Abstract
For grapheme-color synesthetes, achromatic letters or digits appear to be inherently colored. This coupling between graphemes and colors has been suggested to be the result of hyperbinding, where synesthetes' cross-modal interactions are exaggerated compared to non-synesthetes. In the current study we used a priming paradigm in which primes and targets were presented to different sensory modalities (auditory and visual). In reaction time experiments, grapheme-color synesthetes and controls discriminated as fast and accurately as possible (1) the color of visual targets that were preceded by aurally presented digit primes, and (2) the identity of aurally presented digit targets that were preceded by visual color primes. The colors used were either congruent or incongruent to the synesthetic colors elicited by the digits used in the experiment. The results show that priming occurred bidirectionally across sensory modalities. When discriminating visual color targets preceded by aural digit primes, reaction times were longer when the color of the target was incongruent with the synesthetic percept reported (offline) for the prime. Likewise, when discriminating aurally presented digits targets preceded by visual color primes, reaction times were longer when the color of the prime was incongruent with the synesthetic percept for the target. These priming effects were absent in control subjects. Together, the results show that binding between graphemes and colors in grapheme-color synesthetes can occur bidirectionally across senses, thereby supporting the idea of hyperbinding in synesthetes. Moreover, they support the claim that, in spite of the explicit unidirectional nature, the coupling between grapheme and color in this form of synesthesia is bidirectional.
Meeting abstract presented at VSS 2014