Wednesday, June 07, 2006

The Flight of Colors

If you glance briefly at a high-wattage light bulb or at the sun, then close your eyes, you will experience an enduring afterimage that slowly changes colors. This is called the "flight of colors".

The flight of colors should be relatively easy to study: Just close your eyes and report the colors! The course and variability of the flight of colors might reveal something potentially valuable about the visual system. Yet oddly -- despite the thousands of articles that have been written about other aspects of vision -- almost nothing is known about it.

E.B. Titchener (1901-1905) claims that after staring with dark-adapted eyes at a uniformly colored sky, the flight of colors is blue-green-yellow-red-blue-green -- though it may take a number of trials, and some introspective training, to reliably report that. William Berry (1922 and 1927) argues that there is no consistent pattern in the flight of colors, either between or within stimulus situations. J.L. Brown in his influential 1965 review of the literature on afterimages seems at one point to agree roughly with Titchener's description, then elsewhere, apparently inconsistently, to endorse Berry's claim that the flight of colors varies greatly from person to person. There has been very little subsequent literature on the issue. (For a review see my essay Introspective Training Apprehensively Defended.)

So: Will two normal people in the same circumstances experience roughly the same flight of colors? How much does the flight of colors vary with differences in circumstance? What conditions govern the progression of colors? How can we not know any of this?! Really, it's amazing how fresh and uncut much of psychology still is.

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