Long-Term Resistance Against Persuasion: Unveiling Decay and Extending Inoculation Theory

In an age where our beliefs and attitudes are continuously challenged, studying the psychology of persuasion is particularly relevant. To protect society against the negative consequences of misinformation, it is not only important to learn how to tackle misinformation, it is also of crucial importance to understand how to prevent being influenced by misinformation. We thus need to understand the psychological mechanisms behind resistance against persuasion. While strong theoretical frameworks of resistance against persuasion have been proposed in the past decades, there is a large lack of understanding of the decay of resistance over time. The purpose of this PhD is to fill this gap in scientific research on long-term resistance against persuasion , a gap that is present in multiple facets of persuasion theory.
"Decay of the effects of political persuasion is too important to be ignored, as it routinely has been. It is a basic feature of mass persuasion in most if not all political contexts. Scholars should therefore try harder to build measurement of decay into their research designs." - Hill, Lo, Vavreck, & Zaller (2013)

My focus in this PhD project will be on a specific theory of resistance against persuasion, the inoculation theory (McGuire & Papageorgis, 1962) . Inoculation theory is often referred to as the master theory of resistance against persuasion (Eagly & Chaiken, 1993). It represents a biological metaphor where a person is exposed to a weakened version of an argument which is preemptively debunked (refuted before exposure to the full argument), which leads to the creation of mental
antibodies that confer resistance against persuasion. Inoculation research has been conducted since the early 60s, and according to a recent meta-analysis it has consistently proven to be effective in arming people against persuasion, more so than other techniques (Banas & Rains, 2010).

"Over the past 50 years, inoculation theory has emerged as the most consistent and reliable method for conferring resistance to persuasion." - Miller et al. (2013)

Inoculation is broadly used to benefit society. It is used in health campaigns, from smoking prevention to protection against influence from anti-vaccination misinformation. From climate change communication to more recently the battle against disinformation. Yet, there is no consensus or generally accepted view on the decay function of the inoculation effect (Banas & Rains, 2010). Gaining insights into the decay of resistance, I will significantly expand the inoculation theory,
making notable impact on fundamental science ( What are the mechanisms to acquire long-term cognitive resistance to persuasion? ), and have a broad influence on a multitude of applied domains (Ivanov, 2017) and therefore advance societal impact ( How do we maximise the long-time effectiveness of our inoculation based interventions? ).
"Researchers have documented that inoculation treatments decay, or lose their effectiveness over time. More research about the inoculation decay process is needed." - Banas & Rains (2010)

During the PhD, I will try to answer the following research questions: 1) What is the shape of the decay function of the inoculation effect? 2) Do different inoculation methods have differential long-term effectiveness? 3) Can booster shots prevent decay, and can we optimise long-term impact? 4) Are there other, non-method related influences on the decay function? To answer these questions, I will a) thoroughly map the inoculation decay function , b) compare different
methods of inoculation in their long-term effectiveness , c) explore the potential of booster shots to improve the decay function and d) analyse non-method-related differences in the decay function.