Synaesthesia: the prevalence of atypical cross-modal experiences.
Level 4 - case-series / case-control
Cross-sectional screening and prevalence study with objective verification
PubMed 17076063 · doi:10.1068/p5469
What was done
The authors conducted a prevalence study of synaesthesia using a sampling method independent of self-referral and applied objective testing to verify the genuineness of reported cross-modal experiences.
What was found
Synaesthesia prevalence was 88 times higher than previously assumed (historical estimate: 0.05% of births). Coloured days was the most common variant, grapheme-colour synaesthesia had a prevalence of 1%, and no strong asymmetry across sexes was observed. Exact participant counts, confidence intervals, and test metrics were not reported in the abstract.
Why it matters
This paper refutes the traditional views that synaesthesia is extremely rare and female-predominant, showing it is substantially more prevalent when avoiding self-referral bias.
Limits
The abstract does not state the sample size (n), participant demographics, response rates, or the exact nature and cut-offs of the objective tests used.