**Interests**

**The role of language in numerical cognition**

How do people process numbers in inverted number languages (e.g., Dutch: vierenvijftig)?
And are there any differences with number processing in non-inverted number languages (e.g., English: fifty-four)?
What is the role of working memory in children's number transcoding?
And does this role differ between Dutch- and French-speaking children?
**Cultural differences in arithmetic performance**

Why are Chinese people faster in solving arithmetic problems than are European and North-American people?
Do Asian, European, and North-American people choose other strategies to solve arithmetic problems?
Do Asian, European, and North-American people use other working-memory components to solve arithmetic problems?
Is it true that Asian-educated people choose their strategies less adaptively than do non-Asian-educated people?
**The role of working memory in mental arithmetic**

What is the role of working memory in complex forms of mental arithmetic,e.g., in carry and borrow operations?
What is the role of working memory in simple-arithmetic strategy efficiency (e.g., 5 + 7, 3 x 8)?
What is the role of working memory in complex-arithemtic strategy efficiency (e.g., 53 + 78, 3 x 18)?
Do working-memory components play a role in strategy selection and strategy efficiency?
Do we need more working-memory resources for exact calculation than for approximate calculation?
**The selection and the efficiency of arithmetical strategies**

What are the effects of training and practice on arithmetic strategy selection and strategy efficiency?
How do strategy selection and strategy efficiency develop across elementary school?
What is the role of working memory in strategy efficiency, strategy selection, and strategy adaptivity?
Do individual differences (e.g., math anxiety, gender) have an influence on selection and/or efficiency processes?
**The role of structure in the development of visuo-spatial working memory**

Does structural information influence the development of visuo-spatial working-memory performance?
Can the effect of structure be attributed to other path characteristics such as the path length or the number of path crossings?
**Synesthesia**

Is synesthesia uni- or bi-directional?
What are the effects of grapheme-color synesthesia on simple-arithmetic performance?
**Post-error slowing**

Why do we slow down after an error? Why is there no gain in accuracy?
Is post-error slowing also present in mental arithmetic?
**The development of the SNARC effect**

How does the SNARC effect develop in elementary school children?
Does left-right knowledge affect this developmental process?
**The role of working memory in a variety of cognitive tasks**

What is the role of working memory in object recognition? (project Yun Zheng)
Which working-memory components do we need to drive a car? (project Kamilla Johannsdottir)