Synesthetes get their senses muddled up – seeing sounds in colors, experiencing tastes as shapes, etc. Neurobiologist V.S. Ramachandran argues that not only is synesthesia common, but that we are all, to a degree, synesthetes. He’s devised a test to demonstrate. Q: Which of these two shapes is “booba” and which “kiki”? Click for answer and explanation.

If asked which of these two abstract shapes is "booba" and which is "kiki," 95-98 percent of respondents pick the blob as booba and the jagged shape as kiki. This is also true for non-English-speaking Tamillians for whom the shapes bear no resemblance to visual shapes of the Tamil alphabet corresponding to B or K. The effect demonstrates the brain's ability to engage in cross-modal abstraction of properties such as jaggedness or curviness

Ramachandran says that the visual shape and the sound of kiki share one property: "The kiki visual shape has a sharp inflexion and the sound 'kiki' represented in your auditory cortex, in the hearing centers of your brain, also has a sharp sudden inflection. Your brain performs a cross-modal synesthetic abstraction, recognizing that common property of jaggedness, extracting it, and so reaching the conclusion that they are both kiki."

Adapted and excerpted from A Brief Tour of Human Consciousness:From Impostor Poodles to Purple Numbers by V.S. Ramachandran (Pi Press, July 2004).