Prevalence of Learned Grapheme-Color Pairings in a Large Online Sample of Synesthetes

Authors

Nathan Withhoft, Department of Psychology, Stanford University, Stanford, California, USAFollow
Jonathan Winawer, Department of Psychology and Center for Neural Science, New York University, New York, New York, USA
David M. Eagleman, Baylor College of Medicine, Houston, TX, USAFollow

Publication Date

3-4-2015

Journal

PLoS One

DOI

10.1371/journal.pone.0118996

PMID

25739095

PMCID

PMC4349591

PubMedCentral® Posted Date

March 2015

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

synaesthesia; synesthesia; synesthete; grapheme

Abstract

In this paper we estimate the minimum prevalence of grapheme-color synesthetes with letter-color matches learned from an external stimulus, by analyzing a large sample of English-speaking grapheme-color synesthetes. We find that at least 6% (400/6588 participants) of the total sample learned many of their matches from a widely available colored letter toy. Among those born in the decade after the toy began to be manufactured, the proportion of synesthetes with learned letter-color pairings approaches 15% for some 5-year periods. Among those born 5 years or more before it was manufactured, none have colors learned from the toy. Analysis of the letter-color matching data suggests the only difference between synesthetes with matches to the toy and those without is exposure to the stimulus. These data indicate learning of letter-color pairings from external contingencies can occur in a substantial fraction of synesthetes, and are consistent with the hypothesis that grapheme-color synesthesia is a kind of conditioned mental imagery.