ABSTRACT
Are species differences in learning attributable to the evolutionary divergence of learning mechanisms? Are species similarities understandable in terms of the evolutionary homology or homoplasy of learning mechanisms? These questions are not easy to answer. The difficulties raised by the comparative analysis of learning have inspired many ingenious procedures and approaches that provide convergent evidence on specific research phenomena. Complex testing procedures and experimental designs are used to distinguish learning from a variety of other processes that can also affect behavior. Brain-behavior, ecology-behavior, and ecology-brain-behavior correlations have also been used as a source of comparative information. Let us begin with a careful consideration of methodological problems.
