Evolution of U.S. Presidential Discourse over 230 Years: A Psycholinguistic Perspective

Much of recent research on U.S presidential discourse has focused on the nexus between language forms and their underlying social processes and psychological states. However, little work has been done to shed light on how these latent characteristics have evolved over time. This study investigated the evolution of three psychological states (authenticity, affect, and time orientation) underlying U.S. presidential discourse over approximately 230 years (1789-2016). Based on one of the most comprehensive corpora of presidential speech transcripts, Linguistic Inquiry and Word Count (LIWC) 2015, a text analysis software, was utilized to explore these psychological states. To see the overall trend of these states across U.S. presidential history as a whole, initial analysis was based on LIWC indices, which showed that, 1) overall, authenticity level is on a steady increase in U.S. presidential discourse; 2) in the presidents' speeches, positive emotions invariably outweigh negative emotions, and both types of emotion remain relatively constant in the long run; 3) the discourse of "focus on present" consistently outweighs the discourse of "focus on future", which outweighs the discourse of "focus on past". To see whether the general trend holds across different parties, a series of independent samples t-tests were first performed to check for significant difference. The results indicated that in all the three psychological states, there was no significant difference between the Democratic presidents and the Republican presidents, and that the trend in different parties is in agreement with the overall trend. Subsequent visualization of the LIWC indices according to party generally corroborated these results, with only one exception: authenticity levels are on a steady increase in the discourse of the Democratic presidents, but in the Republican presidents, there was a sharp increase in recent years.