Synaesthesia: Prevalence and Familiality

Abstract

Synaesthesia is a condition in which a mixing of the senses occurs; for example, sounds trigger the experience of colour. Previous reports suggest this may be familial, but no systematic studies exist. In addition, there are no reliable prevalence or sex-ratio figures for the condition, which is essential for establishing if the reported sex ratio (female bias) is reliable, and if this implicates a sex-linked genetic mechanism. Two independent population studies were conducted in the city of Cambridge, England (studies 1 and 2 here), as necessary background to the family genetic study of synaesthesia (study 3). Studies 1 and 2 arrived at an almost identical prevalence rate for synaesthesia: approximately 1 case in 2000. The sex ratio found was 6:1 (female:male). A third of cases also reported familial aggregation. In study 3 six families were examined, and first-degree relatives were tested for genuineness of the condition. All six families were indeed multiplex for synaesthesia. Alternative modes of inheritance are discussed.

A deafening flash! Visual interference of auditory signal detection

“…The very predictability of visual-to-auditory correspondences might also counterintuitively explain why there have been so few reports of visually-evoked auditory concurrents (Baron-Cohen et al, 1996;Goller et al, 2009;Saenz & Koch, 2008). When a faint auditory sensation accompanies a visual event we might easily ignore it because it would not seem surprising or unusual.…”

“…This superior visual performance in synaesthetes was explained on the assumption that they were benefiting from additional temporal information provided by recoding the visual stimulation into the auditory modality (Glenberg, Mann, Altman, Forman, & Procise, 1989;Guttman, Gilroy, & Blake, 2006). Apart from other rare reports of individuals who hear distinct musical sounds associated with visual colours (Baron-Cohen, Burt, Smith-Laittan, Harrison, & Bolton, 1996;Goller, Otten, & Ward, 2009) there has been no other published research on this visual-to-auditory direction of association to our knowledge. Two unresolved questions are raised, which we consider here: how prevalent is this phenomenon, and is it perceptually real?…”

Monozygotic Twins' Colour-Number Association: a Case Study

“…The frequency of synaesthesia is a matter of some debate, with early estimates of perhaps 1 in 25,000, but the first systematic study suggesting 1 in 2000 (Baron-Cohen et al, 1996). However, a recent study (Mulvenna et al, 2004) found four cases from 445 participants, which suggests an incidence as high as 1 in 110.…”

That Sounds Sweet: Using Cross‐Modal Correspondences to Communicate Gustatory Attributes

“…Depending on the applied definition, the prevalence in the general population is estimated to lie somewhere between 1 in 2000 (Baron-Cohen, Burt, Smith-Laittan, Harrison, & Bolton, 1996) and 1 in 23 (Simner, et al, 2006). Roughness was influenced through the application of a tremolo effect with a constant modulation frequency of 70 Hz at varying modulation amplitudes (0% to 100%).…”