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…

The purpose of the present studies was to test the hypothesis that the psychometric characteristics of ability scales may be significantly distorted if one accounts for emotional factors during test taking. Specifically, the present studies evaluate the effects of anxiety and motivation on the item difficulties of the Rasch model. In Study 1, the…

Standardized tests are widely used in intellectual disability research, either as dependent or control variables. Yet, it is not certain that their items give rise to the same performance in various groups under study. In the present work, 48 participants with Down syndrome were matched on their raw score on Raven's Colored Progressive Matrices…

Background: Sentence construction and syntactic organization are known to be poor in children with specific language impairments (SLI), but little is known about the way in which children with SLI approach language tasks, and static standardized tests contribute little to the differentiation of skills within the population of children with…

This study was undertaken to shed light on problems concerning the construction and use of a common test battery for various South African population groups. Specifically, the psychometric suitability for use with Indian and Black pupils, of the Junior Aptitude Tests (JAT), which were standardized for White pupils in Standard 7 was studied. The…