From the Lab to the Classroom: Bridging Psychophysics and Psychometrics to Improve Adaptive Dyslexia Screening

As children learn to read, two skills develop in parallel: the complexity of words they can decode and the speed at which the word recognition system operates. Reading assessments capture these processes using both timed and untimed tasks, yet it remains unclear whether word processing speed and word complexity reflect separable dimensions of reading ability or two manifestations of the same underlying skill. Here, we independently manipulated word complexity and presentation time in a lexical decision task to test whether they constitute distinct axes of reading development. Through a research–practice partnership, we collected large-scale developmental data from 3,194 students spanning Grades 1–12 in the United States (English) and Brazil (Portuguese). Results showed that items presented with infinite presentation time were systematically less difficult but required longer response times than items presented under fast conditions for students with and without dyslexia across development. Importantly, word processing speed and word difficulty were well characterized by a unidimensional framework, suggesting that the increasing speed and complexity observed during reading development reflect a common underlying skill. We then leveraged these findings to design and validate a novel multi-stage adaptive-timing approach for dyslexia screening (N=14,393 calibration sample; N=841 validation sample). Results from a K–2 validation study showed that this approach improved screening precision and efficiency for beginning readers. By integrating the experimental precision of Psychophysics with scalable measurement frameworks in Psychometrics, this work illustrates how insights from basic science can be translated into universal school-based screening practices for early dyslexia identification.