 Furthermore, the area of the brain where word, letter and color processing are located, V4a, is where the most significant difference in make-up was found.Though not certain, these differences are thought to be part of the reasoning for the presence of grapheme–color synesthesia.Synesthetes often report that they were unaware their experiences were unusual until they realized other people did not have them, while others report feeling as if they had been keeping a secret their entire lives.