On the relationships between processing speed, intra-subject variability, working memory, and fluid intelligence – A cross-sectional study

• Published in: Intelligence (Norwood) Vol. 105; p. 101836
• Main Authors: Schulz-Zhecheva, Y., Voelkle, M.C., Biscaldi, M., Beauducel, A., Klein, C.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.07.2024
• Subjects: Developmental cascade model; Intelligence; Intra-subject variability; Processing speed; Working memory; Developmental cascade model; Processing speed; Working memory; Intra-subject variability; Intelligence
• ISSN: 0160-2896; 1873-7935
• DOI: 10.1016/j.intell.2024.101836

The developmental cascade model, elaborated by Fry and Hale (2000) emphasizes the role of age-related increases in processing speed and working memory for the development of fluid intelligence. Given the intimate relationships between intra-subject variability and the aforementioned constructs, the present study set out to determine the role of intra-subject variability within the pathways outlined in the developmental cascade model, postulating a fundamental role of intra-subject variability for the development of processing speed, working memory and fluid intelligence. To that end, N = 403 participants aged 8–18 years took a testing battery including choice reaction time tasks to measure processing speed and intra-subject variability as well as span, operation span and coordination tasks to measure working memory within the empirical framework of Oberauer et al. (2003). Cattell's Culture Fair Test (CFT-20 R) was used to measure fluid intelligence. Our results confirm the well-known close relationships between processing speed, working memory, and fluid intelligence, and show that intra-subject variability is also closely related to these constructs. The results of the present study suggest the extension of the developmental cascade model by the inclusion of intra-subject variability as a fundamental construct. •The cascade model, elaborated by Fry and Hale (2000), has been a highly influential model of cognitive development, emphasizing the role of processing speed (PS) and working memory (WM) for the development of fluid intelligence (gf).•In a cross-sectional study, we tested a sample of children and adolescents using a large battery of tests.•Based on a sample of N = 403 children and adolescents we confirm here the relationships between PS, WM and gf and extend this network of constructs by intra-subject variability (ISV) as another fundamental construct of an extended cascade model.