Examining the Etiology of Reading Disability as Conceptualized by the Hybrid Model

Abstract

A fairly recent definition of reading disability (RD) is that in the form of a hybrid model. The model views RD as a latent construct that is manifested through various observable unexpected impairments in reading related skills and through inadequate response to intervention. The current report evaluated this new conceptualization of RD from an etiological perspective. The sample consisted of 2737 twin pairs in first through fourth grade (M_age = 8.52) from the Florida Twin Project on Reading. Using twin analyses, results showed that a substantial proportion of genetic variance, a small proportion of shared environmental, and a small proportion of non-shared environmental variance was attributed to the RD factor. Findings suggest that the etiological architecture of RD closely mirrors the structure of the hybrid model of RD.

Keywords: environmental; genetic; hybrid model; reading disability; twins.

Figure 1

Left panel: Spencer et al.’s (2014) hybrid model of RD. Right panel: Common pathway model for the Spencer et al.’s (2014) hybrid model. RD = reading disability, RC = reading comprehension, LC = listening comprehension, RTI = response to intervention.

Figure 2

Common pathway model for the Spencer et al.’s (2014) hybrid model with standardized path coefficients; significant paths are in bold [95% confidence intervals]. RD = reading disability, RC = reading comprehension, LC = listening comprehension, RTI = response to intervention.