A 2015 survey found that 88 percent of American scientists believe genetically modified foods are safe, but only 37 percent of the general public feel the same way.  The PEW Research Centre, the institution that conducted the survey, which covered a variety of science issues, noted that this is the “largest opinion difference between the public and scientists.”

This kind of data drives the scientific community a little nuts, mostly because the public’s views seem so far removed from what the best available evidence actually says.  If we could just clearly communicate the evidence and increase scientific literacy, the thinking often goes, the public would behave more rationally.

Alas, research has consistently shown that bombarding the public with more and more scientific facts usually doesn’t do the trick.  You can’t change minds with evidence alone.

Of course, this is because many of these kinds of food and health behaviours – including things like eating organic or going gluten-free – often have little to do with what the science actually says about the risks and benefits. But they do relate to the Prius, celebrities and my immaculately shaved legs.

Bear with me. This will (I hope) make a bit of sense.

Let’s start with the relevance of Toyota’s clumsy looking hybrid.  This best-selling car delivers great mileage and promises to help its owners reduce their carbon footprint.  And while these are fine features, economists have suggested that its popularity hinges more on the image it projects than on its environmental benefits.

Driving a Prius tells the world what kind of person you are.  It is a form of self-expression known as the “Prius effect.”  A 2011 study by economists Steven and Alison Sexton found that consumers are willing to pay thousands more for the ugly Prius (yup, this car isn’t going to win any beauty contests) simply to signal, through an act that has been called conspicuous conservation, their environmental bona fides.  This is one reason it is so ugly. It shows the world you are truly sacrificing (“I could be driving a Ferrari!”) for a good cause.

Our decisions are governed less by rational calculation and more by tribal affiliation than we might like to think.

The same thing happens with food and nutrition choices.  There are innumerable social, economic and cultural factors that influence how and what we eat.  It is a phenomenally complex human behaviour. But there is also little doubt that our food choices serve as a powerful form of self-expression.  Eating organic, going gluten-free, using supplements or avoiding GMOs — all behaviours associated with science that can generously be described as “contested” — is one way to indicate how we want to be identified by others.  At the risk of sounding glib, these choices are, at least in part, personal style decisions.  Food as fashion.

And research tells us that this can be a powerful force, one that can impact a wide range of eating decisions and perceptions. Research by Brian Wansick’s group at Cornell University, for example, found that a significant predictor of a particular food choice (in this 2014 study they were exploring food fears and avoidance) was the desire to have the relevant food-related decision known by their friends and peers.  In other words, a food-related Prius effect was operating.

Similar psychological forces can impact how we perceive the taste of food.  A 2015 study by Boyka Bratanova and colleagues found that many people believe organic food tastes better simply because it is perceived to be ethically superior to nonorganic food.  This taste expectation, the researchers found, enhances the actual taste experience, thus reinforcing the original expectations.  The moral satisfaction of eating in a way that is perceived to be ethical casts a halo effect over the food’s properties. This happens even though blind taste tests have found that organic food does not, in general, taste better than conventionally grown food.

So, what is the role of celebrities in this story?

Research has consistently demonstrated that celebrities can have a profound impact on health and lifestyle decisions.  And that influence can be subtle and covert.

You may think of Gwyneth Paltrow as a less than credible source on the dangers of GMOs or the benefits of eating organic.  You may have your doubts about Katy Perry as a science-informed expert on nutritional supplements and detox diets.  But celebrities like Gwyneth and Katy have an absolutely massive cultural footprint.  And their views on these and other health issues help to establish the cultural relevance of the related behaviours. Gwyneth may not be a scientist, but she projects a powerful and, I must admit, fabulous image that shapes and reinforces what a particular food choice projects to the world ­— including the food’s ethical significance.

Thus, celebrities help to establish the bounds and rules of particular reference groups. And these rules often have little to do with the relevant science.

This is one of the reasons that the same people who deride climate-change deniers for their scientific ignorance can also hold strong — and scientifically questionable — views about, for instance, the alleged health dangers of GMOs.  There is an identity package that must be satisfied, one that includes the embrace of climate change science but the rejection of the equally strong scientific consensus around the safety of GMOs.

These observations undoubtedly sound a bit patronizing, as most people likely feel their choices are well informed and have absolutely nothing to do with celebrity culture.  But we should not underestimate the power of our cognitive biases to sway our reading of the available evidence. Once a particular choice becomes part of our identity package, it is easy to find arguments and “evidence” to confirm our views.  Indeed, celebrities can perform an important role in this context. Celebrities are everywhere and thus they play to our availability and confirmation biases — our well established tendencies to, among other things, see, find and interpret information in a way that confirms preconceived beliefs and attitudes.

And it must also be emphasized that we all engage in these kinds of evidence-free acts of personal branding.  And this brings me to my shaved legs.

I have been seriously into cycling for more than 20 years. And serious cyclists shave their legs. But despite what most cycling enthusiasts assert (“it makes you more aerodynamic!”) there is absolutely no good, evidence-based reason for less-than-pro cyclists to shave their legs, especially if you are an aging, slow wannabe like me.  It is, more than anything, a fashion decision. It is a form a self-expression. It signals to the world that I want to be perceived as belonging to the cycling community, even though that isn’t really my conscious intent (and it probably just looks silly).

Recognizing the complex cultural forces that shape food choices and the perceptions of the relevant science can inform public engagement and food literacy efforts.  It also provides insight into why it is so tough to change people’s views, even in the face of strong scientific consensus.

Photo: Helga Esteb / Shutterstock.com