Online Misinformation Harms on Social Media during Crises: Misinformation Harm Types, Perceptions, Antecedents, and Effects toward Misinformation Sharing

During humanitarian crises like natural disasters, manmade crises, health crises or several complex crises, people are motivated to seek for a large amount of information in a limited time to make proper important decisions. Social media platforms can support quick crisis communication but can also be subject to harmful misinformation or false claims. To contribute to efforts facing harms from crisis misinformation, this dissertation includes three essays that investigates different aspects of misinformation harms such as different types or dimensions of harms and causalities surrounding the harms. The first essay draws insights from previous related studies about the harms of consuming information to develop a taxonomy of both short-term and long-term crisis misinformation harms, including 15 types of harms grouped in 8 categories such as physical or psychological harms. Such taxonomy was then validated in two misinformation scenarios related to healthcare crisis and natural disaster, and through a post hoc analysis of different groups of participants. The second essay develops a mechanism to quantify health crisis misinformation harms from 6 COVID-19 pandemic misinformation scenarios. The mechanism addresses perceptions of crisis misinformation harms captured by a survey in two categories of harms, comparative harms (including component harms and contextual harms based on specific contexts) and noncomparative harms (counter-contextual harms based on counterfactual comparisons of different contexts), with significant differences between the pandemic victims and nonvictims. Concerning about 10 COVID-19 vaccine misinformation, the third essay includes two rounds of a longitudinal survey investigates the causality surrounding misinformation harms with certain antecedents (like trust and science attitudes) and the effects on misinformation sharing decisions. In summary, the dissertation aims to examine the under-addressed phenomenon of crisis misinformation harms, to contribute to the literature of crisis communication, to support efforts confronting misinformation diffusions, and to help optimize emergency responses related to misinformation harms.