Abstract

Estimates of unknown quantities are influenced by both self-generated anchors (SGAs) and externally provided anchors (EPAs; e.g., the advice of others). It was hypothesised that people use the degree of similarity between these anchors to render final responses. Thus we tested predictions drawn from metacognitive accounts of anchoring using procedures similar to the traditional anchoring paradigm. In a single experiment we manipulated SGA–EPA similarity, EPA level, and EPA source credibility. Results showed that the relationship between SGA–EPA similarity and the decision weight given to the EPA, relative to the weight given to the SGA, depended on source credibility. Bolstering the metacognitive framework, participants were most confident about their final responses when their SGA was similar to the EPA and the EPA came from a highly credible source. These results support a metacognitive account of the anchoring heuristic.