The data is quite interesting, but the hypothesis (imo) is far from the only plausible explanation. I'm not saying this to disparage the work, just to frame. "

The data is quite interesting, but the hypothesis (imo) is far from the only plausible explanation. I'm not saying this to disparage the work, just to frame. "Individuals with depression are prone to maladaptive patterns of thinking, known as cognitive distortions, whereby they think about themselves, the world, and the future in overly negative and inaccurate ways. These distortions are associated with marked changes in an individual’s mood, behavior, and language. We hypothesize that societies can undergo similar changes in their collective psychology that are reflected in historical records of language use. Here, we investigate the prevalence of textual markers of cognitive distortions in over 14 million books..." Interesting result: https://www.pnas.org/content/pnas/118/30/e2102061118/F4.large.jpg https://www.pnas.org/content/pnas/118/30/e2102061118/F4.larg... So... the finding is that language patterns typically associated with depression have rapidly become common in book language. Interesting. The interpretation is up for debate, I suppose. Maybe its just writers are more depressed. Financial events are labeled, but they don't seem to have impacted the data much. Internet usage, OTOH, seems (at a glance) highly correlated to whatever they're measuring. Maybe online culture moved language in this direction with no real relationship to depression. Maybe the internet made people more depressed. Maybe the internet made writers more depressed. Maybe some complicated knot of those. IE, the internet popularized maladaptive language, which has made us all more depressed. In any case, assuming the methodology is reasonable, it does look like they've found something here. Worth a discussion.