Development of a complex multiple schedule in the chimpanzee

The development of chimpanzee behavior on a four-component, three-lever multiple schedule is described. Component schedules included the Sidman avoidance procedure with a concurrent discriminated avoidance schedule on a second lever, fixed ratio performance for food, differential reinforcement of low rate for water requiring a dual response chain, and a symbol discrimination task for continuous food reinforcement using three levers. The avoidance component of this schedule was employed during the January 31, 1961 suborbital space flight of the chimpanzee “Ham.” On November 29, 1961, the chimpanzee “Enos” performed on the multiple schedule during three orbits around the earth in a Mercury capsule.