Unconsciously deciphering handwriting: subliminal invariance for handwritten words in the visual word form area

Expert readers exhibit a remarkable ability to recognize handwriting, in spite of enormous variability in character shape-a competence whose cerebral underpinnings are unknown. Subliminal priming, combined with neuroimaging, can reveal which brain areas automatically compute an invariant representation of visual stimuli. Here, we used behavioral and fMRI priming to study the areas involved in invariant handwritten word recognition. Compared to printed words, easily readable handwritten words caused additional activity in ventral occipitotemporal cortex, particularly in the right hemisphere, while difficult handwriting also mobilized an attentional parietofrontal network. Remarkably, however, subliminal repetition effects were observed across printed and handwritten styles, whether easy or difficult to read, both behaviorally and in the activation of the left visual word form area (VWFA). These results indicate that the left inferotemporal VWFA possesses an unsuspected degree of fast and automatic visual invariance for handwritten words, although surprisingly this invariance can be reflected both as repetition suppression and as repetition enhancement.