A comparison of shock avoidance learning in headless cockroaches in leg-lifting and lowering task.

Headless cockroaches were trained either to lift or to lower the prothoracic leg to avoid electric shocks. The learning process in both cases was very distinct. However, the learning performance in the lifting was better than in the lowering task. The reason for this poorer learning in the lowering task is due to the unconditioned leg raising movement of the animals to electric shocks. This unconditioned response affects the headless cockroaches avoid shocks in the lifting task by escape learning, whereas they avoid shocks in the lowering task by true avoidance learning. Injection of 30 microliter of Ringer's solution has no significant effect on the learning process in the lifting task. In the lowering task, however, Ringer's solution impairs the learning ability considerably. Crude extract of corpora cardiaca strongly inhibits the learning of both tasks.