Synesthesia is going to be the discussion topic for our upcoming neuroslam in two weeks. Synesthesia is the rare ability of a select few individuals to see numbers as colors or as in the article that I’m preparing to discuss (Hubbard 1996), experience varying degrees of light and dark as melodic intervals. The observed pattern is that individuals experience lower pitches or descending melodic intervals in correlation with darker stimuli and higher pitches or ascending melodic intervals in correlation with lighter stimuli. The important detail about synesthesia is that individuals experience it involuntarily whereas most individuals without synesthesia can choose to consider a set of stimuli using a secondary sense that they normally wouldn’t.
One of the experiments discussed in this article was conducted with undergraduate students coaxed into participating with the offer of some credit for an intro to psychology course. The students were placed in front of an Apple RGB color monitor and grey squares of differing light intensities were presented in conjunction with a perfect fifth for four seconds. Eight perfect fifths were used, each beginning on a different tonic and thus each having a unique frequency. The squares were presented on either a white or black background. The students then rated how similar the square and the interval were on a scale with one as the least and nine as the most. One of the questions considered with this experiment is the effect of contrast between the background and the grey squares on perception.
A second experiment was set up similar to the first experiment except that students (who had not participated in the first experiment) were presented with an interval at one of the selected frequencies and asked to choose among several light intensities of grey which correlated best. Correlating one perfect fifth to a light intensity that was presented with multiple light intensity options successfully diminished (no pun intended) the effects of background contrast on perception.
I thought of some questions when I was reading this article and then afterward studying for music theory. Are there individuals who experience synesthesia such that they correlate varying degrees and intensities of lightness with more complex types of music intervals? Do minor or diminished intervals correlate to a different light intensity than major or augmented intervals? What about different intervals of the same quality? Do ascending minor sixths correlate to a different light intensity than ascending minor thirds? If an individual with true synesthesia enters a concert hall do they experience sensory overload? (just kidding) I’m sure one of us neurobio students will post about neuroslam in a couple weeks to fill everyone in on our discussions but until then there is a lot of good reading on the subject.
Timothy L. Hubbard. “Synesthesia-like mappings of lighness, pitch, and melodic interval.” American Journal of Psychology. 1996. v109n2: p219