SYNESTHESIA

Synesthesia: is a perceptual condition of mixed sensations: a stimulus in one sensory modality (hearing) involuntarily elicits a sensation/experience in another modality (vision). Likewise, perception of a form (a letter) may induce an unusual perception in the same modality (a color). http://www.synesthete.org/







Grapheme-color synesthesia: this person perceive particular colors when seeing a letter, word or number (grapheme). Most of these studies have reported extra activations in the fusiform gyrus, which is known to be involved in color, letter and word processing. http://www.ncbi.nlm.nih.gov/pubmed/19302164 




Ordinal- linguistic personification: the involuntary and automatic tendency in certain individuals to attribute animate-like qualities such as personality and gender to sequential linguistic units (e.g., letters, numerals, days, months). http://portal.acm.org/citation.cfm?id=1245903




number-form synesthesia: consciously experience numbers in spatially-defined locations. For non-synesthete individuals, a similar association of numbers and space appears in the form of an implicit mental number line as signified by the distance effect–reaction time decreases as the numerical distance between compared numbers increases. 


Sound color synesthesia: In this type of synesthesia, when the person hears a certain sound they automatically think of a certain color in reaction to the first stimulus. It is sometimes described as "fireworks".  http://en.wikipedia.org/wiki/Synesthesia#Sound_.E2.86.92_color_synesthesia 



Lexical-gustatory synesthesia: This is the rarest type of synesthesia, where  a specific word awakes a taste in the gustatory glands. http://en.wikipedia.org/wiki/Synesthesia#Lexical_.E2.86.92_gustatory_synesthesia