A Measurement Framework for Computationally Analyzing Politicians' Body Language

Politicians can increase the appeal of their speeches through nonverbal cues such as gestures and vocal emphasis. Understanding the factors that make political speech appealing is central to political science research, but studying nonverbal cues during political speech is difficult due to their audiovisual nature. This article proposes an intuitive and widely applicable framework for measuring nonverbal cues, particularly body language, based on video recordings of political speech. I showcase the approach's utility by studying the relationship between politicians' nonverbal appeals and the textual complexity of more than 30,000 parliamentary speeches in the German Bundestag (2011--2020). The results point towards a trade-off between verbal and nonverbal elements of political speeches: Efforts to deliver a nonverbally appealing speech often come at the cost of textual complexity, while textual complexity tends to diminish nonverbal effort. Legislators of governing parties navigate this trade-off by leaning towards complexity over nonverbal appeal, while opposition members tend to choose nonverbal appeal over complexity.