A compositional shape code explains how we read jumbled words

We read words and even jubmled wrods effortlessly, but the neural representations underlying this remarkable ability remain unknown. We hypothesized that word processing is driven by a visual representation that is compositional i.e. with string responses systematically related to letters. To test this hypothesis, we devised a model in which neurons tuned to letter shape respond to longer strings by linearly summing letter responses. This letter model explained human performance in both visual search as well as word reading tasks. Brain imaging revealed that viewing a string activates this compositional letter code in the lateral occipital (LO) region, and that subsequent comparisons to known words are computed by the visual word form area (VWFA). Thus, seeing a word activates a compositional letter code that enables efficient reading.