Using addition to solve large subtractions in the number domain up to 20.
This study examined 25 university students' use of addition to solve large single-digit subtractions by contrasting performance in the standard subtraction format (12-9=.) and in the addition format (9+.=12). In particular, we investigated the effect of the relative size of the subtrahend on performance in both formats. We found a significant interaction between format, the magnitude of the subtrahend (S) compared to the difference (D) (S>D vs. S<D), and the numerical distance between subtrahend and difference. When the subtrahend was larger than the difference and S and D were far from each other (e.g., 12-9=.), problems were solved faster in the addition than in the subtraction format; when the subtrahend was smaller than the difference and S and D were far from each other (e.g., 12-3=.), problems were solved faster in the subtraction than in the addition format. However, when the subtrahend and the difference were close to each other (e.g., 13-7=.), there were no significant reaction time differences between both formats. These results suggest that adults do not rely exclusively and routinely on addition to solve large single-digit subtractions, but select either addition-based or subtraction-based strategies depending on the relative size of the subtrahend.
Peters
Greet
G
Centre for Instructional Psychology and Technology, Katholieke Universiteit Leuven, Belgium. Greet.Peters@ped.kuleuven.be
De Smedt
Bert
B
Torbeyns
Joke
J
Ghesquière
Pol
P
Verschaffel
Lieven
L
D000328:Adult; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D011340:Problem Solving; D011930:Reaction Time; D013647:Task Performance and Analysis; D055815:Young Adult