Human beings were not created for the convenience of experimental
psychologists.

-- George Miller ¹

According to a common stereotype, a science develops in a logical and
organized manner: Although different scientists study different phenomena
within the science, they use a common methodology to explore them.
Although different scientists develop different aspects of theory, they con-
tribute pieces to a single developing theory. Although new discoveries
continually appear, each builds upon previous discoveries systematically and
coherently. As a science evolves, each new piece of the puzzle falls into place.

Unfortunately, this scientific fairy tale is more fiction than fact, especially
in cognitive psychology. Clearly, some sciences are more stable than others,
but even physics, which is perhaps the most stable, contains controversies
and different approaches. Philosophers of science often observe that revolu-
tion in science is no less common than cumulative evolution ( Kuhn, 1970; see
also Bechtel, 1988b, McCauley, 1986). Controversy is particularly extensive
in young sciences, as researchers struggle to find an approach that works.
Unfortunately, the leaders of a new science typically don't know a method-
ology that will produce systematic and coherent accumulation, nor can they

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