An extension of Klahr and Dunbar's (1988) Dual space model
of scientific discovery is presented. W e propose that, in
addition to search in an experiment space and a hypothesis
space, scientific discovery involves search in two additional
spaces; the space of data representations and the space of
experimental paradigms. That is, discoveries often involve
developing new terms and adding new features to descriptions
of the data, and the also often involve developing new kinds
of experimental procedures. The 4-space model was
motivated by the analysis of human performance in a
discovery microworld. A brief description of the data is
presented. In addition to the general 4-space framework, a
description of the component processes involved in each of
the four search spaces is also presented
