What is a Skinner box?

Introduction

The modern Skinner box consists of a chamber housed in a sound- and light-attenuating shell and connected to a computer through an interface. This arrangement ensures a uniform, controlled environment that minimizes extraneous and distracting stimuli during an experiment. For rats and mice, the chamber is usually equipped with one or more manipulanda (for example, a lever to be pressed or a chain to be pulled). Responses are detected electronically (through closure of a microswitch) and recorded by computer software. The rodent chamber typically has a device that dispenses food (for example, 20- or 45-milligram pellets) or a liquid (for example, water or sugar solutions) into a magazine tray located near the manipulanda, and is equipped with speakers (to present auditory stimuli) and lights. Presentations of these events are programmed using computer software. Operant chambers for rodents are manufactured with grid floors that can be set up for delivery of faradic stimulation (electric shock) for use in Pavlovian studies of fear conditioning and instrumental studies of punishment or escape and avoidance learning.

Operant chambers for pigeons generally have either a projector to display visual stimuli on a response key that is pecked by the pigeon or an LCD panel for displaying computer-generated images, and a hopper to present grain that can be accessed through an opening in the magazine tray. Head entries into the magazine tray to retrieve a reward can be detected automatically by interruption of a photobeam. Operant chambers may be modified for use with small primates.

The operant chamber is typically used for the study of changes in behavior as a result of its consequences.

History

The Skinner box was one of many inventions created by the radical behaviorist B. F. Skinner. While a graduate student in psychology at Harvard, Skinner began experiments to understand the variability of behavior and to investigate the conditions that affected the strength of behavior. He constructed an experimental chamber with a feeding device that registered a rat’s contacts as it retrieved measured quantities of food. Later, Skinner equipped his box with a horizontal bar that, when pushed down by the rat, would cause a feeder to dispense a pellet into the magazine tray. In The Behavior of Organisms (1938), Skinner devotes three pages to a discussion of his use of the lever press response as an operant. The typical lever was a 1/8-inch brass rod, 6 centimeters (cm) long, mounted 8 to 10 cm above the floor and protruding 1 cm into the chamber. The rat had to exert about 10 grams of pressure to depress the lever and register a response on a cumulative recorder. Among the merits of the lever press response mentioned by Skinner were the ease and spontaneous frequency with which the response was made by rats. Another advantage he noted was that this operant required stimulus support and therefore could not occur in the absence of the actual lever.

Throughout the 1930s, Skinner used an operant chamber fitted with a lever for rats. Following his work on Project Pigeon in the early 1940s, Skinner constructed a modified operant chamber for pigeons and in subsequent work used pecking at a response key as the operant. The pigeon’s superior vision and longer life contributed to his decision to switch organisms.

Impact on Research

The Skinner box provided researchers in the 1930s with a laboratotry apparatus that had several highly desirable advantages over mazes and runways. Data collection was substantially less labor- and time-intensive. Larger numbers of animals could be studied, which increased the power of statistical analysis and the likelihood of detecting lawful properties of behavior by averaging across individuals. The cumulative recorder, another of Skinner’s ingenious inventions, provided an immediate and continuous record of the rate of behavior (a measure of its strength) that could be mechanically averaged across subjects by the Summarizer, also developed by Skinner.

In addition to these practical benefits, there were significant theoretical impacts of the new apparatus. Arguably the most important was the distinction Skinner was prompted to make on the basis of his studies with the operant chamber between two kinds of responses, respondent (Pavlovian) and operant (instrumental). Whereas respondents were elicited by preceding stimuli, operants were controlled by their consequences (the reinforcement contingency).

Shaping by successive approximation was a technique developed by Skinner to train animals to perform complex actions. The operant chamber also allowed him to develop his theory of how schedules of reinforcement influenced behavior in lawful ways. It is no accident that slot machines use a variable ratio schedule of reinforcement.

Contemporary psychology reflects the impact of the modern operant chamber in many ways. Empirical challenges to classical temporal contiguity theory (for example, blocking and contingency) emerged from studies using changes in the rate of a free operant to assess learning. Postconditioning manipulations of a response-contingent outcome have illuminated the processes involved in instrumental learning. Behavior modification programs use the principles of operant conditioning.

Effects of Skinner’s work with the operant chamber have extended beyond psychology to behavioral economics, behavioral pharmacology, and personalized instruction. Skinner did not raise his daughter Deborah in an operant chamber, contrary to urban legend, but he did build the baby tender, which was designed to provide a safe and comfortable environment for an infant. Skinner’s Walden Two (1948) describes a fictional utopian community that raised its children using the principles of operant conditioning.

Bibliography

Ferster, Charles B. “The Use of the Free Operant in the Analysis of Behavior.” Psychological Bulletin 50.4 (1953): 263–74. Print.

Lattal, Kennon A. “JEAB at 50: Coevolution of Research and Technology.” Journal of the Experimental Analysis of Behavior 89.1 (2008): 129–35. Print.

O’Donohue, William, and Kyle E. Ferguson. The Psychology of B. F. Skinner. Thousand Oaks: Sage, 2001. Print.

Rutherford, Alexandra. Beyond the Box: B. F. Skinner's Technology of Behavior from Laboratory to Life, 1950s–1970s. Toronto: U of Toronto P, 2009. Print.

Schachter, Daniel L., Daniel T. Gilbert, and Daniel M. Wegner. “B. F. Skinner: The Role of Reinforcement and Punishment.” Psychology. 3rd ed. New York: Worth, 2014. 278–80. Print.

Vargas, Julie. “Biographical Information.” B. F. Skinner Foundation. B. F. Skinner Foundation, n.d. Web. 25 June 2014.