Differential conditioning in the planarian

Abstract

Differential reinforcement of visual and vibratory CSs with a shock UCS showed that a difference in the planarian’s rate of responding to the 2 CSs could be established only when the vibratory CS was positive and the visual CS was negative. In the opposite condition an increase in response rate to both stimuli occurred, but no difference between them was observed. The results appeared to add further support to the proposition that classical conditioning is possible in this organism, but suggested that sensitization and generalization may play a more prominent role in this process than is the case typically.