A structural model for developmental change in the determinants of reading ability

Developmentally dependent changes in the neuropsychological correlates of reading achievement were examined via the analysis of linear structural relations, or LISREL (Joreskog, 1976). The study tested the hypothesis that the relative importance of non-verbal/perceptual skills and verbal-conceptual skills in reading changed as a function of development and that non-verbal/perceptual skills became increasingly less important with age. Data were taken from a previously completed six-year longitudinal study of learning disabilities in Alachua County, Florida (Satz, Taylor, Friel, and Fletcher, 1978). A sub-sample of 222 white males from the original study sample was used for the present study. Three measures of non-verbal/perceptual skills and three measures of verbal conceptual skills were collected at each of three measurement periods, namely in Kindergarten, at the end of Grade 2, and at the end of Grade 5. In addition, a standardized test of word recognition and a teacher based report of the child's instructional book level were obtained at the Grade 2 and Grade 5 assessment periods. These 22 measures were incorporated into a three-wave three-factor structural equation model with correlated errors, the parameters of which were estimated via the computer program LISREL V (Joreskog and Sorbom, 1981). The model stipulated that each of the 22 variables loaded on only a single factor, and that each of the non-verbal and verbal skills factors were measured by three variables, while the reading achievement factors were each measured by two variables. [...]