The influence of reading expertise in mirror-letter perception: Evidence from beginning and expert readers

Abstract

The visual word recognition system recruits neuronal systems originally developed for object perception which are characterized by orientation insensitivity to mirror reversals. It has been proposed that during reading acquisition beginning readers have to "unlearn" this natural tolerance to mirror reversals in order to efficiently discriminate letters and words. Therefore, it is supposed that this unlearning process takes place in a gradual way and that reading expertise modulates mirror-letter discrimination. However, to date no supporting evidence for this has been obtained. We present data from an eye-movement study that investigated the degree of sensitivity to mirror-letters in a group of beginning readers and a group of expert readers. Participants had to decide which of the two strings presented on a screen corresponded to an auditorily presented word. Visual displays always included the correct target word and one distractor word. Results showed that those distractors that were the same as the target word except for the mirror lateralization of two internal letters attracted participants' attention more than distractors created by replacement of two internal letters. Interestingly, the time course of the effects was found to be different for the two groups, with beginning readers showing a greater tolerance (decreased sensitivity) to mirror-letters than expert readers. Implications of these findings are discussed within the framework of preceding evidence showing how reading expertise modulates letter identification.

Figure 1

Schematic representation of an experimental trial and examples of the target item and each distractor condition.

Figure 2

Probabilities of fixations on the target word (green markers) and on the distractor (red markers) in each display condition for the subgroup of beginning readers. Time is plotted on the x-axis (in 50ms-bin resolution). Error bars represent upper and lower 95% confidence limits, such that no overlap between conditions indicates a significant target-distractor difference. The solid black line in each graph corresponds to the time bin from which the two strings attracted significantly more (FDR-corrected) fixations.

Figure 3

Probabilities of fixations on the target word (green markers) and on the distractor (red markers) in each display condition for the subgroup of expert readers. Time is plotted on the x-axis (in 50ms-bin resolution). Error bars represent upper and lower 95% confidence limits, such that no overlap between conditions indicates a significant target-distractor difference. The solid black line in each graph corresponds to the time bin from which the two strings attracted significantly more (FDR-corrected) fixations.

Figure 4

Percentage of visual similarity between the items in the different conditions and the targets. Error bars represent upper and lower 95% confidence limits. All the statistical comparisons between conditions resulted significant (all ts>4 and ps<.001).