Fractions present a unique challenge in early mathematics instruction, as they require focusing not on the individual symbols that make up the fraction, but rather a mental combination of the two into a single numerical magnitude. Previous studies have given conflicting accounts of how adults form these complex mental representations. Whereas some studies indicate that mental representations of fractions are holistic and are based upon the fraction’s numerical magnitude, others have indicated support for decomposed processing, where separate representations of the numerator and denominator are formed. In the present study, we tested this decomposed processing account using an implicit priming paradigm. In a series of experimental trials, the comparison of two fraction magnitudes (“which is larger?”) primed a subsequent comparison trial with whole numbers. Using Bayesian analyses, we found that when people compared two fractions with common denominators, they were faster in the subsequent whole number comparison. However, when two fractions with common numerators were compared, the subsequent whole number comparison was slower. This indicates that representations of the fraction components were activated in the fraction comparison, and these residual activations primed the subsequent whole number comparison. These data give further support to the notion of decomposed processing in fraction comparison.
Evidence for a visuospatial bias in decimal number comparison in adolescents and in adults
