Remembering and forgetting information about the COVID-19 vaccine on Twitter.

Social media exposes people to selective information of what they have previously known. We conducted two laboratory studies to examine in a simulated online context the phenomenon of retrieval-induced forgetting, where information reposted on social media is likely to be later remembered and relevant but not reposted information may be forgotten. Specifically, we examined how exposure to selective information about the COVID-19 vaccine via tweets affected subsequent memory and whether people's attitudes towards vaccination played a role in their memory for the information. Young adults (N = 119; Study 1) and community members (N = 92; Study 2) were presented with information about the COVID-19 vaccine that included both pro- and anti-vaccine arguments, organised in four categories (i.e., science, children, religion, morality). They then read tweets that repeated half of the arguments from two of the categories. In a subsequent memory test, participants remembered best the statements repeated in the tweets and remembered worst the statements from the same category but not repeated in the tweets, thus exhibiting retrieval-induced forgetting. This pattern of results was similar across pro- and anti-vaccine arguments, regardless of the participants' level of support for vaccination. We discussed the findings in light of remembering and forgetting in the context of the pandemic and social media.