Or so i’m going to claim because science is basically about making up whatever qualitative opinion you like and hard-selling it to a high impact journal right? Last night a paper appeared in PNAS early access entitled “Nature experience reduces rumination and subgenual prefrontal cortex activation” as a contributed submission. Like many of you I immediately felt my neurocringe brain area explode with activity as I began to smell the sickly sweet scent of gimmickry. Now I don’t have a lot of time so I was worried I wouldn’t be able to cover this paper in any detail. But never to worry, because the entire paper is literally two ANOVAs!
The paper begins with a lofty appeal to our naturalistic sensibilities; we’re increasingly living in urban areas, this trend is associated with poor mental health outcomes, and by golly-gee, shouldn’t we have a look at the brain to figure this all out? The authors set about testing their hypothesis by sending 19 people out into the remote wilderness of the Stanford University campus, or an urban setting:
The nature walk took place in a greenspace near Stanford University spanning an area ∼60 m northwest of Junipero Serra Boulevard and extending away from the street in a 5.3-km loop, including a significant stretch that is far (>1 km) from the sounds and sights of the surrounding residential area. As one proxy for urbanicity, we measured the proportion of impervious surface (e.g., asphalt, buildings, sidewalks) within 50 m of the center of the walking path (Fig. S4). Ten percent of the area within 50 m of the center of the path comprised of impervious surface (primarily of the asphalt path). Cumulative elevation gain of this walk was 155 m. The natural environment of the greenspace comprises open California grassland with scattered oaks and native shrubs, abundant birds, and occasional mammals (ground squirrels and deer). Views include neighboring, scenic hills, and distant views of the San Francisco Bay, and the southern portion of the Bay Area (including Palo Alto and Mountain View to the south, and Menlo Park and Atherton to the north). No automobiles, bicycles, or dogs are permitted on the path through the greenspace.
Wow, where can I sign up for this truly Kerouac-inspired bliss? The control group on the other hand had to survive the horrors of the palo-alto urban wasteland:
The urban walk took place on the busiest thoroughfare in nearby Palo Alto (El Camino Real), a street with three to four lanes in each direction and a steady stream of traffic. Participants were instructed to walk down one side of the street in a southeasterly direction for 2.65 km, before turning around at a specific point marked on a map. This spot was chosen as the midpoint of the walk for the urban walk to match the nature walk with respect to total distance and exercise. Participants were instructed to cross the street at a pedestrian crosswalk/stoplight, and return on the other side of the street (to simulate the loop component of the nature walk and greatly reduce repeated encounters with the same environmental stimuli on the return portion of the walk), for a total distance of 5.3 km; 76% of the area within 50mof the center of this section of El Camino was comprised of impervious surfaces (of roads and buildings) (Fig. S4). Cumulative elevation gain of this walk was 4 m. This stretch of road consists of a significant amount of noise from passing cars. Buildings are almost entirely single- to double-story units, primarily businesses (fast food establishments, cell phone stores, motels, etc.). Participants were instructed to remain on the sidewalk bordering the busy street and not to enter any buildings. Although this was the most urban area we could select for a walk that was a similar distance from the MRI facility as the nature walk, scattered trees were present on both sides of El Camino Real. Thus, our effects may represent a conservative estimate of effects of nature experience, as our urban group’s experience was not devoid of natural elements.
And they got that approved by the local ethics board? The horror!
The authors gave both groups a self-reported rumination questionnaire before and after the walk, and also acquired some arterial spin labeling MRIs. Here is where the real fun gets started – and basically ends – as the paper is almost entirely comprised of group by time ANOVAs on these two measures. I wish I could say I was suprised by what I found in the results:
That’s right folks – the key behavioral interaction of the paper – is non-significant. Measly. Minuscule. Forget about p-values for a second and consider the gall it takes to not only completely skim over this fact (nowhere in the paper is it mentioned) and head right to the delicious t-tests, but to egregiously promote this ‘finding’ in the title, abstract, and discussion as showing evidence for an effect of nature on rumination! Erroneous interaction for the win, at least with PNAS contributed submissions right?! The authors also analyzed the brain data in the same way – this time actually sticking with their NHST – and find that some brain area that has been previously related to some bad stuff showed reduced activity. And that – besides a heart rate and respiration control analyses – is it. No correlations with the (non-significant) behavior. Just pure and simple reverse inference piled on top of fallacious interpretation of a non-significant interaction. Never-mind the wonky and poorly operationalized research question!
See folks, high impact science is easy! Just have friends in the National Academy…
I’ll leave you with this gem from the methods:
“‘One participant was eliminated in analysis of self-reported rumination due to a decrease in rumination after nature experience that was 3 SDs below the mean.'”
That dude REALLY got his time’s worth from the walk. Or did the researchers maybe forget to check if anyone smoked a joint during their nature walk?