Report on Research Study: "Learning, Memory and Synesthesia" - Nathan Witthoft & Jonathan Winawer
Published in: Psychological Science: 2013 24: 258
Witthoft and Winawer investigate synesthesia, a condition whereby an individual experiences the involuntary stimulation of a cognitive or sensory pathway when another, distinct pathway is stimulated. The participants of this study specifically suffer from color-grapheme synesthesia. These individuals “experience color when viewing letters or numerals”.
Witthoft and Winawer challenge the hypothesis that these involuntary associations are influenced by learning and memory. The paper suggests that the very nature of synesthesia is the “automatic retrieval of highly specific [learned] mnemonic associations”. This concept draws from the supposition that grapheme-color synesthetes learn color-number or color-letter associations from childhood toys. This study contrasts others, which have focused on the biological underpinnings of synesthesia. Thus the classic debate of nature (genetics and biological perception) versus nurture (learning from the environment) is reignited.
Participants were obtained through a variety of means. Witthoft and Winawer placed advertisements for the study on the American Synesthesia Association Web site and also found willing participants at Synesthesia research centers. All eleven of the color-grapheme synesthetes in the study were born in the USA between 1970 and 1985. In ten out of the eleven cases, the participants claimed to have owned or still currently own a very common letter toy. Witthoft and Winawer wanted to test whether learned associations of the colored toy contributed towards synesthesia.
The research involved the use of The Synesthesia Battery website, which actually tests for the condition. The research participants engaged in a color-letter matching task. All letters of the alphabet and the single numerical digits were presented to them one at a time, and the participants were asked to adjust the “color picker” on a computer software to match the synesthetic color regarding each letter and number. Each subject had two matching sessions.
A high degree of likeness between the color-letter pairings between participants was ostensible. In spite of this strong similarity, the researchers did notice that there were some subtle distinctions relating to the exact hue of the color matched to each letter.
The color-number matches were not as consistent, however. This may have been because of the fact that of the 11 research participants, only Subjects 2, 3, 4, and 6 unambiguously remembered having colored number toys.
From a purely methodological point of view, testing was certainly not extensive enough to reach any concrete conclusions regarding the initially proposed hypothesis. The scope of the experiment is extremely limited. With tens of thousands of synesthetes in the US alone, a sample of eleven participants is nowhere near large enough to be representative of the population. The means by which subjects were gathered is also questionable. Participants were aware that the study involved the toy letter set. Could this lack of blindedness have enforced bias?
Finally, while the research tested for colors associated with given letters and numbers, perhaps a control would be to test if colors stimulated a cognitive pathway for the letters or numbers themselves. From a psychological viewpoint, the hypothesis is not invalid. It is psychological dogma that our environment influences long-term memory, which can last a lifetime. However, more research would have to be done to provide conclusive results regarding color-grapheme synesthesia. The paper does succeed, however, in putting forth an interesting hypothesis.