Proceedings of the Annual Meeting of the Cognitive Science Society

We quantitatively modeled and compared two types of errorsin numerical estimation for naturalistic judgment targets: map-ping errors and knowledge errors. Mapping errors occur whenpeople make mistakes reporting their beliefs about a particularnumerical quantity (e.g. by inflating small numbers), whereasknowledge errors occur when people make mistakes usingtheir knowledge about the judgment target to form their be-liefs (e.g. by overweighting or underweighting cues). In twostudies, involving estimates of the calories of common fooditems and estimates of infant mortality rates in various coun-tries, we found that knowledge error models predicted partic-ipant estimates with very high out-of-sample accuracy rates,significantly outperforming the predictions of mapping errormodels. The knowledge error models were also able to iden-tify the objects and concepts most associated with incorrectestimates, shedding light on the psychological underpinningsof numerical judgment.