All of those saying correlation is not causation did not read the article. The study detected an immediate and neasurable effect from just walking among trees.
I was the parent of the thread that brought up 'correlation is not causation' point [0]. I did read the entire article, as well as other papers on the effects of environment on well being.
My main point however, is a call for some prudence especially with the relatively recent focus on bad statistics in psychology and the neurosciences. A caution against accepting a paper's conclusions because of the correlation of a few variables, and the omission of some obvious other ones. Here's just one link from 2013 [1]. fMRIs are a tool, and like any other, can be used incorrectly, which is also part of the problem. I am not negating Marc Berman's paper or this article based on it; I am just a bit wary of papers or articles with big claims (remember the article cites a 1% improvement after all of the buoying of the affects).
A variable not mentioned is that if you are walking outside, or facing a bunch of trees in a yard from your hospital room, you are getting daylight. Window panes block UVb, but not UVa (some are treated to block UVa too). Sunlight/daylight help you to produce vitamin D, which is linked to depression and the immunity system. This could be the cause of the 1% improvement the article states, and possibly not the trees.
Treatment for clinical depression figures are 60-80% successful depending on the study. An order of magnitude greater than 1% [2].
Aside from the few people who have replied to this thread about allergies and other maladies, how many people do you think are going to associate pain, depression or other negatives with an image of trees in their head when responding to a survey?
All that being said. My neighborhood was poor, and crime-ridden, yet my tree-lined block provided me with many peaceful moments of just staring at the trees, or simply listening to the wind in the leaves. I do believe they are beneficial, at least to me (except during a hurricane in NJ, where I thought the 60 foot tall, old oak tree just by my house was going to fall on my roof!).
It's worth noting that the original publication doesn't claim that it is the trees that have the effect. That is a layer of confusion generated by the New Yorker author. Berman's original work compares "natural" vs urban environments.
Now I think this probably is causation, but pointing out that the correlation is really strong is not an argument against "correlation is not causation".
Reflexively trotting out "correlation is not causation" is a thought terminating cliche. It short circuits our thinking. People often stop at the statement, feeling satisfied in their scientific abilities.
My main point however, is a call for some prudence especially with the relatively recent focus on bad statistics in psychology and the neurosciences. A caution against accepting a paper's conclusions because of the correlation of a few variables, and the omission of some obvious other ones. Here's just one link from 2013 [1]. fMRIs are a tool, and like any other, can be used incorrectly, which is also part of the problem. I am not negating Marc Berman's paper or this article based on it; I am just a bit wary of papers or articles with big claims (remember the article cites a 1% improvement after all of the buoying of the affects).
A variable not mentioned is that if you are walking outside, or facing a bunch of trees in a yard from your hospital room, you are getting daylight. Window panes block UVb, but not UVa (some are treated to block UVa too). Sunlight/daylight help you to produce vitamin D, which is linked to depression and the immunity system. This could be the cause of the 1% improvement the article states, and possibly not the trees. Treatment for clinical depression figures are 60-80% successful depending on the study. An order of magnitude greater than 1% [2].
Aside from the few people who have replied to this thread about allergies and other maladies, how many people do you think are going to associate pain, depression or other negatives with an image of trees in their head when responding to a survey?
All that being said. My neighborhood was poor, and crime-ridden, yet my tree-lined block provided me with many peaceful moments of just staring at the trees, or simply listening to the wind in the leaves. I do believe they are beneficial, at least to me (except during a hurricane in NJ, where I thought the 60 foot tall, old oak tree just by my house was going to fall on my roof!).
[0] https://en.wikipedia.org/wiki/Correlation_does_not_imply_cau...
[1] http://www.wired.com/2013/04/brain-stats/
[2] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908269/