You’ve probably heard at least one story in the past couple of years about how exposure to nature is good for your mental health.
That message is supported by numerous studies suggesting that getting outside and spending some time around plants – or even looking at photographs of a forest, in a pinch – can boost people’s mood and improve mental wellbeing.
But a new study from researchers at the University of Vermont, US, highlights a gaping issue in this field. This scientific evidence is primarily based on studies of wealthy, white people – raising the question of how applicable it really is to the rest of the world.
“This field has great potential to address urgent issues – from the global mental health crisis to sustainability efforts worldwide – but to do so, we must better reflect the diversity of world’s populations, cultures and values,” says lead author Carlos Andres Gallegos-Riofrio.
Lower-income countries and non-white ethnicities underrepresented
Looking at 174 peer-reviewed studies of the relationship between nature and mental wellbeing published between 2010 and 2020, Gallegos-Riofrio and his colleagues found that over 90% of the studies took place in high-income nations in North America, Europe, Oceania and East Asia.
Less than 4% of the studies were conducted in medium-income countries such as India, and none in low-income countries. The entire continents of Africa and South America were represented by only one study each.
Only 25% of the studies clearly reported data on participants’ ethnicity. Among these, 82% included participants identified as “white”. The next most common reported ethnicity category was “other” (66%), followed by “Asian” (41%). Relatively few studies included participants identified as Indigenous, Hispanic/Latino, Middle Eastern or Pacific Islander. Only two focused on groups who are ethnic minorities in their country of residence: one on African-Americans and one on Indigenous people in Canada.
The researchers also analysed how “nature” was understood or defined in this scientific literature. They found that most studies from Western countries like the US, Canada, Australia and European countries focused on nature in terms of “greenspace” – such as parks – or sometimes “bluespace” such as lakes or oceans. The authors argue that their analysis reveals a relatively narrow and human-centric conception of nature, rather than a more holistic view that emphasises humans’ relationships with and responsibility to the rest of the natural world.
Learn more: Is nature really accessible?
Why does improving diversity matter for science?
The new study was inspired by a 2012 analysis of studies in the behavioural sciences, which coined the term “WEIRD” – Western, Educated, Industrialised, Rich and Democratic – to describe the bias they found in the literature. That analysis cautioned that sweeping generalisations about human psychology and behaviour were being made based on a small and unrepresentative sample.
“Members of WEIRD societies, including young children, are among the least representative populations one could find for generalising about humans,” wrote the authors of the 2012 study.
Now, Gallegos-Riofrio and colleagues argue that a similar problem applies to studies of nature and mental health. Researchers and funding bodies should make greater efforts to include and collaborate with more diverse participants, and move focus away from rich and industrialised countries, they say.
“We need all cultures working together to tackle the global emergencies we face,” says co-author Amaya Carrasco, a graduate student at the University of Vermont. “That requires understanding what’s universal about the human-nature relationship, and what is culturally specific.”
Improving the diversity of research teams themselves, and better training in cross-cultural and culturally sensitive research, are among the recommendations suggested in the paper.
“We hope our study is wake-up call for this promising field that sparks positive change,” says co-author Rachelle Gould, also of the University of Vermont. “A more inclusive and diverse field that embraces the research needs of the global community – and the full spectrum of ways that humans interact with the non-human world – will ultimately be more impactful.”