In hearing people visual word recognition relies on a hierarchical organization in left ventral occipitotemporal (vOT) cortex. While right hemisphere recruitment has been implicated in poor reading, this may not be the case for deaf readers as there is evidence that for skilled deaf readers the right vOT is also engaged during word recognition. However, the nature of representations along the vOT hierarchy and the degree of laterality in skilled deaf readers remain largely unknown. This study aimed to examine the hierarchical organization for written words in the vOT bilaterally for skill-matched deaf and hearing readers to determine whether deafness and phonological ability modulates the laterality of word-selectivity gradients. Using fMRI, we employed the same design as previous studies, presenting stimuli that represent a scale of orthographic regularity: consonant strings, pseudowords, and real words. For hearing readers, our results replicate previous findings showing a hierarchical structure solely in the left visual word form system (VWFS).For deaf readers, we find this same hierarchical structure in the left VWFS, but we also observe a similar hierarchical structure in the right VWFS. Unlike studies that show maladaptive right hemisphere activation in people with dyslexia, the bilateral tuning to written words seen in our study is not maladaptive since all participants were skilled readers. The bilateral hierarchical organization of the VWFS represents a unique neural signature for successful reading in deaf adults and suggests that the typical developmental shift from bilateral to predominantly left-lateralized processing is not necessary for successful reading.

The existence of a neural representation for whole words (i.e., a lexicon) is a common feature of many models of speech processing. Prior studies have provided evidence for a visual lexicon containing representations of whole written words in an area of the ventral visual stream known as the visual word form area . Similar experimental support for an auditory lexicon containing representations of spoken words has yet to be shown. Using functional magnetic resonance imaging rapid adaptation techniques, we provide evidence for an auditory lexicon in the auditory word form area in the human left anterior superior temporal gyrus that contains representations highly selective for individual spoken words. Furthermore, we show that familiarization with novel auditory words sharpens the selectivity of their representations in the auditory word form area. These findings reveal strong parallels in how the brain represents written and spoken words, showing convergent processing strategies across modalities in the visual and auditory ventral streams.