Synesthesia: Providing Colourful Insight into Mechanisms of Memory
Written by Amie Orsetti
Imagine that every time you see the number three it is hot pink, the number four is always lemon yellow, and five is dark blue. When you hear the word cup it tastes like pears, while the word chair tastes like pepper. Perhaps when you hear different music notes you feel raindrops down your arms, or you know that each day of the week has its own particular spot in space. These perceptual experiences exemplify a neurological condition called synesthesia, an everyday reality for approximately 4%-5% of the population (Spector & Maurer, 2013). While it may sound dramatic, people with the condition may not even be aware they have it. The word synesthesia means joined sensation (Bub, 2008), a fitting name for a condition where the brain makes unusual perceptual links between the sensations of taste, smell, hearing, vision and touch. These connections often foster creativity in people who experience them. Many famous musicians and artists have had the condition, including Duke Ellington, Nikolai Rimsky-Korsakov, and Tony DeCaprio (Pearce, 2007). Some people believe that Vincent van Gogh was also a synesthete (Bekker & Bekker, 2009).
In addition to enhancing artistry, synesthesia also impacts cognition. In particular, researchers have often used grapheme-colour synesthesia to study memory. Grapheme-colour synesthesia is a link between specific colours and both numbers and letters. Individuals with this type of synesthesia consistently experience the visual perception of certain colours when reading letters and words. The example given in the opening paragraph of seeing the number five as always being dark blue and four as always being yellow illustrates grapheme-colour synesthesia. This phenomenon is of interest to memory researchers, as many memory studies suggest that having multiple representations of an item strengthens our ability to recall it later. Since people with grapheme-colour synesthesia process both a verbal representation and also a colourful visual representation of words, this offers a unique opportunity to study mechanisms of memory.
Gosavi and Hubbard (2019) conducted two experiments that compared performance of synesthetes and nonsynesthetes on memory tasks. In one task, participants viewed a blank white screen before a matrix of black letters briefly flashed. The matrix contained three rows of three letters. After a very brief delay, participants were asked to report the letters they saw on either the top, middle, or bottom row, before moving on to the next matrix in the series. In another task, participants viewed matrices of symbols (i.e. !$#) rather than letters. The authors predicted that participants with synesthesia would outperform participants without synesthesia on the task involving letters, because participants receive dual information of both letter and colour. The authors also expected that participants with synesthesia would have no advantage on the task involving symbols, because the symbols contain no letter or colour information.
As predicted, participants with synesthesia demonstrated a better capacity for remembering letters than those without synesthesia. This advantage, however, was greatly reduced in the second task that used symbols. These results suggest that synesthetes have dual sources of information when observing stimuli, which leads to enhanced memory.
There were limitations to this study, notably the sample size was small with only 20 synesthetes and 20 nonsynesthetes in Experiment 1, and 17 per group in Experiment 2. This study also only assessed one aspect of memory and one type of synesthesia, so caution should be used when interpreting the results.
Synesthesia is a phenomenon that gives researchers a unique way to study perception and cognition. By using synesthesia to explore the mechanisms of memory, we can gain a better understanding of how our brains process information and make perceptual connections.
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References
Bekker, K. G., & Bekker, A. Y. (2009). Color and emotion - a psychophysical analysis of van Gogh's work. PsyArt.
Bub, B. (2008). Synesthesia. Academic Medicine, 83(7), 660-661. https://doi.org/10.1097/ACM.0b013e31817eb5ab
Gosavi, R. S., & Hubbard, E. M. (2019). A colorful advantage in iconic memory. Cognition, 187, 32-37.
https://doi.org/10.1016/j.cognition.2019.02.009
Pearce, J. M. S. (2007). Synaesthesia. European Neurology, 57(2), 120-124. https://doi.org/10.1159/000098101
Spector, F., & Maurer, D. (2013). Synesthesia: A new approach to understanding the development of perception.
Psychology of Consciousness: Theory, Research, and Practice, 1(S), 108–129. https://doi.org/10.1037/2326-
5523.1.S.108
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The blog posts are for informational and educational purposes only. The posts should not be considered as any type of advice (medical, mental health, legal, and/or religious advice). All blog posts have been researched, written, and edited by the undergraduate students and alumni of the Lifespan Cognition Lab. As a teaching and research-based lab, we encourage all lab members to help make knowledge more accessible to all communities through these posts.
