Strategy choice for arithmetic verification: effects of numerical surface form

Canadian university students (n = 48) solved simple addition problems in a true/false verification task with equations in digit format (3 + 4 = 8) or written English format (three + four = eight). Participants reported their solution strategy (e.g. retrieval or calculation) after each trial. Reported use of calculation strategies was much greater with word (41%) than digit stimuli (26%), and this difference was exaggerated for numerically larger problems. Word-format costs on reaction time (RT) were correspondingly greater for large than for small problems, but this Format X Size RT effect was bigger for true than for false equations. The results demonstrate that surface format affects central, rather than only peripheral, stages of cognitive arithmetic. (C) 2001 Elsevier Science B.V. All rights reserved.