A signal detection analysis of source effects on misinformation susceptibility

Signal Detection Theory suggests that people may fall for misinformation because they are unable to discern true from false information (i.e., low truth sensitivity) or because they have a general tendency to accept information regardless of veracity (i.e., low acceptance threshold). While a large body of evidence suggests that characteristics of information sources can influence susceptibility to misinformation, it remains unclear how source characteristics affect misinformation susceptibility. Using a signal-detection approach, the current research investigated (1) whether source characteristics influence truth judgments of true and false information via truth sensitivity or acceptance thresholds; (2) potential differences between perceived reliability and perceived partisanship as distinct facets of sources; and (3) how the two facets interact with information content in shaping judgments of true and false information. Across seven preregistered experiments ( N = 4,286), we found that (1) source characteristics affected susceptibility to misinformation via acceptance thresholds, not truth sensitivity per se; (2) effects of source characteristics were limited to conditions where comparisons of sources are salient; (3) source characteristics had no effect on partisan bias, in that acceptance thresholds were substantially lower for ideology-congruent than ideology-incongruent information regardless of the source; and (4) perceived reliability and perceived partisanship showed corresponding effects on acceptance thresholds regardless of information content, suggesting that both source characteristics might influence truth judgments via perceived source credibility. Together, the findings provide deeper insights into how source characteristics influence susceptibility to misinformation.