A passive operant-avoidance procedure was employed to condition 12 bullfrogs and 6 grass frogs to inhibit the righting-reflex. To avoid an electric shock of .8 mA, both species, when flipped, remained frozen rather than showing the short-latency righting-reflex; 6 toads failed to show passive-avoidance learning. The data are considered within the context of species-specific behavior and tonic immobility.
Species-specific defense reactions in escape-from-fear situations
