A test between the selective attention and stimulus generalization interpretations of the easy-to-hard effect

The selective attention and stimulus generalization interpretations of the easy-to-hard effect were tested by training one group of rats on an easy brightness discrimination and “reversing” them on a more difficult brightness discrimination. A control group, initially trained on the difficult discrimination, was reversed at the same time as the experimental group. The experimental group learned the reversal more rapidly and this was interpreted as supporting the selective attention interpretation.