The role of contextual and sporadic stimuli in escape conditioning in dogs.

Instrumental escape bar-pressing responses were rapidly acquired in four male dogs and showed great resistance despite a long pause in experimental sessions. More intertrial responses were performed after short- than after long-latency escape responses. In the next stage of the experiment shock trials were discontinued and on the defensive context novel accoustical stimuli were introduced. The auditory stimuli provoked instrumental bar-press responses that were somewhat dependent on the intensity of stimuli.