Following this description of generic reading networks, largely based on Anglo-American and French literature, the lecture turned to the cultural variability of writing systems and their impact on reading mechanisms.
According to the neural recycling hypothesis, if the architecture of the human brain has not had the opportunity to evolve for reading, writing systems could, conversely, have evolved to take account of our brain's constraints. Could we then identify certain transcultural universals of writing and link them to the organization of the reader's brain? A brief examination reveals several universal aspects of writing systems :
- all require the sequential acquisition of word information by means of ocular saccades ;
- all feature a high density of high-contrast (typically black-on-white) strokes in the fovea of the retina ;
- all are based on a small repertoire of basic shapes whose hierarchical combinations form the characters ;
- all consider that the position and absolute size of characters are indifferent (presupposition of invariance).
Two remarkable invariants have recently been added to this list:
- Whatever the number of characters, the number of strokes per character is approximately constant (~ 3) (Changizi & Shimojo, 2005).
- The topology of traits within characters follows a reproducible distribution across cultures, the same as that observed in natural images (Changizi, Zhang, Ye, & Shimojo, 2006).
These data are compatible with the hypothesis that, in all cultures, the forms that mankind has given itself for its characters are those that are most easily encoded at the level of the inferotemporal cortex involved in visual object recognition.
