital inpatients, about half...