The time course of synaesthetic colour perception

Grapheme–colour synaesthesia is a neurodevelopmental condition wherein perception of numbers and letters consistently involuntarily elicits concurrent experiences colour photisms. Accumulating evidence suggests that heterogeneity in the visuospatial phenomenology attributable to operation top-down processes underlying photisms experienced as representations associator synaesthetes bottom-up subserving spatially localized projector synaesthetes. An untested corollary this hypothesis mechanisms will actuate earlier photism than We tested prediction pre-registered study associators projectors completed adaptive temporal order judgement tasks for graphemes, colours, In corroboration differential access across subtypes, displayed lower thresholds whereas two subtypes did not significantly differ veridical thresholds. Synaesthetes grapheme or relative non-synaesthete controls. These results are consistent with proposal neural grapheme–colour warrant renewed attention condition.