Acquired equivalence learning with antecedent and consequent unconditioned stimuli.

The conditions under which cues with similar training histories are treated by rats as being equivalent were examined. A significant event, food, either preceded, followed, or preceded and followed each of the Stimuli A and B; Stimulus C was not food-associated. Next, B was counterconditioned with footshock until it suppressed an appetitively motivated behavior. When A and C were tested for generalized suppression, A (treated like B) evoked more suppression than C (treated differently than B). However, this equivalence effect was strong only when A and B predicted food and were treated alike.