Synaesthesia lost and found: two cases of person‐ and music‐colour synaesthesia

Abstract

Synaesthesia is a developmental condition involving cross-communication between sensory modalities or substreams whereby an inducer (e.g. a sound) automatically evokes a concurrent percept in another modality (e.g. a colour). Whether this condition arises due to atypical structural connectivity (e.g., between normally unconnected cortical areas) or altered neurochemistry remains a central question. We report the exceptional cases of two synaesthetes - subjects AB and CD - both of whom experience coloured auras around individuals, as well as coloured perceptions in response to music. Both subjects have, in recent years, suffered a complete loss or reduction of their synaesthetic experiences, one (AB) through successive head traumas, including a lightning strike, followed by a number of medications, and the other (CD) while taking anxiolytic medications. Using semi-structured interviews and data from the Synaesthesia Battery and a colourpicker task, we characterize the phenomenological characteristics of their pre-loss synaesthesia, as well as the subsequent restoration of each subject's synaesthetic experiences (in the months post-trauma for AB, and after cessation of medication for CD). Even after years of suppression, the patterns of associations were highly consistent with those experienced pre-injury. The phenomenological experience of synaesthesia can, thus, like most conscious experiences, be modulated by pharmacologically diverse medications or head injury. However, the underlying neural substrates mediating specific synaesthetic pairings appear remarkably 'hard-wired' and can persist over very long periods even under conditions that alter or completely suppress the conscious synaesthetic experience itself.

An extended research of crossmodal correspondence between color and sound in psychology and cognitive ergonomics

“…Research on crossmodal correspondences between sound and color has a long history in the field of experimental psychology. Crossmodal correspondences between color and auditory stimuli are well-established in the literature, especially in synesthetes ( Karwoski, Odbert & Osgood, 1942 ; Cytowic, 2002 ; Day, 2005 ; Ward, Huckstep & Tsakanikos, 2006 ; Hänggi et al, 2008 ; Spector & Maurer, 2009 ; Menouti et al, 2015 ; Farina, Mitchell & Roche, 2016 ). For example, most synesthetes tend to associate high pitch sounds with light colors—middle ‘C’ on a piano might be red but the note three octaves higher might be green.…”

The chemical induction of synaesthesia

“…Accumulating evidence suggests that synaesthesia has a genetic basis (Tilot et al., 2018), although individual associations seem to be shaped mostly by environmental constraints in early development (Witthoft & Winawer, 2013) and remain highly automatic and consistent over time in adulthood (Eagleman et al., 2007; Rothen et al., 2013). Synaesthesia typically emerges in early stages of development (Simner et al., 2009), although there have been multiple reports of adult‐onset cases following stroke, drug use, physical trauma, and neuropathology (Brogaard, 2013; Farina et al., 2017; Ro et al., 2007; Yanakieva et al., 2019).…”