# My PhD

**Title**: Strategy selection and strategy efficiency in mental arithmetic

**Promotor**: Prof. dr. André Vandierendonck

**Defense**: 15 March 2007

**Description**

Intro -- People use lots of strategies to solve simple-arithmetic problems. Examples are direct memory retrieval (i.e., ‘knowing’ that 6 x 7 = 42), counting (e.g., 4 x 8 = 8 - 16 - 24 - 32) and transformation (e.g., 9 x 5 = (10 x 5) – 5). Choosing among several strategies refers to strategy selection. The speed and the accuracy with which strategies are executed, refers to strategy efficiency. In this PhD project, several unresolved issues concerning simple-arithmetic strategies will be investigated.

Part 1 -- Little is known about the effects of training and practice on simple-arithmetic strategy selection and strategy efficiency. Present PhD project uses two different approaches to test training/practice effects. First, a rather ‘ecological’ approach is used, in which we test secondary-school students with different amounts of daily arithmetical practice. Second, a more experimental approach is used, in which we explicitly train participants to solve simple-arithmetic problems.

Part 2 -- Although lots of studies showed that working memory plays an important role in simple arithmetic, little is known about the role of working memory across different strategies. To this end, we investigate the role of the phonological loop and the central executive in the execution of several simple-arithmetic strategies. Moreover, we also test whether strategy selection is affected by working-memory load. The role of working memory in strategy selection and strategy efficiency is examined by means of the choice/no-choice method for all basic operations (i.e., addition, subtraction, multiplication, and division).

Part 3 -- It is clear that children’s performance on simple-arithmetic problems increases with age. In this PhD project, we further investigate the development of strategy selection and strategy efficiency in elementary-school children. The problem-size effect and differences across operations will be examined thoroughly. We also test the role of the central executive in children’s strategy selection and strategy efficiency across development.