Revisiting letter transpositions within and across morphemic boundaries.

Early morphological decomposition of complex words has been supported by evidence showing that the magnitude of masked transposed-letter (TL) priming effects is greater for within-morpheme transpositions than for between-morpheme transpositions. However, these findings have lately been called into question, and a recent article by Sánchez-Gutiérrez and Rastle (Psychonomic Bulletin & Review, 20, 988-996, 2013) suggested that the above-mentioned interaction could have been the consequence of a false positive (i.e., a Type I error). Considering recent evidence showing that morpho-orthographic interactions are highly sensitive to individual differences in reading skills, we explored whether participants' averaged reading speeds were responsible for modulating the size of within- versus between-morpheme TL priming effects. A large-scale lexical decision experiment with a set of 420 suffixed Spanish words (N = 80 participants) was run using the masked-priming technique. The results revealed that individual differences modulated the magnitude of the masked TL priming effect between morphemes: Faster readers (but not slower readers) yielded greater TL priming for within- than for between-morpheme transpositions. The present data help reconcile previous divergent data by showing that faster readers revealed a morpho-orthographic interaction, whereas slower readers may rely more on a morphological-processing strategy that is not sensitive to morpho-orthographic interactions.