The Effects of Feature Identity in Operant Serial Feature-Negative Discriminations

The effects of feature identity in an operant serial feature-negative discrimination (F1 T1−, T1+) were examined in two experiments with rats. In Experiment 1, rats were trained with two operant serial feature-negative discriminations in which different operants were reinforced during two auditory target cues (T1 and T2). The features (F1 and F2) were two neutral cues (visual or auditory stimuli), two motivationally significant cues (flavored sucrose solutions, also used as the operant reinforcers), or one neutral and one motivationally significant cue. Experiment 1 showed that discrimination acquisition, transfer performance, and feature–target interval testing were facilitated with a flavored sucrose feature. Experiment 2 showed that flavored sucrose-alone presentations, more than flavored sucrose trained in a pseudodiscrimination (F1 T1+, T1+), shared several similarities with a standard flavored sucrose feature. The results suggest flavored sucrose rapidly acquires inhibitory properties, which facilitates operant serial feature-negative discrimination performance.