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Updated: Apr 7, 2026

Training Synesthetic Letter-color Associations by Reading in Color
Published on: February 20, 2014
Geminate consonant grapheme-colour synaesthesia (ideaesthesia)
Donald F Weaver1,2,3, Cassandra L A Hawco4,5
1Toronto Western Research Institute, 60 Leonard Avenue, Toronto, ON, M5T 2S8, Canada. dweaver@uhnresearch.ca.
Background:
Synaesthesia is a neurological condition which manifests clinically as an involuntary experience of a sensory or cognitive pathway upon stimulation of a second unrelated sensory or cognitive pathway
Case Presentation:
We report a 55 year old male who presented with a life-long history of grapheme-colour synaesthesia in which the triggering grapheme was the double letter 'll' (a geminate consonant), but not 'l' as a single letter. This patient's synaesthesia was also font specific (becoming more evident with serif fonts) and influenced by migraine headache (being suppressed during the prodrome and aura of a migraine headache)
Conclusion:
These results suggest that geminate consonants are uniquely processed rather than treated as two individual consonants. Also, the existence of a mechanistic relationship between synesthetic and migrainous events sequence was verified.
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