Phenomenal and Experimental approaches to synesthetic experience of Korean color-graphemic synesthetes

공감각은 한 종류의 특정한 감각을 경험할 때 다른 감각 경험이 동시에 일어나는 현상으로 최근 심리학 및 신경과학 분야에서 주목받고 있는 연구 주제 중 하나이다. 본 연구에서는 최초로 한국인 공감각자를 표집하여 알파벳, 숫자, 한글 자모음에서 보고되는 공감각 현상의 주관적 특성을 기술하였으며 실험에 의한 객관적 증명을 시도하였다. 실험 1의 공감각 스트룹 과제에서는 물리적 색과 공감각 색의 간섭 효과를 통해 공감각 경험의 자동성을 검증하였다. 한글 자모음을 자극으로 사용하여 제시된 자극의 물리적 색이 그 자극에서 야기되는 공감각 색과 불일치하는 경우, 일치하는 경우에 비해 반응시간이 길어지는 효과를 관찰하였다. 실험 2의 시각 탐지 과제에서는 인위적인 학습을 통한 연합이 재현할 수 없는 공감각 경험 고유의 지각적 실재성을 검증하였다. 서로 다른 공감각색을 유발하는 방해 자극과 목표 자극을 사용하여 탐지 과제를 실시했을 때, 자극 개수가 늘어남에 따라 반응 시간이 증가하였다. 이때 일반인 집단의 반응 시간 증가율에 비해 공감각자 집단의 증가율이 낮았다. 이는 공감각 색 경험이 시각탐지 과제에서 실제 색과 유사한 방식으로 탐지 효율을 증가시킨 결과로 해석된다. 본 논문은 표집된 한국인 공감각자들이 보고한 통계적이고 현상적인 특성과 실험의 결과를 종합하여 공감각 경험의 진위 여부를 입증한 최초의 보고로 그 의의를 지닌다.

keywords: 공감각, 한글, 스트룹 과제, 자동성, 시각 탐지 과제, 지각적 실재성, Syensthesia, Han-gul, the Stroop effect, Automaticity, Visual search task, Perceptual reality, Syensthesia, Han-gul, the Stroop effect, Automaticity, Visual search task, Perceptual reality

Abstract

Synesthesia is a condition under which a stimulus in one sensory modality induces unusual perceptual experience in another sensory modality. Here we report Korean synesthetes who experience colors when viewing alphanumeric characters. This study not only describes phenomenal aspects of synesthetic color experiences associated with graphemes including Korean alphabet (“Han-gul”) but also verifies authenticity and perceptual reality of synesthetic experience by exploiting a couple of experimental paradigms. Experiment 1 utilized a synesthetic version of the Stroop task to verify the automaticity of synesthetic experience. By presenting a Korean grapheme either in physical color matching the observer's synesthetic color experienced by the grapheme(the congruent condition) or in a “wrong” color(the incongruent condition), we observed increased reaction time when the physical color doesn't match synesthetic color, which reveals interference of synesthetic color in real color judgment. Experiment 2 exploited a visual search task to verify perceptual reality of syensthetic color. When a target inducing synesthetic color was located among many distracters inducing different synesthetic color, the set-size effect(i.e., increase in reaction time as the number of stimulus increases) from synesthetic observers was reduced compared to that from non-synesthetic observers. The result shows that synesthetic color improved search efficiency as real color does in ordinary visual search task. This study is by far the first report on Korean color-graphemic syesthetes integrating both phenomenal and experimental aspects of their synesthetic color experiences.

keywords: 공감각, 한글, 스트룹 과제, 자동성, 시각 탐지 과제, 지각적 실재성, Syensthesia, Han-gul, the Stroop effect, Automaticity, Visual search task, Perceptual reality, Syensthesia, Han-gul, the Stroop effect, Automaticity, Visual search task, Perceptual reality

참고문헌

Asher, J. E., Lamb, J. A., Brocklebank, D., Cazier, J. B., Maestrini, E., Addis, L., Sen, M., Baron-Cohen, S., . . . Monaco, A. P. (2009). A whole-genome scan and fine-mapping linkage study of auditory-visual synesthesia reveals evidence of linkage to chromosomes 2q24, 5q33, 6p12, and 12p12. The American Journal of Human Genetics 84, 1-7.

Bargary, G. & Mitchell, K. J. (2008). Synaesthesia and cortical connectivity. Trends in Neuroscience 31 (7), 335-342.

Barnett, K., Newell, F., Finucane, C., Asher, J., Corvin, A., & Mitchell, K. (2008). Familial patterns and the origins of individual differences in synaesthesia. Cortex 106, 871–893.

Baron-Cohen, S. & Harrison, J. (1997). Synaesthesia: classic and contemporary readings. Cambridge, MA: Blackwell.

Baron-Cohen, S., Burt, L., Smith-Laittan, F., Harrison, J., & Bolton, P. (1996). Synaesthesia: Prevalence and familiality. Perception 25, 1073–1079.

Blake, R., Palmeri, T. J., Marois, R., & Kim, C-Y., (2005). On the perceptual reality of synesthetic color, In L. Robertson & N. Sagiv (Eds.), Synesthesia: Perspectives from Cognitive Neuroscience (47-73). Oxford: Oxford University Press.

Brainard, D. H. (1997). The Psychophysics Toolbox. Spatial Vision 10, 433–436.

Cytowic, R. E. (1989). Synesthesia: a Union of the Senses. New York: Springer.

Cytowic, R. E. (1993). The Man Who Tasted Shapes. London: Abacus.

10.

Cytowic, R. & Eagleman, D. (2009). Wednesday is indigo blue. MA: MIT Press.

11.

Day, S. (2005). Some Demographic and Socio-cultural Aspects of Synesthesia, In L. Robertson & N. Sagiv (Eds.), Synesthesia: Perspectives from Cognitive Neuroscience (47-73). Oxford: Oxford University Press.

12.

Dixon, M. J. & Smilek, D. (2005). The Importance of Individual Differences in Grapheme-Color Synesthesia. Neuron 45 (6), Pages 821-823.

13.

Dixon, M. J., Smilek, D., Cudahy, C. & Merikle, P. M. (2000). Five plus two equals yellow. Nature (London) 406, 365.

14.

Domino, G. (1989). Synaesthesia and creativity in fine arts students: An empirical look. Creativity Research Journal 2 (1–2), 17–29.

15.

Duffy, P. L. (2001). Blue cats and chartreuse kittens: How synesthetes color their worlds. New York: Henry Holt.

16.

Eagleman, D. M., Kagana, A. D., Nelson, S. S.,Sagaram, D., & Sarma, A. K. (2007). Standardized test battery for the study of synesthesia. Journal of Neuroscience Methods 159, 139-145.

17.

Hubbard, E. M. & Ramachandran, V. S., (2001b). Synaesthesia—A Window Into Perception, Thought and Language. Journal of Consciousness Studies 8 (12), 3–34.

18.

Hubbard, E. M. & Ramachandran, V. S., (2005). Neurocognitive mechanisms of Synesthesia. Neuron 48, 509-520.

19.

Galton, F. (1880a). Visualized numerals. Nature 21, 252-256.

20.

Galton, F. (1880b). Visualized numerals. Nature 22, 494-495.

21.

Galton, F. (1883). Inquiries into Human Faculty and Its Development. London: Dent.

22.

Kadosh, R. C., Henik, A., Catena, A., Walsh, V., & Fuentes, L. J., (2009). Induced Cross-Modal Synaesthetic Experience Without Abnormal Neuronal Connections. Psychological Science 20 (2), 258-265.

23.

Kadosh, R. C., Kadosh, C. K., & Henik, A. (2007). The Neuronal Correlate of Bidirectional Synesthesia: A combined Event-related Potential and Functional Magnetic Resonance Imaging study. Journal of Cognitive Neuroscience 19, (12), 2050-2059.

24.

Kim, C-Y. & Blake, R. (2005). Last but not least: Watercolor illusion induced by synesthetic colors, Perception 34, 1501-1507.

25.

Mattingley, J. B., Rich, A. N., Yelland, G., & Bradshaw J. L. (2001). Unconscious priming eliminates automatic binding of colour and alphanumeric form in synesthesia. Nature 410, 580-582.

26.

Mills, C. B., Boteler, E. H., & Oliver, G. K. (1999). Digit synesthesia: A case study using a stroop-type test. Cognitive Neuropsychology 16 (2), 181-191.

27.

Palmeri, T. J., Blake, R., Marois, R., Flanery, M. A., & Whetsell W. (2002). The perceptual reality of synesthetic colors. Proceedings of the National Academy of Sciences 99 (6), 4127-4131.

28.

Pelli, D. G. (1997). The VideoToolbox software for visual psychophysics: Transforming numbers into movies. Spatial Vision 10, 437–442.

29.

Rich, A. N., Bradshaw, J. L., & Mattingley, J. B. (2005). A systematic, large-scale study of synaesthesia: Implications for the role of early experience in lexical-colour associations. Cognition 98 (1), 53-84.

30.

Sagiv, N. & Robertson, L. C., (2005). SYNESTHESIA: Perspectives from Cognitive Neuroscience. New York: Oxford University Press.

31.

Simner, J., Mulvenna, C., Sagiv, N., Tsakanikos, E., Witherby, S. A., Fraser, C., Scott, K., . . . Ward, J. (2006). Synaesthesia: The prevalence of atypical cross-modal experiences. Perception 35, 1024–1033.

32.

Simner, J., Glover, L., & Mowat, A. (2006). Linguistic Determinants of Word Colouring in Grapheme-Colour Synaesthesia. Cortex 42 (2), 281-289.

33.

Smilek, D., Dixon, M. J., & Merikle, P. M.,(2003). Synaesthetic photisms guide attention. Brain and Cognition 53 (2), Pages 364-367.

34.

Smilek, D., Moffatt, B. A., Pasternak, J., White, B.N., Dixon, M. J. & Merikle, P. M. (2002). Synaesthesia: a case study of discordant monozygotic twins. Neurocase 8, 338–342.

35.

Smilek, D., Dixon, M. J., Cudahy, C., & Merikle, P. M. (2001). Synaesthetic photisms influence visual perception. Journal of Cognitive Neuroscience 13, 930-936.

36.

Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology 18, 643-662.

37.

Ward, J., Li, R., Salih, S. & Sagiv, N. (2007). Varieties of grapheme-colour synaesthesia: A new theory of phenomenological and behavioural differences. Consciousness and Cognition 16, 913–931.

38.

Weiss, P., Shah, J. N., Toni, I., Zilles, K. & Fink, G. R. (2001). Associating Colours with People: A Case of Chromatic-Lexical Synaesthesia. Cortex 37 (5), Pages 750-753.

39.

Witthoft, N. & Winawer, J. (2006). Synesthetic Colors Determined by Having Colored Refrigerator Magnets in Childhood. Cortex 42 (2), Pages 175-183.

바로가기메뉴

논문 상세

Vol.21 No.4

한국인 색-자소 공감각자의 공감각 경험에 대한 현상적 기술 및 실험적 입증

Phenomenal and Experimental approaches to synesthetic experience of Korean color-graphemic synesthetes

초록

Abstract

참고문헌

한국심리학회지: 인지 및 생물