A number of test batteries are used to identify children with motor dificulties such as dyspraxia, developmental coordination disorder (DCD) or motor learning dificulties (MLD). These batteries implicitly assume a higher order construct since they provide a composite score as an indicator of overall motor performance. In this study, we use Burton and Rodgerson’s (2001) theoretical taxonomy of motor behavior to guide the interpretation of an assessment tool. In this study we investigated the hierarchical structure of the McCarron Assessment of Neuromuscular Development (MAND) (McCarron, 1982) to ascertain the irst order factors and whether there were higher order factors. The MAND battery has 10 items measuring a range of motor skills noted below. Motor scores were obtained from a subsample of 1,619 ten-year-olds (boys = 842, girls = 777) from the longitudinal Western Australian Pregnancy Cohort (Raine) Study. Principal components analysis with Promax rotation yielded three factors with eigenvalues ≥ 1 and explained 49% of the variance. The irst 1st order factor, which we called stability, explained 26% of the variance and included one foot stand, heel-toe walk, inger-nose, rod-slide and inger tap (factor loadings .69 - .39). The second factor, called dexterity, explained 12% of the variance and comprised nut and bolt, beads on rod and beads in box (factor loadings .74 - .71). The third 1st order factor, called muscle power, explained 11% of the variance and included grip strength and standing broad jump (factor loadings .84 - .60). All three 1st order factor scores were used in the second order principal component analysis. Only one component, with an eigenvalue ≥ 1, was extracted, which explained 45% of the variance. All three 1st order factors contributed providing psychometric evidence of a higher order abstract construct. The irst order factors were consistent with movement skill foundations as represented in Burton and Rodgerson’s (2001) taxonomy, but did not support a taxonomic division into ine and gross motor skill sets. The second order factor is consistent with their general motor ability construct. In order to achieve a high score on the McCarron battery, a child had to respond to complex and varied motor task demands often in an unfamiliar environment. There is a need for further debate and research into the meaning of higher order constructs. For example, are we measuring motor ability or kinaesthetic intelligence?
Larkin, D., Hands, B., Parker, H., Kendall, G., & Sloan, N. (2007). Are we measuring motor ability? Paper presented at the Progress in Motor Control VI Conference. Santos, Brazil, 9-12 August.