In synaesthesia, ordinary stimuli elicit extraordinary experiences. When grapheme-color synaesthetes view black text, each grapheme elicits a photism—a highly specific experience of color. Importantly, some synaesthetes (projectors) report experiencing their photisms in external space, whereas other synaesthetes (associators) report experiencing their photisms “in the mind’s eye.” We showed that projectors and associators can be differentiated not only by their subjective reports, but also by their performance on Stroop tasks. Digits were presented in colors that were either congruent or incongruent with the synaesthetes’ photisms. The synaesthetes named either the video colors of the digits or the colors of the photisms elicited by the digits. The results revealed systematic differences in the patterns of Stroop interference between projectors and associators. Converging evidence from first-person reports and third-person objective measures of Stroop interference establish the projector/ associator distinction as an important individual difference in grapheme-color synaesthesia.
Allison, T., McCarthy, G., Nobre, A., Puce, A., & Belger, A. (1994). Human extrastriate visual cortex and the perception of faces, words, numbers, and colors. Cerebral Cortex, 5, 544–554.
Baron-Cohen, S., Burt, L., Smith-Laittan, F., Harrison, J., & Bolton, P. (1996). Synaesthesia: Prevalence and familiarity. Perception, 25, 1073–1079.
Baron-Cohen, S., Harrison, J., Goldstein, L. H., & Wyke, M. (1993). Coloured speech perception: Is synaesthesia what happens when modularity breaks down? Perception, 22, 419–426.
Blake, R., Palmeri, T. J., Marois, R., & Chai, Y.-K. (in press). On the perceptual reality of synesthetic colors. In L. Robertson & N. Sagiv (Eds.), Synesthesia: Perspectives from cognitive neuroscience. New York: Oxford University Press.
Chao, L. L., & Martin, A. (1999). Cortical regions associated with perceiving, naming, and knowing about colors. Journal of Cognitive Neuroscience, 11, 25–35.
Cohen, L., & Dehaene, S. (1995). Number processing in pure alexia: The effect of hemispheric asymmetries and task demands. Neuro-Case, 1, 121–137.
Cytowic, R. E. (1993). The man who tasted shapes. New York: Warner.
Cytowic, R. E. (2003). Synesthesia. A union of the senses. (2nd ed.). Cambridge, MA: MIT Press.
Di Lollo, V., Enns, J. T., & Rensink, R. A. (2000). Competition for consciousness among visual events: The psychophysics of reentrant visual pathways. Journal of Experimental Psychology: General, 129, 481–507.
Dixon, M. J., Smilek, D., Cudahy, C., & Merikle, P. M. (2000). Five plus two equals yellow. Nature, 406, 365.
Dixon, M. J., Smilek, D., Wagar, B. M., & Merikle, P. M. (2004). Grapheme-color synaesthesia: When 7 is yellow and D is blue. In G. A. Calvert, C. Spence, & B. E. Stein (Eds.), Handbook of multisensory processes (pp. 837–849). Cambridge, MA: MIT Press.
Elias, L. J., Saucier, D. M., Hardie, C., & Sarty, G. E. (2003). Dissociating semantic and perceptual components of synaesthesia: Behavioural and functional neuroanatomical investigations. Cognitive Brain Research, 16, 232–237.
Gatti, S. V., & Egeth, H. E. (1978). Failure of spatial selectivity in vision. Bulletin of the Psychonomic Society, 11, 181–184.
Grossenbacher, P. G., & Lovelace, C. T. (2001). Mechanisms of synesthesia: Cognitive and physiological constraints. Trends in Cognitive Sciences, 5, 36–41.
Gulyas, B., Heywood, C. A., Popplewell, D. A., Roland, P. E., Cowey, A. (1994). Visual form discrimination from color or motion cues: Functional anatomy by positron emission tomography. Proceedings of the National Academy of Sciences, 91, 9965–9969.
Hadjikhani, N., Liu, A. K., Dale, A. M., Cavanagh, P., & Tootell, R. B. H. (1998). Retinotopy and color sensitivity in human visual cortical area V8. Nature Neuroscience, 1, 235–241.
Lueck, C. J., Zeki, S., Friston, K. J., Deiber, M.-P., Cope, P., Cunningham, V. J., Lammertsma, A. A., Kennard, C., & Frackowiak, R. S. J. (1989). The colour centre in the cerebral cortex of man. Nature, 340, 386–389.
MacLeod, C. M., & Dunbar, K. (1988). Training and Stroop-like interference: Evidence for a continuum of automaticity. Journal of Experimental Psychology: Learning, Memory, & Cognition, 14, 126–135.
Mattingley, J. B., & Rich, A. N. (2004). Behavioral and brain correlates of multisensory experience in synaesthesia. In G. A. Calvert, C. Spence, & B. E. Stein (Eds.), Handbook of multisensory processes (pp. 851–865). Cambridge, MA: MIT Press.
Mattingley, J. B., Rich, A. N., Yelland, G., & Bradshaw, J. L. (2001). Unconscious priming eliminates automatic binding of colour and alphanumeric form in synaesthesia. Nature, 410, 580–582.
McKeefry, D. J., & Zeki, S. (1997). The position and topography of the human colour centre as revealed by functional magnetic resonance imaging. Brain, 120, 2229–2242.
Mills, C. B., Boteler, E. H., & Oliver, G. K. (1999). Digit synaesthesia: A case study using a Stroop-type test. Cognitive Neuropsychology, 16, 181–191.
Myles, K. M., Dixon, M. J., Smilek, D., & Merikle, P. M. (2003). Seeing double: The role of meaning in alphanumeric- colour synaesthesia. Brain & Cognition, 53, 342–345.
Nunn, J. A., Gregory, L. J., Brammer, M., Williams, S. C., Parslow, D. M., Morgan, M. J., Morris, R. G., Bullmore, E. T., Baron-Cohen, S., & Gray, J. A. (2002). Functional magnetic resonance imaging of synesthesia: Activation of V4/V8 by spoken words. Nature Neuroscience, 5, 371–375.
Odgaard, E. C., Flowers, J. H., & Bradman, H. L. (1999). An investigation of the cognitive and perceptual dynamics of a colour-digit synaesthete. Perception, 28, 651–664.
Palmeri, T. J., Blake, R., Marois, R., Flanery, M. A., & Whetsell, W., Jr. (2002). The perceptual reality of synesthetic colors. Proceedings of the National Academy of Sciences, 99, 4127–4131.
Paulesu, E., Harrison, J., Baron-Cohen, S., Watson, J. D. G., Goldstein, L., Heather, J., Frackowiak, R. S. J., & Frith, C. D. (1995). The physiology of coloured hearing: A PET activation study of colour-word synaesthesia. Brain, 118, 661–676.
Polk, T. A., & Farah, M. J. (1998). The neural development and organization of letter recognition: Evidence from functional neuroimaging, computational modeling, and behavioral studies. Proceedings of the National Academy of Sciences, 95, 847–852.
Posner, M. I., & Snyder, C. R. R. (1975). Attention and cognitive control. In R. L. Solso (Ed.), Information processing and cognition: The Loyola symposium (pp. 55–85). Hillsdale, NJ: Erlbaum.
Ramachandran, V. S., & Hubbard, E. M. (2001a). Psychological investigations into the neural basis of synaesthesia. Proceedings of the Royal Society of London, 268, 979–983.
Ramachandran, V. S., & Hubbard, E. M. (2001b). Synaesthesia: A window into perception, thought and language. Journal of Consciousness Studies, 8, 3–34
Schneider, W. (1990). MEL user’s guide: Computer techniques for real-time experimentation. Pittsburgh, PA: Psychology Software Tools.
Shiffrin, R. M., & Schneider, W. (1977). Controlled and automatic human information processing: II. Perceptual learning, automatic attending, and a general theory. Psychological Review, 84, 127–190.
Smilek, D., & Dixon, M. J. (2002). Towards a synergistic understanding of synaesthesia: Combining current experimental findings with synaesthetes’ subjective descriptions. Psyche, 08. Retrieved July 1, 2003 from http://psyche.cs.monash.edu.au/v8/psyche-8-01-smilek.html.
Smilek, D., Dixon, M. J., Cudahy, C., & Merikle, P. M. (2001). Synaesthetic photisms influence visual perception. Journal of Cognitive Neuroscience, 13, 930–936.
Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643–662.
Svartdal, F., & Iversen, T. (1989). Consistency in synesthetic experience to vowels and consonants: Five case studies. Scandinavian Journal of Psychology, 30, 220–227.
Van Selst, M., & Jolicoeur, P. (1994). A solution to the effects of sample size on outlier elimination. Quarterly Journal of Experimental Psychology, 47A, 631–650.
Wagar, B. M., Dixon, M. J., Smilek, D., & Cudahy, C. (2002). Colored photisms prevent object-substitution masking in digit-color synesthesia. Brain & Cognition, 48, 606–611.
Wollen, K. A., & Ruggiero, F. T. (1983). Colored-letter synaesthesia. Journal of Mental Imagery, 7, 83–86.
Zeki, S., & Marini, L. (1998). Three cortical stages of colour processing in the human brain. Brain, 121, 1669–1685.
The Natural Sciences and Engineering Research Council of Canada funded this research with operating grants awarded to the first and third authors and a postgraduate scholarship awarded to the second author.
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Dixon, M.J., Smilek, D. & Merikle, P.M. Not all synaesthetes are created equal: Projector versus associator synaesthetes. Cognitive, Affective, & Behavioral Neuroscience 4, 335–343 (2004). https://doi.org/10.3758/CABN.4.3.335
- Stroop Task
- Incongruent Trial
- Stroop Effect
- Color Naming
- Color Patch