This study investigated subjects’ ability to make discriminations within the target and distractor sets following consistent mapping training in a visual search task. Differences in the patterns of reaction time data obtained with and without the requirements to make discriminations within target and distractor sets suggest that automatic processing entails two processing changes. One change involves treating the target set as a single equivalence class. This increases efficiency of the memory comparison process. A second change involves inhibition or filtering of distractor elements, which increases the efficiency of visual search.