Monday, 11 June 2012
The Phi Effect Is Not the Beta Effect!
Science is not immune to historic errors that can be passed along for decades. One such error was the confusion of the phi effect with the beta effect, which persisted until Robert M. Steinman and his colleagues published their clarification in 2000.
The phi effect was first described in Experimental Studies on the Seeing of Motion, a book published in 1912 by Max Wertheimer, one of the fathers of Gestalt psychology. The problem was that in his book, Wertheimer did not describe the conditions for the appearance of the phi effect precisely. He said that this phenomenon occurs when two lines are projected on a screen in very close chronological succession, thus creating the impression (under certain observation conditions that he left undefined) that a fuzzily defined area the same colour as the background is moving between these two lines. (more…)