Abstract
Introduction: Synesthesia is a phenomena that is marked by multi-sensory perceptions. Grapheme-color synesthetes experience color perceptions induced by viewing achromatic graphemes (numbers and letters presented in black text). Typically, the perceptions of these synesthetes have been considered to be unidirectional experience, meaning that numbers and letters induced certain colors but colors do not induce a sense of numbers or letters. Methods: In this study, we sought to examine the potential for colors to induce a sense of numerical value. Stimuli consisted of sets of color patches that corresponded with photisms perceived by the synesthete. For example, for a synesthete that associates 2 with red and 3 with blue, a stimulus would consist of red/blue patches ("23") and blue/red patches ("32"). Synesthetes and age matched controls were then presented with a forced-choice task in which they were required to indicate which of the two sequences demonstrated the highest magnitude. Results: Results indicated that synesthetes performed significantly different from chance while controls typically performed at chance. This data supports the possibility of synesthesia having bidirectional percepts, with colors that can evoke a sense of numerical magnitude. These bidirectional percepts suggest the potential for bidirectional communication between the underlying cortical regions responsible for processing these features.
Meeting abstract presented at VSS 2016