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Inductive reasoning guides public perception of Ebola risk
Inductive reasoning may influence how people react to public health messaging about the risk for acquiring Ebola virus, according to two recent studies from the University of Sydney and Texas Tech University.
“Inductive reasoning is all about how people generalize from their experience and knowledge to other, novel situations,” Micah Goldwater, PhD, a lecturer at the University of Sydney’s School of Psychology and an investigator in the studies, told Infectious Disease News. “Given what you know and what you’ve experienced, you might make predictions about other situations you haven’t encountered yet.”
Within the context of zoonotic disease transmission, inductive reasoning might apply to a person’s knowledge about dog or bat bites. If the person is aware that other similar animals may transmit diseases such as rabies or Ebola, they will likely be more concerned about being infected from a bite. This reaction occurs because the person has generalized their knowledge about other animals to the one that has bitten them.
“This project was specifically focused on a subfield within inductive reasoning — category-based induction,” Goldwater said. “In category-based induction, you draw conclusions based on category knowledge. For example, if you learn that a poodle has a certain property, how likely are you to generalize that to a different animal? In this case, you’re probably much more likely to assume that a German Shepherd has that same property vs. a lion.”
Goldwater and colleagues evaluated risk perception by asking participants about various animals and their potential for transmitting disease.
“The first part was looking at people’s beliefs about which animals transmit disease, and which animals transmitted disease to each other,” he said. “Then we looked at how they might be more likely to call a doctor after an interaction with an animal that wasn’t one of the animals we asked about explicitly, but their notion of it was that it was in a similar category.”
Premise diversity
To understand how inductive reasoning might apply to Ebola risk messaging, the researchers analyzed whether people apply knowledge about the types of animals that are vulnerable to a disease when assessing their own risk of contacting a specific type of animal. This was determined through various means, such as whether study participants would be likely to report certain animal bites to a medical professional, and their beliefs about the safety of different kinds of meat.
Goldwater said the WHO and CDC offer different public health communications about Ebola. Specifically, the CDC listed only bats and nonhuman primates as reservoirs of Ebola, whereas WHO also included porcupines and forest antelope on their list.
The study revealed variations between the two messages in a concept called premise diversity. Goldwater explained that in premise diversity, if a person is presented with a more diverse group of premises that share a certain property, they are more likely to generalize.
“In the basic experiment world, if I tell you, ‘A lion has property X and a kangaroo has property X. Do all mammals share property X?’ You’re probably more likely to say ‘yes’ than if I said ‘A lion has property X and a tiger has property X. Do all mammals share property X?’ Because a lion and a tiger are so similar, they don’t cover that much of the overall space of the category.”
The researchers found that listing a broader range of potential sources of Ebola resulted in an increased tendency to report animal bites and prompted wariness about wild game meat. This indicates that inductive reasoning can be used to regulate public perception of zoonosis risk, they said.
Because the WHO warning listed porcupines and forest antelopes along with bats and nonhuman primates, their messaging suggested that Ebola could be transmitted by a larger variety of animals.
“We didn’t actually ask them about Ebola transmission, necessarily, but we asked them, ‘Given that warning about Ebola, how likely are you to eat bushmeat? How safe do you perceive bushmeat to be?’” Goldwater said. “Those who had the WHO warning, which gave a greater variety of animals you could catch Ebola from, were more likely to think bushmeat was unsafe, even though it wasn’t of that specific animal we mentioned.”
‘The span of what is possible’
Goldwater said the fact that the WHO warning was more likely to lead a participant to avoid bushmeat would likely be beneficial to public health.
“I read not long ago that the illegal bushmeat trade is one of the most likely sources that the next pandemic is going to come out of,” he said. “There is a trade from Africa into the U.K., and this international pathway of using wild animal meat has potential for huge disease spread.”
Goldwater acknowledged that it is important to strike a balance in public health messages to avoid unnecessarily inducing panic. However, he emphasized the need to include as wide a variety of animals as is relevant.
“Listing just primates and bats when there are actually other kinds of animals that can transmit it is not great,” he said. “You don’t have to list every individual animal, but you want to cover all the different subtypes. You want to extend the variety that shows the whole span of what is possible.”
Inductive reasoning is especially beneficial as a way of interpreting brief messages in a short period of time, he said.
“With this messaging, you have a very small amount of time and space to get these points out,” he said. “No one’s going to sit there and read a long article about how Ebola can be transmitted. They just see the warning sign in the airport. You have three sentences to get them.” – by Jennifer Byrne
Disclosure: Goldwater reports no relevant disclosures.
For more information:
Micah Goldwater, PhD, can be reached at micah.goldwater@sydney.edu.au.