A group of 8 pigeons is lesioned in the hyperstriatum, a structure thought to be critically involved in learning. A control group of 8 pigeons receive sham operations. Two of the lesioned birds and one of the control birds subsequently die. After the remaining birds have fully recovered and are willing to eat normally from the feeder of a Skinner box they are subjected to an autoshaping procedure, the number of key-pecks emitted by each bird in a one-hour session being recorded. A high number of key pecks indicates good learning.