A goat boxed with a young boy while a raccoon played the piano and two rabbits reenacted a scene from Romeo and Juliet. Though the I.Q. Zoo in Hot Springs, Ark., might have appeared to be a roadside gimmick, it was actually an important study in psychology and animal behavior. Husband-and-wife team Marian and Keller Breland were not circus showrunners, but rather the first-ever applied animal psychologists.
After determining punishment to be an ineffective motivator, even though it was then a common method in animal training, the Brelands focused their training on the provision of rewards for successfully completed tasks. Both had studied under the eminent behavioral psychologist B.F. Skinner, but abandoned graduate study to test the commercial potential of their work. They formed a company, Animal Behavior Enterprises, and later the I.Q. Zoo, to apply principles of human behavior to animals and make an income from that work.
Together, the Brelands appeared on television, traveled to fairs and theme parks, and published an influential article on animal behavior, “The Misbehavior of Organisms.” The paper's title was both a reference and, controversially, a challenge to Skinner’s earlier article, “The Behavior of Organisms.”
Though LIFE introduced them in 1955 as “Psychologist Keller Breland and his wife,” Marian was the one who would go on to a long career, after Keller's was cut short by a fatal heart attack in 1965. She went on finish her Ph.D., become a professor at the University of Arkansas and marry Robert E. Bailey, who had served as the Director of Training for the Navy’s Marine Animal Program and with whom she would continue to train animals and offer workshops.
Different animals at the I.Q. Zoo, which remained open into the 1990s, performed differently under pressure. “Despite apparent stupidity,” LIFE wrote, “chickens are among the easiest creatures to train.” As for the trapeze-swinging hamster, “He occasionally falls but remains undaunted.” But perhaps the hardest worker was the pig, who, after being trained to clean up a messy room, was so eager to please that he tried to drag the photographer’s light stand to the trash.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.