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Synaesthesia, hypnosis and consciousness

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posted on 2023-06-08, 20:58 authored by Hazel Patricia Anderson
For people with synaesthesia, a percept or concept (inducer) triggers another experience (concurrent) which is usually in a different modality. The concurrent is automatic, and in the case of certain types of synaesthesia also consistent, however the relationship between the inducer and concurrent is not fully understood and shall be investigated in this thesis from different perspectives. The first is using hypnosis to suggest synaesthesia-like phenomenological experiences to participants, and measuring behavioural responses to see whether they behave in a similar manner to developmental synaesthetes. Results from hypnotic; 1) grapheme-colour (GC) synaesthesia; 2) motion-sound synaesthesia; suggest that phenomenological experiences similar to developmental synaesthesia can be experienced by highly susceptible participants, but is not associated with the same behaviour as developmental synaesthetes. Developmental GC synaesthetes were tested to determine whether a grapheme presented preconsciously binds with the concurrent colour to the extent that it influences behaviour or evokes the phenomenology of colour. Two techniques were used, gaze-contingent substitution (GCS) and continuous flash suppression (CFS). Using GCS, it was shown that although digits can be primed preconsciously, they don’t bind with their concurrent colour to influence behaviour. Nevertheless, many synaesthetes still experienced colours though they didn’t necessarily match the primed digit. CFS experiments showed that the colour of a grapheme’s concurrent, or whether the grapheme is presented in the correct or incorrect colour for that synaesthete, doesn’t influence the time for conscious perception of a grapheme, even though colour words presented in the correct colour are perceived faster than those in the wrong colour. Phenomenological differences were compared to the behavioural measures using questionnaires modified using factor analysis (the R-RSPA and R-ISEQ). Overall, inducers must be seen consciously for them to bind with the concurrent, and experiencing the phenomenology of synaesthesia is not sufficient to behave like a synaesthete.


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