Cognitive, Affective, & Behavioral Neuroscience

, Volume 4, Issue 3, pp 335–343 | Cite as

Not all synaesthetes are created equal: Projector versus associator synaesthetes

  • Mike J. DixonEmail author
  • Daniel Smilek
  • Philip M. Merikle


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.


Stroop Task Incongruent Trial Stroop Effect Color Naming Color Patch 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 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.CrossRefGoogle Scholar
  2. Baron-Cohen, S., Burt, L., Smith-Laittan, F., Harrison, J., & Bolton, P. (1996). Synaesthesia: Prevalence and familiarity. Perception, 25, 1073–1079.PubMedCrossRefGoogle Scholar
  3. 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.PubMedCrossRefGoogle Scholar
  4. 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.Google Scholar
  5. Chao, L. L., & Martin, A. (1999). Cortical regions associated with perceiving, naming, and knowing about colors. Journal of Cognitive Neuroscience, 11, 25–35.PubMedCrossRefGoogle Scholar
  6. Cohen, L., & Dehaene, S. (1995). Number processing in pure alexia: The effect of hemispheric asymmetries and task demands. Neuro-Case, 1, 121–137.Google Scholar
  7. Cytowic, R. E. (1993). The man who tasted shapes. New York: Warner.Google Scholar
  8. Cytowic, R. E. (2003). Synesthesia. A union of the senses. (2nd ed.). Cambridge, MA: MIT Press.Google Scholar
  9. 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.CrossRefGoogle Scholar
  10. Dixon, M. J., Smilek, D., Cudahy, C., & Merikle, P. M. (2000). Five plus two equals yellow. Nature, 406, 365.PubMedCrossRefGoogle Scholar
  11. 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.Google Scholar
  12. 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.PubMedCrossRefGoogle Scholar
  13. Gatti, S. V., & Egeth, H. E. (1978). Failure of spatial selectivity in vision. Bulletin of the Psychonomic Society, 11, 181–184.Google Scholar
  14. Grossenbacher, P. G., & Lovelace, C. T. (2001). Mechanisms of synesthesia: Cognitive and physiological constraints. Trends in Cognitive Sciences, 5, 36–41.PubMedCrossRefGoogle Scholar
  15. 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.CrossRefGoogle Scholar
  16. 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.PubMedCrossRefGoogle Scholar
  17. 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.PubMedCrossRefGoogle Scholar
  18. 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.CrossRefGoogle Scholar
  19. 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.Google Scholar
  20. 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.PubMedCrossRefGoogle Scholar
  21. 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.PubMedCrossRefGoogle Scholar
  22. 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.CrossRefGoogle Scholar
  23. 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.CrossRefGoogle Scholar
  24. 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.PubMedCrossRefGoogle Scholar
  25. 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.PubMedCrossRefGoogle Scholar
  26. 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.CrossRefGoogle Scholar
  27. 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.PubMedCrossRefGoogle Scholar
  28. 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.CrossRefGoogle Scholar
  29. 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.Google Scholar
  30. 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.CrossRefGoogle Scholar
  31. Ramachandran, V. S., & Hubbard, E. M. (2001b). Synaesthesia: A window into perception, thought and language. Journal of Consciousness Studies, 8, 3–34Google Scholar
  32. Schneider, W. (1990). MEL user’s guide: Computer techniques for real-time experimentation. Pittsburgh, PA: Psychology Software Tools.Google Scholar
  33. 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.CrossRefGoogle Scholar
  34. 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 Scholar
  35. Smilek, D., Dixon, M. J., Cudahy, C., & Merikle, P. M. (2001). Synaesthetic photisms influence visual perception. Journal of Cognitive Neuroscience, 13, 930–936.PubMedCrossRefGoogle Scholar
  36. Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643–662.CrossRefGoogle Scholar
  37. Svartdal, F., & Iversen, T. (1989). Consistency in synesthetic experience to vowels and consonants: Five case studies. Scandinavian Journal of Psychology, 30, 220–227.PubMedCrossRefGoogle Scholar
  38. 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.Google Scholar
  39. 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.Google Scholar
  40. Wollen, K. A., & Ruggiero, F. T. (1983). Colored-letter synaesthesia. Journal of Mental Imagery, 7, 83–86.Google Scholar
  41. Zeki, S., & Marini, L. (1998). Three cortical stages of colour processing in the human brain. Brain, 121, 1669–1685.PubMedCrossRefGoogle Scholar

Copyright information

© Psychonomic Society, Inc. 2004

Authors and Affiliations

  • Mike J. Dixon
    • 1
    Email author
  • Daniel Smilek
    • 1
  • Philip M. Merikle
    • 1
  1. 1.Department of PsychologyUniversity of WaterlooWaterlooCanada

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