Putative inhibitory training of a stimulus makes it a facilitator: a within-subject comparison of visual and auditory...

Pigeons were trained with the A+, AB-, ABC+, AD- and ADE+ task where each of stimulus A and stimulus compounds ABC and ADE signalled food (positive trials), and each of stimulus compounds AB and AD signalled no food (negative trials). Stimuli A, B, C and E were small visual figures localised on a response key, and stimulus D was a white noise. Stimulus B was more effective than D as an inhibitor of responding to A during the training. After the birds learned to respond exclusively on the positive trials, effects of B and D on responding to C and E, respectively, were tested by comparing C, BC, E and DE trials. Stimulus B continuously facilitated responding to C on the BC test trials, but D's facilitative effect was observed only on the first DE test trial. Stimulus B also facilitated responding to E on BE test trials. Implications for the Rescorla-Wagner elemental model and the Pearce configural model of Pavlovian conditioning were discussed.