A cultural side effect: mirror suppression in object recognition is triggered by letter knowledge in preschoolers.

Abstract

Since when, during reading development, does literacy impact object recognition and orientation processing? Is this impact specific to mirror images (e.g., d − b) or also apparent for other transformations (e.g., plane−rotations: d − p)? To answer these questions, forty−six 5−7−year−old preliterate preschoolers and first graders performed two same−different matching tasks tapping explicit (orientation−based) vs. automatic (shape−based) orientation processing of geometric shapes. On orientation−based judgments, first graders outperformed preschoolers. Preschoolers had the strongest difficulty in discriminating mirrored pairs. On shape−based judgments, first graders were slower for mirrored than identical pairs, and even slower than preschoolers. This mirror cost, a side−effect of learning to read, was allied with letter knowledge in preschoolers. Thus, mirror suppression emerges even before formal literacy instruction and generalizes to non−linguistic material.