Perceived Source Variability Versus Familiarity: Testing Competing Explanations for the Truth Effect

This article tests 2 competing explanations for the truth effect, the finding that repeated statements are believed more than new statements. Previous research has put forth 2 explanations for this effect—subjective familiarity and perceived source variability. The subjective familiarity explanation holds that repeated statements feel more familiar and are therefore believed more than new statements. This explanation has received strong support in the literature. The source variability explanation holds that people attribute repeated statements to different sources; this belief, that multiple sources endorse the statement, increases belief in repeated statements relative to new statements attributed to a single source. However, previous studies testing this explanation have confounded source variability with source credibility. This research aims to tease apart the effects of subjective familiarity and source variability while holding source credibility constant across conditions. Results of the first 2 experiments manipulating number of sources and measuring recognition implicate subjective familiarity rather than perceived source variability as the mechanism underlying the truth effect. However, the third study demonstrates that source variability does enhance belief in repeated statements that are initially perceived as low in plausibility. Theoretical and practical implications are discussed.