Synaesthesia Honours Project: Classifications cont.
Continuation from reading the book “Sensory Blending: On Synaesthesia and related phenomena” (Deroy, 2017).
Previous blog entry ended up on synaesthesia classification by Ophelia Deroy.
Cognitive-perceptual and perceptual-cognitive synaesthesia:
Wheeler and Cutsforth (1922a, 1922b) by experimenting on blind synesthete they got to conclusion that the phenomenon is not only perceptual but also a cognitive process.
It’s well known that grapheme-color synesthetes (Grapheme-color synaesthesia is a form of synesthesia in which an individual's perception of numerals and letters is associated with the experience of colors (En.wikipedia.org, 2018)) can see colors not only when they look but also when they think about letters and numbers.
Perceptual-affective and cognitive-affective synaesthesia
Perceptual-affective: Flournoy (1893) and Calkins (1893,1895) report of Personification; synesthete is matching numbers or letters with attributes of person or other object like “U is soulless”, “3 I cannot trust, thought it is fairly good-looking in person appearance”. These attributions show many of the same characteristics in other forms of synaesthesia (Simner and Holenstein (2007). Emotional attributes have been associated with synaesthesia by some investigators. Werner (1957) conclude that it is a physiognomic (physiognomy is a practice of assessing a person's character or personality from their outer appearance (En.wikipedia.org, 2018) property of visual perception that objects can be associate with emotional attributes like purple as noble, grey as sad and yellow as happy (non-scientific examples). Personification not only as form of synaesthesia but also a paradigm form (Werner, 1934).
Cognitive-affective: recently discovered in twenty-first century is mirror-touch synaesthesia. One example is a woman who reported that sight of another person (that was next to her but in opposite mirrored side) being touched evoked sensation in an equivalent region of her body. There’s possibility of connections between synaesthesia and empathy. Empathetic pain as variant of synaesthesia is still in question.
Synaesthesia can be distinguished between projection and association: inductants projected into the external space of the inducer (when colour is seen) and inductants perceived ‘in the mind’s eye’. Dixon et al. (2004).
Common research practice to determine occurrence of synaesthesia:
High level of consistency in inducer-inductant relations over time are necessary to classify if a given person in synesthetic (because e.g. strong visual imaginary in response to music might fall somewhere between synaesthesia and synesthetic tendency). Every grapheme should induce same colour, word or flavour not only automatically but also repeatedly over long intervals of time like months or even decades (which have been observed already). Participants who do not pass a test of consistency are commonly excluded from experiments.
Reductionistic approach (Reductionism is any of several related philosophical ideas regarding the associations between phenomena which can be described in terms of other simpler or more fundamental phenomena (En.wikipedia.org, 2018)): seeks to discover genetic, neuroanatomical and neurophysiological mechanisms responsible for idiopathic (developmental) synaesthesia.
Neural substrates (A neural substrate is a term used in neuroscience to indicate a part of the nervous or brain system that underlies a specific behavior or psychological state. Neuralis an adjective relating to "a nerve or the nervous system", while a substrate is an "underlying substance or layer" (En.wikipedia.org, 2018)) are seen as responsible for some forms of synaesthesia like grapheme-color (e.g., Hubbard and Ramachandran, 2005; Hubbard et al., 2005). Some points generic propensity to develop synesthesia (e.g., Barnett et al., 2008; Asher et al., 2009). Genes, processes or neural networks were not identified yet.
“The difference between the experiences of synesthetes and non-synesthetes may reflect differences in neuroanatomy. It is possible that grapheme-color synesthetes and non-synesthetes differ because the synesthetes have neural connections between ensembles of neurons responsible for processing graphemes and ensembles processing color (Ramachandran and Hubbard, 2001). (p.35) And synesthetes and non-synesthetes may differ in their neuroanatomy because synesthetes are born with, or are programmed to develop” (Deroy, 2017)
Vivid synesthetic perception: when musical notes evoke sensation of colour.
Cross-modal imagery: music leads to visual images of colour or patterns (but not necessarily automatically or with great consistency)
Cross-modal similarity in perception: no vivid synaesthesia or cross-modal imagery but still perceive e.g. low tones as dark colours (this example was mentioned by one student two weeks ago, now I can tell him more about his experience).
Cross-modal similarity in language: no vivid synaesthesia or cross-modal imagery but metaphorically interpret words ‘squeak’ and ‘sneeze’ to connote brightness, the words ‘thunder’ and ‘cough’ darkness. This is something every musician (or anyone who create music) know very well as such descriptions are hard-witted to musical language (not professional but used by professionals) e.g. warm is the sound where higher frequency range is toned down and area of 200-700Hz is prominent, cold is the sound that have prominent higher frequency range and flat low to mid-range.
Figure 1 Schematic representation of monoism, dualism and pluralism. Taken from book: Sensory Blending On Synaesthesia and related phenomena p.45 (Deroy, 2007)
Figure 1 show us that in Monism boundaries between synaesthetic and non-synesthetic are abolished and gradually fade between each other while in Pluralism and Dualism these differences are separated.
Figure 2 Pluralistic model of synaesthesia. Taken from book: Sensory Blending On Synaesthesia and related phenomena p.45 (Deroy, 2007)
Visual hearing and colored and pattern hearing falls into synaesthesia category in Figure 2.
Osgood (e.g., Osgood, 1960; Osgood et al., 1957) argued that the meanings inherent in auditory-visual synesthesia (sound induced colours, shapes, and patterns) are connotative (feelings that people connect with the word).
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. American Journal of Human Genetics, 84, 279–85.
Barnett, K.J., Finucane, C., Asher, J.E., Bargary, G., Corvin, A.P., Newell, F.N., & Mitchell, K.J. (2008). Familial patterns and the origins of individual differences in synaesthesia. Cognition, 106, 871–93.
Calkins, M.W. (1893). A statistical study of pseudochromesthesia and mental-forms. American Journal of Psychology, 5, 439–64. Calkins, M.W. (1895). Synaesthesia. American Journal of Psychology, 7, 90–107.
Deroy, O. (2017). Sensory blending. Oxford: Oxford University Press, pp.16, 66.
Dixon, M.J., Smilek, D., & Merikle, P.M. (2004). Not all synaesthetes are created equal: Distinguishing between projector and associator synaesthetes. Cognitive, Affective, and Behavioral Neuroscience, 4, 335–43.
En.wikipedia.org. (2018). Grapheme-color synesthesia. [online] Available at: https://en.wikipedia.org/wiki/Grapheme-color_synesthesia [Accessed 22 Oct. 2018].
Flournoy, T. (1893). Des phénomènes de synopsie [Phenomena of synopsia] Paris: Alcan.
Hubbard, E.M., Arman, A.C., Ramachandran, V.S., & Boynton G.M. (2005). Individual differences among grapheme-color synesthetes: brain-behavior correlations. Neuron, 45, 975–85.
Ramachandran, V., & Hubbard, E.M. (2001). Synaesthesia—a window into perception, thought and language. Journal of Consciousness Studies, 8, 3–34.
Simner, J., & Holenstein, E. (2007). Ordinal linguistic personification as a variant of synesthesia. Journal of Cognitive Neuroscience, 19, 694–703.
Werner, H. (1957). Comparative psychology of mental development (rev. ed.). New York: International Universities Press.
Wheeler, R.H., & Cutsforth, T.D. (1922a). The synaesthesia of a blind subject with comparative data from an asynaesthetic blind subject. University of Oregon Publications, 1, 10, 1–104.
Wheeler, R.H., & Cutsforth, T.D. (1922b). Synaesthesia and meaning. American Journal of Psychology, 33, 361–84.
Deroy, O. (2017). Sensory blending : On synaesthesia and related phenomena (First ed.).