Analysis of the factor structure of processing speed

Processing speed is an important cognitive ability that impacts other cognitive and academic skills (Floyd, McGrew, & Evan, 2008; Naples, Katz, & Grigorenko, 2012; Vukivic & Siegel, 2010). Children with a variety of disabilities demonstrate processing speed significantly slower than their peers and as a result struggle in many areas (Floyd et al., 2008). Despite the importance of this construct, there is no consensus in the field of school psychology regarding the underlying structure of processing speed and what specific skills are included in its definition. This study used a database of neuropsychological assessment information for children with disabilities along with confirmatory factor analysis (CFA) to determine which of the main theories of processing speed best fits the patterns seen in this population. The theories tested include a one factor model, a model based on Cattell-Horn-Carroll (CHC) theory, and a model based on the Integrated School Neuropsychological (SNP)/CHC theory. The findings from the study indicated that all three models provide a poor to adequate representation of processing speed, with the Integrated SNP/CHC theory demonstrating slightly better fit than the other two models, but requiring the most modification. The results also implied that retrieval fluency correlates with and factors into processing speed, and that breaking processing speed into numerous third-level abilities does not result in a better representation of the construct. Understanding the underlying structure of processing speed will allow practitioners to better target both assessments and interventions when working with children with slower than average processing speed. Future research can examine whether these models demonstrate better fit with different data and populations as well as explore different models of processing speed.