Fernandes, TâniaVelasco, SofiaLeite, Isabel2024-03-132024-03-132023-09-22Fernandes, T., Velasco, S., & Leite, I. (2023). Letters away from the looking glass: Developmental trajectory of mirrored and rotated letter processing within words. Developmental Science, 27(2), e13447. https://doi.org/10.1111/desc.134471363-755Xhttp://hdl.handle.net/10451/63385Discrimination of reversible mirrored letters (e.g., d and b) poses a challenge when learning to read as it requires overcoming mirror invariance, an evolutionaryold perceptual tendency of processing mirror images as equivalent. The present study investigated when, in reading development, mirror-image discrimination becomes automatic during visual word recognition. The developmental trajectory of masked priming effects was investigated from 2nd to 6th grade and in adults, by manipulating letter type (nonreversible; reversible) and prime condition (control; identity; mirrored; rotated). Standardized identity priming increased along reading development. Beginning readers showed mirror invariance during reversible and nonreversible letter processing. A mirror cost (slower word recognition in mirrored-letter than identity prime condition) was found by 5th-grade but only for reversible letters. By 6th grade, orthographic processing was no longer captive of mirror invariance. A multiple linear regression showed that letter representations, but not phonological processes or age, were a reliable predictor of the rise of mirror-image discrimination in 2nd–4th-graders. The present results suggest a protracted development of automatic mirror-image discrimination during orthographic processing, contingent upon the quality of abstract letter representations.engLetter representationMasked primingMirror imagesOrthographic processingReading developmentVisual word recognitionjournal article2024-03-09cv-prod-350984410.1111/desc.134471467-7687