The Skinner Box or Operant Conditioning Chamber

Pigeons in a Skinner box

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A Skinner box, also known as an operant conditioning chamber, is an enclosed apparatus that contains a bar or key that an animal can press or manipulate in order to obtain food or water as a type of reinforcement. Developed by B. F. Skinner, this box also had a device that recorded each response provided by the animal as well as the unique schedule of reinforcement that the animal was assigned.

Skinner was inspired to create his operant conditioning chamber as an extension of the puzzle boxes that Edward Thorndike famously used in his research on the law of effect. Skinner himself did not refer to this device as a Skinner box, instead preferring the term "lever box."

How a Skinner Box Works

So how exactly do psychologists and other researchers use a Skinner box when conducting research? The design of Skinner boxes can vary depending upon the type of animal and the experimental variables. The box must include at least one lever, bar, or key that the animal can manipulate.

When the lever is pressed, food, water, or some other type of reinforcement might be dispensed. Other stimuli can also be presented, including lights, sounds, and images. In some instances, the floor of the chamber may be electrified.

Using the device, researchers can carefully study behavior in a very controlled environment. For example, researchers could use the Skinner box to determine which schedule of reinforcement led to the highest rate of response in the study subjects.

The Skinner Box in Research

For example, imagine that a researcher wants to determine which schedule of reinforcement will lead to the highest response rates. Pigeons are placed in chambers where they receive a food pellet for pecking at a response key. Some pigeons receive a pellet for every response (continuous reinforcement).

Partial Reinforcement Schedules

Other pigeons obtain a pellet only after a certain amount of time or number of responses have occurred (partial reinforcement). There are several types of partial reinforcement schedules.

  • Fixed-ratio schedule: Pigeons receive a pellet after they peck at the key a certain number of times; for example, they would receive a pellet after every five pecks.
  • Variable-ratio schedule: Subjects receive reinforcement after a random number of responses.
  • Fixed-interval schedule: Subjects are given a pellet after a designated period of time has elapsed; for example, every 10 minutes.
  • Variable-interval schedule: Subjects receive a pellet at random intervals of time.

Once the data has been obtained from the trials in the Skinner boxes, researchers can then look at the rate of responding. This will tell them which schedules led to the highest and most consistent level of responses.

The Baby Tender

The Skinner box should not be confused with one of Skinner's other inventions, the baby tender. At his wife's request, Skinner created a heated crib with a plexiglass window that was designed to be safer than other cribs available at that time. Confusion over the use of the crib led to it being confused with an experimental device, which led some to believe that Skinner's crib was actually a variation of the Skinner box.

At one point, a rumor spread that Skinner had used the crib in experiments with his daughter, leading to her eventual suicide. The Skinner box and the baby tender crib were two different things entirely, and Skinner did not conduct experiments on his daughter or with the crib. Nor did his daughter take her own life. 

The Skinner box became an important tool for studying learned behavior. It contributed a great deal to our understanding of the effects of reinforcement and punishment.

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  1. Operant conditioning chamber. In: APA Dictionary of Psychology. American Psychological Association.

  2. B.F. Skinner Foundation. Biographical information.

  3. Schacter DL, Gilbert DT, Wegner DM. Psychology. 2nd edition. Worth, Inc., 2011.