Mental Rotation of Pictures, Letters and Symbols in Children with Dyslexia: Evidence for Stimulus Type Effect

Abstract

ABSTRACT We report the results of three tasks of two-dimensional pictures, letters and symbols mental rotation (MR) among 9–11 years aged Arabic readers with dyslexia, in order to examine a potential stimulus type effect on MR ability in terms of accuracy and speed. Results showed that readers with dyslexia (n = 32) performed significantly lower and were slower than typical readers (n = 44) in the three MR tasks. Furthermore, ‘group’ and ‘type of stimuli’ effects were obtained for accuracy and speed of MR implementation, indicating impaired visual spatial orientation processing in children with dyslexia. Furthermore, repeated measures of ANOVA showed that letter MR is significantly slower than pictures and symbols in dyslexic group but no difference in terms of accuracy. These results are interpreted as support for the notion of linguistic based mental rotation impairment in developmental dyslexia, without being restricted to orthographic material.