Does a continuous measure of handedness predict reading processes and reading-related skills across the lifespan?

The purpose of this research was to investigate the relationship between handedness, reading skills, and reading-related cognitive processes. Although lateralised differences in brain functioning are well known, research regarding handedness, specific reading skills, and reading-related cognitive processes is ambiguous at best because handedness is often measured as a dichotomous variable rather than a continuous variable. This methodological difference contributes to the diverse research findings, therefore the present investigation addressed these methodological limitations. A large normative sample of up to 1383 participants who ranged in age from 4 to 80 completed the Woodcock Johnson Psycho-Educational Battery-Revised (Woodcock & Johnson, 1989a, 1989b) or the Woodcock Johnson Psycho-Educational Battery-Third Edition (Woodcock, McGrew, & Mather, 2001) in combination with the Dean Woodcock Sensory Motor Battery (Dean & Woodcock, 2003) lateral preference scale, a continuous measure of handedness. Polynomial multiple regression analyses indicated curvilinear relationships between handedness and reading skills, along with handedness and auditory working memory. Individuals towards the extremes of the handedness continuum performed less well on the reading-related tasks. Therefore, just knowing a general classification of right, left, or mixed handed will not provide significant knowledge regarding lateralisation or potential cognitive and academic consequences but rather knowledge of an individual's hand preference on a continuum may well be useful for evaluative purposes.