Behaviorism: What It Is and Where It Came From

A manifesto published in 1913

In 1913 the American psychologist John B. Watson published, in the journal Psychological Review, the essay that started the movement: he proposed turning psychology into an experimental science on a par with the other natural sciences, with a precise object of study, observable behavior. The goal he set was not to describe consciousness, but to predict and control behavior.

To get there, Watson set introspection aside, the account a person gives of their own thoughts or sensations. It isn’t that behaviorists denied people have thoughts: it’s that those reports, in Watson’s view, didn’t hold up as scientific data, because two different laboratories couldn’t reach the same results starting from the same introspective reports. A science needs measurements that anyone, in any laboratory, can reproduce.

Watson’s program is also broader than it looks at first glance: it draws no sharp line between human and animal behavior. The same model that explains why a rat presses a lever explains, for him, why a person reacts to a situation, you look at what precedes the behavior, the stimulus, and what follows it, the response, not at what happens inside the head of the person doing it.

The stimulus-response model, with an example

Practical example: a dog hears the sound of a bell every time it gets food. After a few repetitions, the dog salivates at the mere sound of the bell, even when no food is coming. The bell, on its own, has become capable of producing the response that only the food used to produce: that’s the stimulus-response model at work, and it’s the experiment through which Ivan Pavlov enters the history of behaviorism.

Pavlov, born in 1849 and died in 1936, didn’t call himself a behaviorist: he was a Russian physiologist, and he studied reflexes. His way of working, measuring an observable response to a controlled stimulus, with no need to know what the dog “thinks,” is the method behaviorism adopts as its own.

Working alongside Pavlov was Edward Thorndike, born in 1874 and died in 1949. Thorndike studied how animals learn through trial and error: an animal tries different actions until it finds the one that works, and repeats it more and more often. From this comes his law of effect: a behavior followed by a satisfying outcome tends to repeat; one followed by an unpleasant outcome tends to fade away.

Skinner and radical behaviorism

Burrhus Skinner pushed Watson’s program to a more extreme point, one he himself called radical behaviorism. Where Watson’s behaviorism sets thoughts aside because they can’t be measured in a laboratory, Skinner’s extends the same treatment to inner physiological processes too: for predicting and controlling behavior, they aren’t needed.

Skinner describes learning through operant conditioning: a behavior, an operant, that is followed by reinforcement grows more frequent. A behavior that’s ignored or punished, instead, fades.

The difference between the two versions of behaviorism isn’t about what exists, but about what counts for science.

A legacy beyond the animal lab

Behaviorism’s ideas didn’t stay confined to rats in cages and dogs with bells. The stimulus-response model and the focus on observable behavior, rather than on inner explanations, shaped how learning and education were studied for decades, and reach into how we look at human emotions as well: not to deny them, but to ask what, about an emotion, can be observed and measured from the outside.