Erratum for the Research Article "How do social media feed algorithms affect attitudes and behavior in an election campaign?".

This erratum addresses the treatment of Instagram "carousel" versus "non-carousel" posts in the 2020 Facebook-Instagram Election Study (FIES) analyzed in the original research article on social media feed algorithms and election campaign effects. Carousel posts, which contain multiple photos or videos users can swipe through, were not consistently distinguished from single-item posts in the original metrics, affecting how exposures, engagements, and content classifications were counted. The authors clarify that this inconsistency did not impact experimental effect estimates related to Instagram or other platforms but likely led to underestimation of certain content types, such as uncivil posts. Due to privacy-related data delinking, the authors cannot reanalyze the data with consistent treatment of carousel posts but provide updated metric definitions and supplementary materials to reflect their revised understanding. [Extracted from the article]