At the same time, the author conducted a set of experiments designed to determine if electric field exposure was aversive to baboons. If field exposure was painful or uncomfortable, the resulting stress could lead, indirectly, to adverse consequences. The baboons were trained that pushing a button would turn off the electric field and produce a food reward. The six baboons responded well. The large size of the baboon, relative to that of the rat, makes it a much better model of the human.
Operant behavior refers to animals responding, typically by pushing a button, to earn food rewards.
The first two series of experiments involved use of operant methods. The subjects did not push buttons for the first few hours of exposure. Once they resumed responding, they functioned normally. The sudden introduction of an unusual stimulus, at a level 2.5 or 5.0 times its detection threshold, can temporarily interfere with operant responding. That is why most operant experiments are done in a Skinner box, an enclosure that isolates the subject from irrelevant cues in the external environment.