When 9 is not on the right: implications from number-form synesthesia.
Number-form synesthetes 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. In the current experiment, three number-form synesthetes and two different non-synesthete control groups (Hebrew speaking and English speaking) performed a number comparison task. Synesthete participants exhibited a sizeable distance effect only when presented numbers were congruent with their number-form. In contrast, the controls exhibited a distance effect regardless of congruency or presentation type. The findings suggest that: (a) number-form synesthesia impairs the ability to represent numbers in a flexible manner according to task demands; (b) number-form synesthesia is a genuine tangible experience, triggered involuntarily; and (c) the classic mental number line can be more pliable than previously thought and appears to be independent of cultural-lingo direction.
Gertner
Limor
L
Department of Psychology and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, P.O. Box 635, Beer-Sheva 84105, Israel. limorger@bgu.ac.il
Henik
Avishai
A
Cohen Kadosh
Roi
R
D000328:Adult; D001244:Association; D001364:Awareness; D003210:Concept Formation; D003220:Conflict, Psychological; D003431:Cross-Cultural Comparison; D004192:Discrimination, Psychological; D004215:Distance Perception; D004739:England; D005260:Female; D006801:Humans; D007092:Imagination; D007557:Israel; D007802:Language; D008297:Male; D008433:Mathematics; D009949:Orientation; D010364:Pattern Recognition, Visual; D011340:Problem Solving; D011930:Reaction Time; D012016:Reference Values; D013028:Space Perception; D055815:Young Adult