stories from the wilder side of science

Skinners Box

Burrhus Frederic Skinner couldn’t have known that the box that he knocked up in the workshop in the Psychology Department at Harvard University would later become one of the most famous pieces of apparatus ever assembled for a scientific experiment. The Skinner box went on to feature in numerous cartoons, and it was parodied in the TV cartoon series The Simpsons. Even a rock band called itself ‘The Skinner Box’. A connection was even drawn between this cage and the supposed suicide of Skinner’s own daughter.

Skinner was 26 years old when he began his search for an instrument that could monitor the behaviour of rats. The maze that was currently popular with researchers (see p. 55) didn’t strike him as ideal. As he later wrote in his memoirs: ‘The animals’ behaviour was composed of too many different “reflexes” and should be taken apart for analysis.’ And so he concentrated on just one small part of the test circuit: a soundproofed box with a noiseless door, from which a rat could be released into a maze without causing disruption. But he soon dropped the maze part of the apparatus altogether.

Using clockwork-like measuring instruments, he tried to determine the animals’ movements. Yet the findings were too haphazard to be properly evaluated. Skinner read Pavlov, who 30 years before had discovered classic conditioning (see p. 63). This technique enabled innate reactions to be linked to new stimuli. However, Skinner didn’t just want to investigate existing reactions but to find out how new behaviours arose.

He finally hit on the idea of equipping his experimentation box with a lever. Whenever the rat pressed down on this, it received a pellet of dried food. Of course, the rat didn’t know this from the outset and only triggered feeding when it happened to touch the lever by accident. But after scoring several such lucky strikes, it appeared to have learned the connection, and consequently the time that elapsed between pushes on the lever became ever shorter. Skinner had thereby discovered a simple yardstick for measuring a rat’s changes in behaviour: namely, the frequency with which a particular behaviour occurred.

Unlike Pavlov’s dogs, the animal in Skinner’s experiment wasn’t exhibiting an innate reaction, but was learning a new behaviour. The theory that Skinner developed on the basis of this comprises three elements: first, living creatures constantly exhibit spontaneous behaviour; second, the consequences of a particular behaviour – positive or negative – diminish or increase the chances that an organism will repeat that behaviour; and third, it is the environment that determines these consequences. He called the whole process ‘operant conditioning’ (to distinguish it from Pavlov’s ‘classical conditioning’).

Skinner had no interest in what went on in the brain in this process. Because it was impossible to directly observe intellectual activity at work, he considered it unscientific to engage with it at all. Together with John B. Watson (see p. 77) he was a leading figure in the movement known as behaviourism, which views animal and human behaviour exclusively as a series of reactions to external stimuli.

The Skinner box had one great advantage over earlier pieces of equipment such as the maze: after the rat had pressed the lever and got the food, everything was then automatically ready for the animal’s next action without any human intervention. An automatic writing device recorded the exact time of each depression of the lever, and from this data Skinnner could study the animal’s learning behaviour under various different conditions. For instance, what happened when the rat had to press down five times in succession before it received a food pellet, or alternatively if it was only rewarded after a random number of depressions? What if it could avoid punishment by carrying out a particular action? And how could a learned behaviour be erased once more? One could almost say that the Skinner box automated research into animal behaviour.

On the face of it, the method behind operant conditioning appears banal – reward reinforces a particular behaviour, while punishment discourages it. Yet Skinner used it to teach animals far more than simply how to press a lever. For example, he taught a pigeon how to play a tune on a toy piano, and two pigeons how to play table tennis. The trick in all this was not to reward the animals only for attaining the overall goal, but for every small interim step. And so the pigeon was given grain when it just happened by chance to hit the correct first note with its beak on the toy piano in the Skinner box – and again when it got the second note right, and the third, and so on until it could play the entire children’s song ‘Over the Fence is Out, Boys’.

Humans could use this kind of training to adapt animal intelligence to a whole variety of tasks. During the Second World War, Skinner worked for the US military on a highly unusual antishipping bomb-guidance system, involving conditioned pigeons placed in the nose cone of the projectile. Depending upon the position of the target ship, which they could see through ports in the nose of the bomb, they would tap with their beaks at different points on a screen. These signals were then used to guide the bomb. This guidance system worked fine in the laboratory, but not in the field.

Skinner didn’t actually coin the term ‘Skinner box’, but it quickly became popular. He was even suspected of having raised his second daughter, Deborah, in a Skinner box, and subsequently a rumour began to do the rounds that Deborah had ended up in a psychiatric institution and taken her own life.

The seeds of this urban myth were sown by the October 1945 edition of the Ladies’ Home Journal. This women’s magazine ran an article on the soundproofed heated crèche that Skinner had built for Deborah. Unfortunately, the title of the piece was ‘Baby in a Box’, which misled many readers into thinking that Deborah had been put in a Skinner box where, like her father’s rats and pigeons, she was forced to take part in experiments. Nowadays Skinner’s daughter, who works as an artist in London, surfaces from time to time in the press to scotch the persistent rumours that she committed suicide.

Skinner was a controversial figure in American academia. His findings were particularly influential in education, since there were clear parallels between his experiments and the way teachers encouraged or rebuked their pupils. As far as Skinner himself was concerned, the world was one great Skinner box, and he was adamant that it could be used to explain the whole gamut of human behaviour. In his controversial book Beyond Freedom and Dignity (1971), he proposed the widespread introduction of conditioning techniques for the good of humankind, as a method of training people to act in ways that were beneficial to society.

from "The Mad Science Book", copyright 2010 Reto U. Schneider