Different brain mechanisms mediate two strategies in arithmetic: evidence from Event-Related brain Potentials

Participants were asked to verify if complex additions were smaller than 100 or not. Two hundred and forty arithmetic problems were presented, with half the problems being small-split problems (i.e. proposed sums were 2 or 5% away from 100) and half being large-split problems (i.e. proposed sums were 10 or 15% away from 100). Behavioral and ERPs data indicate that participants may use two different strategies to verify complex inequalities, a whole-calculation strategy for small-split problems and an approximate-calculation strategy for large-split problems. The choice between these two strategies occurred within 250 ms post-stimulus presentation, and strategy execution was lateralized. Implications for our understanding of the brain mechanisms underlying arithmetic problem solving are discussed.