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August 04, 2015

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Study: vaccine skeptics persuadable—if you don’t say they’re wrong

Aug. 4, 2015
Courtesy of UCLA
and World Science staff

Many peo­ple who are skep­ti­cal of vac­ci­nat­ing their chil­dren can be coaxed to do so—but only if the ar­gu­ment is pre­sented in a way that does­n’t di­rectly sug­gest they’re wrong, psy­chol­o­gists re­port in a new stu­dy.

The is­sue is es­pe­cially im­por­tant, they add, be­cause the num­ber of mea­sles cases in the Un­ited States tripled from 2013 to 2014, an event linked to a trend of par­ents re­fus­ing to vac­ci­nate their chil­dren.

What does­n’t change par­ents’ minds? Tell­ing them their fear of vac­cina­t­ions is mis­tak­en and un­in­formed, the study found—that just leads them to dig in.

What does work? Simply re­mind­ing them that mea­sles is a ter­ri­ble dis­ease and that they can pro­tect their chil­dren by vac­ci­nat­ing them.

“It’s more ef­fec­tive to ac­cen­tu­ate the pos­i­tive rea­sons to vac­ci­nate and take a non­con­fronta­t­ional ap­proach… than di­rectly try­ing to coun­ter” an­ti-vac­cine per­cep­tions, ex­plained Keith Holyoak of the Un­ivers­ity of Cal­i­for­nia Los An­ge­les, a sen­ior au­thor of the stu­dy. 

The re­search ap­pears in this week’s on­line early edi­tion of the jour­nal Pro­ceed­ings of the Na­t­ional Acad­e­my of Sci­ences.

The study re­cruited 315 adult par­ti­ci­pants from through­out the Un­ited States. In­i­tial­ly, about one-third held very fa­vor­a­ble at­ti­tudes to­ward vac­cines; the rest ex­pressed at least some skep­ti­cism, in­clud­ing a die­hard one in 10 who held “very neg­a­tive at­ti­tudes” to­ward vac­cines.

All 315 par­ti­ci­pants were ran­domly di­vid­ed in­to three groups.

One group read ma­te­ri­al from the U.S. Cen­ters for Dis­ease Con­trol and Pre­vention say­ing all chil­dren should be vac­ci­nated for mea­sles, mumps and ru­bel­la; ex­plain­ing that the vac­cine for those dis­eases is safe and ef­fec­tive; and that while some par­ents wor­ry the vac­cine causes au­tism, many sci­en­tif­ic stud­ies have shown that no such link ex­ists.

This ap­proach changed no minds, the psy­chol­o­gists said.

An­oth­er group read ma­te­ri­als that de­scribed the dan­gers of mea­sles, mumps and ru­bel­la, and ex­plained how a vac­cine can pre­vent these dis­eases. The ma­te­ri­als in­clud­ed pho­tographs of chil­dren with these dis­eases.

The group al­so read a par­a­graph by a moth­er named Megan Camp­bell, whose 10-month-old son suf­fered a life-threatening bout of mea­sles. “We spent three days in the hos­pi­tal fear­ing we might lose our ba­by boy,” Camp­bell wrote. “He could­n’t drink or eat, so he was on an IV, and for a while he seemed to be wast­ing away.”

Among group mem­bers who were skep­ti­cal about or very op­posed to vac­cines, this last ap­proach substan­ti­ally in­creased sup­port for vac­cina­t­ion, the re­search­ers re­ported.

“There was a rea­son we all got vac­ci­nated: Mea­sles makes you very sick. That gets for­got­ten in the po­lar­iz­ing de­bate on wheth­er the vac­cine has side ef­fects,” Holyoak said.

Sup­port­ers and op­po­nents of vac­cines can find com­mon ground, the re­search­ers added.

“Peo­ple who are skep­ti­cal about vac­cines are con­cerned about the safe­ty of their chil­dren,” said Der­ek Pow­ell, a UCLA grad­u­ate stu­dent in psy­chol­o­gy and co-lead au­thor of the stu­dy. “They want their kids to be healthy. That’s al­so what doc­tors wan­t.”

Peo­ple tend to dig in when you chal­lenge their be­liefs, Pow­ell said.

The study has broader im­plica­t­ions for per­suad­ing skep­tics on a wide range of is­sues, the au­thors added. Fight­ing a mis­con­cep­tion head-on sel­dom changes minds, said Holyoak, who con­ducts re­search on learn­ing, rea­soning, knowl­edge and cre­ati­vity.

“Try to find com­mon ground, where pos­si­ble, and build on that,” he said.

While some peo­ple hold very ex­treme an­ti-vac­cina­t­ion be­liefs, many more have heard that vac­cines are con­tro­ver­sial and could be per­suaded ei­ther way, Holyoak said. “They’re per­suad­a­ble by the pos­i­tive ar­gu­ment, but not by the head-on at­tack,” he said.

The re­search­ers found no dif­fer­ence be­tween par­ents and non-par­ents in the stu­dy. “They were the same at pre-test and were af­fect­ed in ex­actly the same way,” Pow­ell said.

The re­search­ers said there may be even more ef­fec­tive ways to in­crease sup­port for vac­cina­t­ion, such as by show­ing a vi­deo with fam­i­lies and doc­tors tak­ing the pos­i­tive ap­proach. “Our ob­served ef­fect is probably the low end of what can be achieved,” Pow­ell said.


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Many people who are skeptical of vaccinating their children can be coaxed to do so—but only if the argument is presented in a way that doesn’t directly suggest they’re wrong, psychologists report in a new study. The issue is especially important, they add, because the number of measles cases in the United States tripled from 2013 to 2014, an event linked to a trend of parents refusing to vaccinate their children. What doesn’t change parents’ minds? Telling them their fear of vaccinations is mistaken and uninformed, the study found—that just leads them to dig in. What does work? Simply reminding them that measles is a terrible disease and that they can protect their children by vaccinating them. “It’s more effective to accentuate the positive reasons to vaccinate and take a nonconfrontational approach… than directly trying to counter” anti-vaccine perceptions, explained Keith Holyoak of the University of California Los Angeles, a senior author of the study. The research appears in this week’s online early edition of the journal Proceedings of the National Academy of Sciences. The study recruited 315 adult participants from throughout the United States. Initially, about one-third held very favorable attitudes toward vaccines; the rest expressed at least some skepticism, including a diehard one in 10 who held “very negative attitudes” toward vaccines. All 315 participants were randomly divided into three groups. One group read material from the U.S. Centers for Disease Control and Prevention saying all children should be vaccinated for measles, mumps and rubella; explaining that the vaccine for those diseases is safe and effective; and that while some parents worry the vaccine causes autism, many scientific studies have shown that no such link exists. This approach changed no minds, the psychologists said. Another group read materials that described the dangers of measles, mumps and rubella, and explained how a vaccine can prevent these diseases. The materials included photographs of children with these diseases. The group also read a paragraph by a mother named Megan Campbell, whose 10-month-old son suffered a life-threatening bout of measles. “We spent three days in the hospital fearing we might lose our baby boy,” Campbell wrote. “He couldn’t drink or eat, so he was on an IV, and for a while he seemed to be wasting away.” Among group members who were skeptical about or very opposed to vaccines, this last approach substantially increased support for vaccination, the researchers reported. “There was a reason we all got vaccinated: Measles makes you very sick. That gets forgotten in the polarizing debate on whether the vaccine has side effects,” Holyoak said. Supporters and opponents of vaccines can find common ground, the researchers added. “People who are skeptical about vaccines are concerned about the safety of their children,” said Derek Powell, a UCLA graduate student in psychology and co-lead author of the study. “They want their kids to be healthy. That’s also what doctors want.” People tend to dig in when you challenge their beliefs, Powell said. The study has broader implications for persuading skeptics on a wide range of issues, the authors added. Fighting a misconception head-on seldom changes minds, said Holyoak, who conducts research on learning, reasoning, knowledge and creativity. “Try to find common ground, where possible, and build on that,” he said. While some people hold very extreme anti-vaccination beliefs, many more have heard that vaccines are controversial and could be persuaded either way, Holyoak said. “They’re persuadable by the positive argument, but not by the head-on attack,” he said. The researchers found no difference between parents and non-parents in the study. “They were the same at pre-test and were affected in exactly the same way,” Powell said. The researchers said there may be even more effective ways to increase support for vaccination, such as by showing a video with families and doctors taking the positive approach. “Our observed effect is probably the low end of what can be achieved,” Powell said.