The Role of Attention in Grapheme - Color Synesthesia

Grapheme-color synesthesia is a unique neurological condition in which affected individuals report experiencing strong and consistent associations between specific colors and graphemes (letters or numbers). The current study used electroencephalography (EEG) neuroimaging techniques to address two primary research questions: 1. Does the brain activity of grapheme-color synesthetes reflect the neural processing of synesthetic color associations and if so, how and when? 2. Are synesthetic color associations processed pre-attentively, or do they require focused attention to be perceived? To answer these questions, the brain activity of ten grapheme-color synesthetes and ten matched control participants was recorded during exposure to grapheme stimuli in two separate experiments. The first experiment revealed an early event-related potential (ERP) component related to the neural processing of synesthetic color associations. The second experiment revealed behavioral and electrophysiological differences between synesthetes and controls on a visual search task, suggesting that synesthetic color associations are processed pre-attentively or under conditions of minimal attentional allocation.