Contextual control of Pavlovian bidirectional occasion setting.

Three pigeons were trained in a lighted context on a bidirectional occasion-setting task in which a tone feature (F) signaled food after the green keylight (L:G-, L:FG+) and no food after the red keylight (L:R+, L:FR-). They acquired the former feature-positive (F-P) discrimination and the latter feature-negative (F-N) discrimination at almost equal speed. Another three birds were trained with a F-P discrimination task in a light context (L:G-, L:FG+) and with a F-N discrimination task in a dark context (D:G+, D:FG-). The keylight was always green and two contextual conditions were changed randomly trial by trial. In this training, the F-P discrimination was acquired faster than the F-N discrimination. Then, all birds received a more complex amalgam contingency in which all eight types of trials were presented in the session (D:R-, D:G+, D:FR+, D:FG-, L:R+, L:G-, L:FR-, L:FG+). After they learned the amalgam training, the outcomes of two trial types were changed (D:R+, D:G-), but this treatment failed to reverse the pattern of responding in the remaining trial types.