Paper Bullets: Modeling Propaganda with the Help of Metaphor

Findings of the Association for Computational Linguistics: EACL 2023, pages 472–489 May 2-6, 2023 ©2023 Association for Computational Linguistics Paper Bullets: Modeling Propaganda with the Help of Metaphor Daniel Baleato Rodríguez ILLC, University of Amsterdam daniel@codealia.com Verna Dankers ILCC, University of Edinburgh vernadankers@gmail.com Preslav Nakov MBZUAI preslav.nakov@mbzuai.ac.ae Ekaterina Shutova ILLC, University of Amsterdam e.shutova@uva.nl Abstract Propaganda aims to persuade an audience by appealing to emotions and using faulty reason- ing, with the purpose of promoting a particular point of view. Similarly, metaphor modifies the semantic frame, thus eliciting a response that can be used to tune up or down the emotional volume of the message. Given the close rela- tionship between them, we hypothesize that, when modeling them computationally, it can be beneficial to do so jointly. In particular, we perform multi-task learning with propaganda identification as the main task and metaphor de- tection as an auxiliary task. To the best of our knowledge, this is the first work that models metaphor and propaganda together. We exper- iment with two datasets for identifying propa- ganda techniques in news articles and in memes shared on social media. We find that leveraging metaphor improves model performance, partic- ularly for the two most common propaganda techniques: loaded language and name-calling. 1 Introduction Propaganda aims to influence an audience. It is a type of information that, whether true or false, tries to promote a particular agenda (Cantril, 1938) by appealing to emotions or by using faulty reason- ing (Miller, 1939). Although this communication strategy comes in many forms, it is conveyed us- ing specific persuasion techniques that exploit our psychology to sell us an idea or a point of view (Da San Martino et al., 2019b). In Figure 1, we can see an example of such techniques used in a meme shared on social media. Another rhetorical device at the heart of many successful communication strategies is metaphor. Postulated as a primordial mechanism to conceptu- alize what we think and experience (Lakoff, 1980), metaphor works by mapping a concept in one do- main (often a physical domain) to another domain (usually an abstract one) by means of a systematic Figure 1: Meme containing propagandistic techniques (Dimitrov et al., 2021). These techniques are high- lighted with bounding boxes for illustration purposes. association. For instance, the term “paper bullets”1 connects the domains of information and war, illus- trating the weaponization of information. In the same way that propaganda can exploit automatic shortcuts our brain uses to process infor- mation (e.g., stereotypes) (Tversky and Kahneman, 1974), metaphors can affect how we reason about a particular situation or issue by evoking a different semantic frame (Fillmore et al., 2006). Research shows that characterizing crime as a beast deliv- ered more punishment-oriented strategies to fight crime (Thibodeau and Boroditsky, 2011). Con- 1The metaphor “paper bullets” was used during World War II, where the Germans used tactical aircrafts to drop anti- Semitic leaflets over American troops (Margolin, 1946) as a way of psychological warfare. 472 versely, referring to crime as …

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