Keller and Marian trained a wide variety of animals, experimenting with shaping behavior using reinforcement. In Marian Breland Bailey's unpublished memoir, "The Animal Company", she wrote of early experimentation with training cockroaches while working with B. F. Skinner on the "Pigeon in a Pelican" (the nickname given to the missile) project for the United States Navy during 1942 in Minneapolis, Minnesota:
"During one lull [in the pigeon project, working with Skinner for the United States Navy] while we were waiting for word from Washington, work with the birds had been virtually suspended, and we had time on our hands. It was during this interlude that Keller [Breland], Bill [Estes], and Norman [Guttman] decided to train some of the numerous large and vigorous cockroaches that shared the building with us.
What do you use to reward a cockroach? Of course they eat, but handling with ease the tiny amount of food necessary to reinforce even a large cockroach presents some technical problems. So, observing that cockroaches prefer the dark and shun the light, they rigged up a tiny lever, attached with fine wire to a light switch, in such a way that when the cockroach pressed the lever, the light went out. Thus the cockroach learned to do with regularity and assurance, thus extending the laws of operant behavior to the world of Arthropods." Excerpt from "The Animal Company" (unpublished memoir) by Marian Breland Bailey, ca. 1980
Unlike the majority of animal trainers, the staff at ABE used positive reinforcement rather than punishment in behavior shaping. ABE training principles were based on working with and understanding the natural instincts and emotions of an animal, while using reinforcement to shape new behaviors.
Some people questioned the care and treatment of the animals trained and used in acts. ABE was very careful and descriptive in the acts' manuals about the amount of food, exercise, and attention each animal received.