Abstract
—Background— Written words are unrecognizable outside a small, central region of the visual field (the “field of view”). Common explanations include a drop in acuity and increase in crowding. We hypothesize that the field of view is also determined by factors specific to reading. For instance, words are easier to recognize in the right than left hemifield. One explanation for the hemifield asymmetry is the lateralization of the brain’s reading circuitry to the left hemisphere. —Methods— We measured word recognition accuracy in a lexical decision task as a function of stimulus position along the horizontal meridian, from 6° left to 6° right. We also developed a “flanked gap task” with strings of shapes matched in size and spacing to the words. One of the inner shapes had a gap in the top or bottom. The subject reported which side had the gap. Finally, in the “unflanked gap task,” the target shape appeared alone with no flankers. —Results— Accuracy in the unflanked gap task was consistently near ceiling, demonstrating that acuity was not a limiting factor. In contrast, accuracy in the flanked gap and lexical decision tasks fell off rapidly with eccentricity. The eccentricity effect was highly correlated across the two tasks (mean r=0.87), suggesting that common mechanisms (i.e., crowding) impair both types of shape recognition. However, the two tasks differed in that lexical decision accuracy was better in the right than left hemifield. The hemifield asymmetry suggests that reading is constrained by domain-specific neural mechanisms. Indeed, the behavioral data match the asymmetric field of view of word-selective visual cortex (the “visual word form area”), measured as the aggregation of its population receptive fields. —Conclusion— The field of view for words cannot be fully accounted for by general visual mechanisms and may depend on the spatial tuning of word-selective cortex.