Synaesthesia: The Strangest Thing (review)

A valuable addition to the literature on synesthesia (as we Americans spell it), John Harrison's book presents a cogent analysis of the phenomenon, which will appeal to scientists and to the general public. While the work focuses on a series of experiments on colored hearing directed by Harrison's mentor Simon Baron-Cohen, it provides a careful exposé of the historical and scientific framework of those experiments. Harrison's discussion of the changing historical nature of evidence in experimental psychology is particularly welcome and sheds light on a whole range of disciplines where cognitive processes are the object of scientific investigation. His chapter on notable synesthetes, while not integral to his argument, proceeds gracefully and will be of particular interest to those unfamiliar with synesthesia. The crux of his argument, hierarchically developed over anatomical, physiological, and psychological hypotheses on synesthesia, resolves in a series of experiments with synesthetes, where he brings neurobiology, statistics and genetics into play, with a brief but critical role for imaging technology. Does this sound like a plot for a novel? In some ways it might be. Harrison provides a carefully constructed central argument, a number of fascinating subplots, and if the experiments are less than conclusive—well, such is life, if we wish to portray it accurately. Within the logic of his argument, Harrison exposes potential flaws in prior research, a particular service to nonscientists with an enthusiasm for synesthesia, and reaches some limited but tantalizing conclusions. Highly recommended.