Ending up with less: the role of working memory in solving simple subtraction problems with positive and negative answers

Abstract

Does solving subtraction problems with negative answers (e.g., 5–14) require different cognitive processes than solving problems with positive answers (e.g., 14–5)? In a dual-task experiment, young adults (N=39) combined subtraction with two working memory tasks, verbal memory and visual-spatial memory. All of the subtraction problems required verbal working memory but only large problems with negative answers (e.g., 8–17) required visual-spatial working memory. Small-operand problems (e.g., 5–3) required less verbal working memory than large-operand problems (e.g., 15–9). Answers to small problems were probably retrieved from memory even when the answer was negative (e.g., 3–5). In contrast, large problems with negative answers may have required participants to modify their solution procedures such that problem difficulty increased. These results indicate that even relatively simple subtraction problems can be cognitively demanding of both verbal and visual-spatial working memory, especially when solutions are not activated automatically.

Keywords:

• subtraction
• dual-task method
• negative numbers

Acknowledgements

Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada through a postgraduate scholarship to Nicole D. Robert and a Discovery Grant to Jo-Anne LeFevre. We thank Kristina Dunbar for her assistance collecting data and preparing the manuscript.