The aim of the present study is to develop a national non-verbal cognitive ability test in Turkey. Test items were developed during the first stage and applied as a pilot study on 3,073 children in the age interval of 4 to 13. The test was given its final form based on the values of item difficulty, item distinctiveness, item total score…

Measurement of mental rotation presents a serious challenge to cognitive researchers owing to the lack of a single comprehensive measure that can be applied across the developing age groups. Objective of the present study was to develop and validate a new measure of mental rotation for preadolescent and adolescent age groups. Items were…

Item components that might contribute to the difficulty of items on the Raven Colored Progressive Matrices (CPM) and the Standard Progressive Matrices (SPM) were studied. Subjects providing responses to CPM items were 269 children aged 2 years 9 months to 11 years 8 months, most of whom were referred for testing as potentially gifted. A second…