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Key points
- Our physical environments produce reliable changes in our brains and behavior, for better or worse.
- Heat stress is associated with increased aggression and neighborhood crime rates.
- Access to nature is associated with improved mental and physical health.
I recently had the pleasure of interviewing neuroscientist Kim Meidenbauer on the Nature and Nurture Podcast. We spoke about her research on how physical environmental stressors influence our brains, emotions, and behaviors.
Heat and Violence
One such physical stressor is heat stress. Research has shown that heat waves are associated with reduced cognitive functioning in individuals without reliable access to air-conditioning (which disproportionately impacts socioeconomically disadvantaged neighborhoods; Cedeño Laurent et al., 2018). Extreme summer heat has also been shown to be linked to increased aggression and crime rates (Baron, 1972; Baron and Bell, 1976; Anderson et al., 1995; Anderson et al., 2001).
I asked Meidenbauer whether these findings are due to the heat itself, or to being cooped up indoors during heat waves. The answer seems to be both.
During the COVID-19 lockdowns, rates of domestic abuse rose dramatically (Piquero et al., 2021). There was nothing in the virus that made people more aggressive. It was all a result of the stress of social isolation.
Something similar could be going on with heat stress. If people lock themselves indoors when it’s too hot to go outside, even if they have air-conditioning, the self-isolation could increase irritability and rates of aggression within the home.
Of course, this wouldn’t explain increased crime rates if heat itself had no effect on our moods. Research has shown that extreme heat is associated with worse moods in the summer, which may include irritability and aggression (Keller et al., 2005).
If this is true, one would hypothesize that socioeconomically disadvantaged areas without air-conditioning, swimming pools, or other cool-down luxuries, would have the highest rates of violent crime during heat waves. And that is exactly the case (Gronlund, 2014).
Positive Effects of Nature
Meidenbauer’s research on how the environment influences our brains and behavior also has a positive side. While physical stressors such as heat exposure predict negative outcomes, there are also protective environmental factors that predict positive outcomes.
Spending more time in nature, or living in areas with more ambient greenspace, has been associated with increased positive affect in proportion to how highly participants rate their natural environment (Meidenbauer et al., 2020). Interestingly, children do not show the same initial preference for natural as opposed to urban environments that adults do, but the preference for nature increases with age (Meidenbauer et al., 2019). Despite this lack of explicit preference, there are still positive benefits for children who spend more time outdoors, not least of which due to increased physical activity. These benefits include improved cognitive function, mental health, sleep quality, and cardiovascular activity (Jiminez et al., 2021).
Meidenbauer has also found that children respond with neural responses of empathetic concern when seeing images of nature destroyed (Sahni et al., 2022), and upcoming lines of research will study how increased nature exposure might reduce aggression, counteracting the effects of heat stress.
Our environment matters, not just in shaping brain development from an early age, but in shaping our moods from day to day and season to season. Next time you get angry this summer, take a step back to cool off—both figuratively, and literally.
References
Anderson, C. A., Deuser, W. E., & DeNeve, K. M. (1995). Hot Temperatures, Hostile Affect, Hostile Cognition, and Arousal: Tests of a General Model of Affective Aggression. Personality and Social Psychology Bulletin, 21(5), 434–448. https://doi.org/10.1177/0146167295215002
Anderson, C. A. (2001). Heat and violence. Current Directions in Psychological Science, 10(1), 33-38.
Baron, R. A. (1972). Aggression as a function of ambient temperature and prior anger arousal. Journal of Personality and Social Psychology, 21(2), 183–189. https://doi.org/10.1037/h0032892
Baron, R. A., & Bell, P. A. (1976). Aggression and heat: The influence of ambient temperature, negative affect, and a cooling drink on physical aggression. Journal of Personality and Social Psychology, 33(3), 245–255. https://doi.org/10.1037/0022-3514.33.3.245
Cedeño Laurent, J. G., Williams, A., Oulhote, Y., Zanobetti, A., Allen, J. G., & Spengler, J. D. (2018). Reduced cognitive function during a heat wave among residents of non-air-conditioned buildings: An observational study of young adults in the summer of 2016. PLoS medicine, 15(7), e1002605. https://doi.org/10.1371/journal.pmed.1002605
Gronlund, C. J. (2014). Racial and socioeconomic disparities in heat-related health effects and their mechanisms: a review. Current Epidemiology Reports, 1(3), 165-173.
Jimenez, M. P., DeVille, N. V., Elliott, E. G., Schiff, J. E., Wilt, G. E., Hart, J. E., & James, P. (2021). Associations between nature exposure and health: a review of the evidence. International Journal of Environmental Research and Public Health, 18(9), 4790.
Keller, M. C., Fredrickson, B. L., Ybarra, O., Côté, S., Johnson, K., Mikels, J., Conway, A., & Wager, T. (2005). A warm heart and a clear head. The contingent effects of weather on mood and cognition. Psychological science, 16(9), 724–731. https://doi.org/10.1111/j.1467-9280.2005.01602.x
Meidenbauer, K. L., Stenfors, C., Young, J., Layden, E. A., Schertz, K. E., Kardan, O., Decety, J., & Berman, M. G. (2019). The gradual development of the preference for natural environments. Journal of Environmental Psychology, 65. doi: 10.1016/j.jenvp.2019.101328
Meidenbauer, K. L., Stenfors, C. U. D., Bratman, G. N., Gross, J. J., Schertz, K. E., Choe, K. W., & Berman, M. G. (2020) The affective benefits of nature exposure: What’s nature got to do with it? Journal of Environmental Psychology, 72: 101498. doi: 10.1016/j.jenvp.2020.101498
Piquero, A. R., Jennings, W. G., Jemison, E., Kaukinen, C., & Knaul, F. M. (2021). Domestic violence during the COVID-19 pandemic-Evidence from a systematic review and meta-analysis. Journal of Criminal Justice, 74, 101806.
Sahni, P.S., Rajyaguru, C., Narain, K., Meidenbauer, K. L., Jyoti, K., Schonert-Reichl, K. A. (2022, June 17). Neural Dynamics of Nature Empathy in Children: An EEG/ERP study. (PsyArXiv preprint). https://psyarxiv.com/c3hrm/
