Synaesthesia: The Prevalence of Atypical Cross-Modal Experiences

Questions:

(1) Why? Why was this research conducted? What is the hypothesis? The paper I chose is titled, “Synaesthesia: The prevalence of atypical cross-modal experiences” (Simner et al., 2006). The research was conducted to determine the frequency of synesthesia (also spelled Synaesthesia) using objective measures and without the use of self-referral. The hypothesis is that synesthesia frequency and prevalence estimates may be faulty due to a heavy reliance on self-reporting. Because we can learn something about normal development by studying cases where sensory modularity breaks down there is a need to have accurate figures regarding the frequency and forms of synesthesia.

(2) Who? Whom are they studying? The study recruited 500 (327 Female, 173 male) participants from the Edinburgh and Glasgow Universities. Although it is not stated, presumably the majority of these individuals were college students. In a second study, they recruited 1190 English-speaking visitors to the London’s Science Museum (June – August 2004).

(3) How? How did they do the research? In the University study, the subjects were given spoken and written descriptions of what synesthesia was and was not. They were then asked to self-report any associations they had between “triggers” (letters, English words, foreign words, names, addresses/places, numbers, days months, voices, pains/touches, movements/postures, music, noises, shapes/patterns, smells, tastes, colors, and emotions) and a list of “experiences” (colors, smells, pains, shapes, tastes, noises, flashes, music, movements). Subjects were removed who may have been suffering from medical conditions or whose experience may have been caused by recreational drug use. The group was divided into synesthesia and control groups. The test was to associate letters, numbers, days, months, words, foodstuffs names, and 40 smells and 70 tones and asked to write down their associated percept. Each group was then given a surprise retest, after a number of weeks. For the Museum test, subjects were given a computerized test in which 36 graphemes (a-z, and 0-9) were shown in a random order. The subjects then selected a color from a 13-color pallet that they associated with the grapheme. The subjects were then given an immediate surprise retest in which the presentation of graphemes and colors was randomized.

(4) What? What were the results of their study? What did they find out? Conventional wisdom was that synesthesia is extremely rare, occurring in about 0.05% of births, and that women were affected more frequently then men. The data concluded that synesthesia occurs far more frequently, about 88 times higher or about 4.4% of the population, than previously thought. They also showed that the most common variant is colored days, and that there is no difference between women and men. The form of synesthesia that was previously thought to be the most common occurs in at a frequency of about 1%.

(5) What? What did they think these results mean? What are the implications for practical application, or for further research? The primary finding and implication of this research is that there are far more people who experience synesthesia than previously thought. They also speculate that the previously held belief that women experience synesthesia more frequently than men may not be true. They believe this is due to a bias for female self-reporting in previous studies. They also discuss weaknesses of their study. Subjects who reported atypical synesthesia experiences, for example shapes for taste or special orientations for specific letters and numbers, were excluded from the study. Further research may show that these experiences are new and unrecognized manifestations of synesthesia.  

Reference

Simner, J., Mulvenna, C., Sagiv, N., Tsakanikos, E., Witherby, S. A., Fraser, C., … Ward, J. (2006). Synaesthesia: The prevalence of atypical cross-modal experiences. Perception 35, 1024-1033.