Linguistic positivity in historical texts reflects dynamic environmental and psychological factors

Abstract

People use more positive words than negative words. Referred to as "linguistic positivity bias" (LPB), this effect has been found across cultures and languages, prompting the conclusion that it is a panhuman tendency. However, although multiple competing explanations of LPB have been proposed, there is still no consensus on what mechanism(s) generate LPB or even on whether it is driven primarily by universal cognitive features or by environmental factors. In this work we propose that LPB has remained unresolved because previous research has neglected an essential dimension of language: time. In four studies conducted with two independent, time-stamped text corpora (Google books Ngrams and the New York Times), we found that LPB in American English has decreased during the last two centuries. We also observed dynamic fluctuations in LPB that were predicted by changes in objective environment, i.e., war and economic hardships, and by changes in national subjective happiness. In addition to providing evidence that LPB is a dynamic phenomenon, these results suggest that cognitive mechanisms alone cannot account for the observed dynamic fluctuations in LPB. At the least, LPB likely arises from multiple interacting mechanisms involving subjective, objective, and societal factors. In addition to having theoretical significance, our results demonstrate the value of newly available data sources in addressing long-standing scientific questions.Pollyanna hypothesis | positivity in language | automated text analysis | subjective happiness F or a naive observer, human language use often appears to be a function of utility and context. We craft our enunciations according to our intentions and, aside from correlations between language and environmental and experiential cues, we seem to be masters of our words. However, as social scientists have long recognized, linguistic patterns are also a function of social, cultural, and cognitive factors (1-5).One of the more striking examples of such linkages comes from research on the affective content of language revealing that people use positive words more frequently than negative words, an effect first reported by Zajonc in 1968 (6) and subsequently replicated many times (7-11). This phenomenon, initially referred to as the "Pollyanna hypothesis" (7) and more recently as "linguistic positivity bias" (LPB) (9), has been demonstrated across numerous languages and corpora (7,11,12), leading to the conclusion that it is a panhuman tendency.However, although the existence of LPB is well-established, there is surprisingly little consensus on what mechanisms are responsible for the effect. Among the mechanisms proposed are universal cognitive biases (6, 7), affective states (12), objective circumstances (8), and societal norms (9, 10, 12). However, research has been unable to establish which of these mechanisms drives LPB and whether the effect might be driven by interaction between a subset of these or other factors. One reason for this uncertainty is that previous investigations of LPB ha...

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