The reading level matched design: limitations and possible alternatives

Wybrow & Hanley (2015) reported that proportions of phonological and surface dyslexics change depending on how control groups are selected. This observation questions the appropriateness of the reading-level match design for establishing causality in cognitive studies of reading. Here, I focus on three features: (1) the lack of an explicit definition of the reading-level concept; (2) the metric problems associated with using this design; and (3) the ambiguity of the delay-deviance contrast in interpreting reading deficits. I also delineate alternative methodological features that could effectively inform developmental designs. Thus, I argue that (a) control variables should be as independent of the target-dependent measure as possible; (b) they should be shaped within the theoretical aims of the study and be explicitly considered in the interpretation of findings; and, (c) conditions of interest should be viewed along with critically associated conditions using approaches that allow predicting the size of the expected deficit.