Adaptation of the human visual system to the statistics of letters and line configurations

Abstract

By adulthood, literate humans have been exposed to millions of visual scenes and pages of text. Does the human visual system become attuned to the statistics of its inputs? Using functional magnetic resonance imaging, we examined whether the brain responses to line configurations are proportional to their natural-scene frequency. To further distinguish prior cortical competence from adaptation induced by learning to read, we manipulated whether the selected configurations formed letters and whether they were presented on the horizontal meridian, the familiar location where words usually appear, or on the vertical meridian. While no natural-scene frequency effect was observed, we observed letter-status and letter frequency effects on bilateral occipital activation, mainly for horizontal stimuli. The findings suggest a reorganization of the visual pathway resulting from reading acquisition under genetic and connectional constraints. Even early retinotopic areas showed a stronger response to letters than to rotated versions of the same shapes, suggesting an early visual tuning to large visual features such as letters.

A Synoptic and Theoretical Account of Character (Digits and Capital Letters) Reversal in Writings by Typically Developing Children

“…Moreover, traces of this mirror generalization of characters can still be found in adults [18], at least in the case of non-reversible letters [19]. Not surprisingly, learning to read and handwrite the Latin alphabet increases the ability to discriminate mirror images [20,21], breaks mirror-invariance [22], and transforms the brain more generally [23,24]. According to a prominent theory, this mirror generalization for letters and words is due to the recycling of neurons in an area called the Visual Word Form Area (VWFA), which originally developed to recognize objects [25][26][27].…”

A Special Font for People with Dyslexia: Does it Work and, if so, why?

“…An important question is whether there would be reasons to expect cross-linguistic differences in the efficacy of Dyslexie font; for example, because the letter-sound mappings in English are less predictable than in Dutch (Frost, Katz, & Bentin, 1987;Schmalz, Marinus, Coltheart, & Castles, 2015). However, this generalization may not hold when comparing languages with different script types (e.g., alphabet vs. syllabary) or that have vastly different numbers of letters in their inventory (Chang et al, 2015). According to most contemporary reading theories, visual information such as the specific shape and size of letters is no longer relevant once the identities of the letters are determined.…”

“…4 In other words, because processing of font characteristics like letter type, size and spacing takes place in the early visual-processing stage of the reading process, font should not differentially influence reading across different languages (Perea et al, 2012). However, this generalization may not hold when comparing languages with different script types (e.g., alphabet vs. syllabary) or that have vastly different numbers of letters in their inventory (Chang et al, 2015).…”

Titchener’s ⊥ with its lines tilted—A partial replication and extension of Cormack and Cormack (1974)

“…One possibility is ontogenetic adaptation to a letter schema (cf. Chang et al, 2015). A test of this conjecture will have to comprise two steps at least: (1) a statistical survey of written Ts to establish that their upstrokes are typically longer than their cross-strokes, (2) a test of observers who are not (yet) thoroughly acquainted with this letter-for example, persons not using the Latin alphabet.…”

“…On the assumption that observers carry an internally distorted T-schema (the origin of which might either be acquired or innate), they will provide biased estimates of the lengths of the figure's two lines as long as it does not deviate too much from a prototype T (cf. Neisser, 1976, for a more elaborate discussion of schema theories; Changizi, Zhang, Ye, & Shimojo, 2006, for a possible origin of letter forms; Shevelev et al, 2001, for potentially relevant neurophysiological evidence in the cat; and Chang et al, 2015, for similar evidence in humans). On this account, contrary to Cormack and Cormack's (1974) reading of their data, the ⊥ illusion should always be largest at a 90°tilt between the figure's two lines.…”