Let’s say that one day, you wake up incredibly itchy. A doctor recommends two drugs – one natural and one synthetic – to help with the scratching. Or, you start having intense mood swings, and you go to your doctor, who presents you with the option of taking a natural or a synthetic drug.

Which do you pick in each situation, and does the answer change if you’re treating your body as opposed to your mind?

We are bombarded with the word “natural” anytime we buy groceries, supplements, beauty products, household items, wine or cigarettes. People believe that “natural” products, foods and medicines are safer, healthier – and just better. This is called the “natural preference”, or natural-is-better bias. When people are told that the function of two products are identical, they still prefer the natural one. This bias shows up in our partiality to natural light and natural talent.

A recent study in the Journal of Consumer Psychology added another layer of complexity: people are more likely to reach for what’s “natural” when treating what they consider to be a psychological condition, compared to a physical one. People gravitated towards a natural remedy for both itchiness and mood swings, but were more inclined to do so for the latter.

The research offered a new explanation for why people want what’s “natural”: they are worried about synthetic drugs affecting their “true self”.

“It’s not only about the external characteristics of whatever the product is, but also a concern about, ‘How does it affect me?’” said David Gal, a professor of marketing at the University of Illinois at Chicago, and co-author of the paper.

Across six experiments, Gal and the first author, Tianyi Li, found a strong preference for natural medications when treating psychological problems. Gal said they were aware of the past research on the natural preference, and had wondered if the bias would be exacerbated when it came to mental health conditions. What turned out to be more striking was the reason the natural preference was heightened.

“There was this sense that synthetic medicine could change me more than the natural, and I don’t want to change myself,” Gal said.

This ties the natural-is-better bias for the first time to another area of psychological research: the true self. The true self is a belief that has been shown to be widely held. The true self is not just your “self”, but what you consider your core essence, the heart of what makes you who you are. People consistently say that some of the things they do or some of their traits are “truer” than others (usually the morally good ones). To be clear: there’s not really a discrete part of your “self” that you can point to that is more “true”, so the true self can be thought of more as a folk intuition that reflects how people think about identity.

But a person’s conception of their true self is not trivial, even if it’s based on a hunch. Rebecca Schlegel, a social personality psychologist at Texas A&M, has found that people feeling connected to, or alienated, from what they consider to be their “true self” is intimately related to wellbeing.

This prompts some deeper questions: do people consider aspects of their mental suffering as parts of their true selves, even when they are distressing? Take “Matt”, a case from the paper, who is feeling depressed. After taking synthetic medication, “his feelings and emotions have undergone a radical transformation, leading to a state of joy and carefreeness”. Does this new happiness represent Matt’s true self? Or is the medication covering up who he really is? These more philosophical impacts of a mental health medication are rarely explored, Schlegel said.

If people believe synthetic drugs alter their true selves, it might lead them to avoid medications and to feel conflicted about a medication’s effects, even when those effects are positive. (Factoring in the true self could also offer a new perspective on how people regard psychedelic-assisted therapy, where people report saying they have gained more insight into their self-identity.)

Though the “true self” is not an objective measure, Schlegel said, what we consider to be our authentic selves can drive our decision-making if we are beholden to ideas about the true self or naturalness, especially when treating the mind.

“It can be puzzling for healthcare providers when some patients are hesitant to take prescribed antidepressants but more willing to self-medicate with over-the-counter supplements that are made of natural ingredients,” Li said. “These patients might feel misunderstood in their need to preserve their core selves.”

Still, this preference is a bias, and natural doesn’t always equate to safer or better, Li said. In the US, supplements aren’t regulated by the FDA, and natural compounds might have more impurities than ones that are synthetically derived. “Not taking something synthetic can prevent people from getting the treatment they need,” Gal added.

The consequences of the natural preference are more important when it comes to medicine as opposed to, say, picking natural crackers over Cheez-Its, said Brian Meier, a psychologist at Gettysburg College who studies the natural preference. Early in the pandemic, people with a stronger naturalness bias with drugs reported being less willing to get a Covid-19 vaccine, and after the vaccine was widely available, people with a stronger naturalness bias were less likely to have the shot.

But it’s not as simple as people making “wrong” decisions in favor of natural options. People don’t only use the word natural to mean safer – it’s taken on a larger significance.

“‘Nature’ has become a stand-in for God, and ‘natural’ synonymous with ‘holy’,” wrote Alan Levinovitz, a professor of religion at James Madison University, in his book Natural: The Seductive Myth of Nature’s Goodness.

Levinovitz published the book three years ago, and has since continued to mull over why people use naturalness as a justification for their choices and preferences. “People, myself included, should really introspect about what it is that they value when they value the ‘natural’ thing,” Levinovitz said. “Especially, ask yourself: is there something outside of efficacy and safety that this natural intervention is connecting me to?”

This is where he’s landed: other people can feel forced to assert that naturalness is better when their actual complaints aren’t considered valid by medicine, doctors or others in their life. A recent survey found that 52% of people in the US feel their symptoms are “ignored, dismissed or not believed”.

“Then they have to recalibrate their whole argument so that it fits into the kind of scientific, materialist vocabulary and reasoning,” Levinovitz said.

For example, feeling empowered while giving birth is valuable for many people, alongside being safe. But empowerment during birth is not as easy to measure, and so people might use the concept of naturalness – for example, stating a preference for a “natural birth” – when advocating for a certain type of delivery.

“Maybe we need to open up space in the discussion of empirical truths about health and healing, for value claims that aren’t easily quantified or measured,” Levinovitz said.

Holding a bias toward natural items is not going to cause issues in every case. But, especially given the fact that it may affect high-stakes medical decisions, it’s worth pausing to consider and learn what the concept means to you. “I tend to grab natural peanut butter without thinking too much,” Meier said. “Yet, when we slow down and try to understand a choice, we might be able to think a bit more deeply about our reasoning.”