title: Competing Biases in Mental Arithmetic: When Division Is More and Multiplication Is Less.
abstract: Mental arithmetic exhibits various biases. Among those is a tendency to overestimate addition and to underestimate subtraction outcomes. Does such "operational momentum" (OM) also affect multiplication and division? Twenty-six adults produced lines whose lengths corresponded to the correct outcomes of multiplication and division problems shown in symbolic format. We found a reliable tendency to over-estimate division outcomes, i.e., reverse OM. We suggest that anchoring on the first operand (a tendency to use this number as a reference for further quantitative reasoning) contributes to cognitive biases in mental arithmetic.
authors.affiliation: Department of Behavioral Sciences, Ariel University Ariel, Israel.
authors.forename: Samuel
authors.initials: S
authors.lastname: Shaki
authors.affiliation: Division of Cognitive Science, University of Potsdam Potsdam, Germany.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Fischer
keywords: heuristics and biases; mental arithmetic; mental number line; numerical cognition; operational momentum