AUTHOR=Shaki Samuel , Fischer Martin H. 

TITLE=Competing Biases in Mental Arithmetic: When Division Is More and Multiplication Is Less

JOURNAL=Frontiers in Human Neuroscience

VOLUME=11

YEAR=2017

URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2017.00037

DOI=10.3389/fnhum.2017.00037

ISSN=1662-5161

ABSTRACT=<p>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 <underline>over-</underline>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.</p>