As a society slowly urbanizes over time, its psychology and culture change, too... If American culture and psychology grew more individualistic as the country urbanized, wouldn't that transformation be clear in the words from American books (and the concepts that lie behind them)? — The Atlantic Cities
Urban and rural environments impact personal psychology differently, according to research published by UCLA psychologist Patricia Greenfield in Psychological Science. While observational evidence may draw a clear line between current city- and country-mindsets, Greenfield's source material draws on data from over 200 years of publishing in the United States. Using Google Books Ngram Viewer, Greenfield tracked English words that refer to certain trends or larger ideas, such as "obliged" vs. "choose", to see if urbanization accompanies a more individualistic mentality. It's given that a word's frequency of use will change over time, but seeing how that frequency correlates with urbanization is an exciting metric for the collective urban unconscious.