Spoken numbers versus Arabic numerals: differential effects on adults' multiplication and addition

J.-A. LeFevre, Q. Lei, B. L. Smith-Chant, and D. B. Mullins (2001) examined effects of auditory versus Arabic visual presentation formats on performance of simple multiplication. They observed a smaller problem-size effect (response time [RT] increases with numerical size) with auditory stimuli compared with Arabic stimuli. If this arises during problem encoding, as opposed to during subsequent calculation processes, the authors would expect comparable Format x Problem Size interactions for both multiplication and addition. For multiplication, the authors replicated the finding of a smaller problem-size effect for auditory stimuli than for Arabic stimuli, but found the opposite pattern for addition whereby the problem-size effect was larger with auditory stimuli than with Arabic stimuli. Decomposition of mean RT into its ex-Gaussian components, mu and tau, demonstrated that the triple interaction arose entirely in connection with tau. This suggests that the effects of auditory versus Arabic format on RT substantially reflected format-related shifts in the use of procedural strategies.