Psychology › Learning & behavior › Operant conditioning
Thorndike's law of effect
1898· Theory or model
Well replicatedStrong, repeated evidence.
Edward Thorndike's rule that actions followed by satisfying results are repeated, and those followed by discomfort fade.
See it on the Psychology map →What it says
For his 1898 Columbia dissertation, Thorndike (1874–1949) put hungry cats in 'puzzle boxes' that opened when they pulled a loop or pressed a lever. At first they escaped by chance. Over repeated trials useless moves dropped out and escape times fell, gradually rather than in a sudden flash of insight. In 1911 he stated the law of effect: responses followed by satisfaction become more firmly connected to the situation. He went on to apply learning research to schools and testing.
Why it matters
It was the first experimental law of learning and the direct ancestor of Skinner's operant conditioning, tying behavior to its consequences.
The evidence
Status: well replicated. His learning curves, published in 1898 and 1911, have been reproduced across many species. In the 1930s he weakened the punishment half himself after finding it had less effect than reward.
Open questions
Whether animals learn only by trial and error: Wolfgang Köhler's chimpanzees (1917) seemed to solve problems by sudden insight, a debate that continues.
Connections (2)
▸Thorndike's law of effect laid the groundwork for Operant conditioningWell replicated
The connection
Thorndike's cats escaping puzzle boxes showed actions are 'stamped in' by satisfying results. Skinner took the same principle and made it precise: instead of timing single escapes, his chamber let an animal respond freely while every response was counted, revealing how the rate of behavior tracks its consequences.
Who showed it and when
Thorndike at Harvard and Columbia, 1896–1911; Skinner at Harvard from 1928, publishing his system in 1938.
The evidence
Skinner credited the law of effect in his own writings, and historians routinely trace operant conditioning back to Thorndike's puzzle boxes.
Open questions
How much Skinner added beyond Thorndike: some see a new science of response rates, others mainly better tools and a new vocabulary.
▸Thorndike's law of effect stated the principle behind Reinforcement and punishmentWell replicated
The connection
Thorndike's law of effect is the core idea of reinforcement: a satisfying result strengthens the link between a situation and the action that produced it, and an 'annoying' one weakens it, the original version of punishment. Later behaviorists replaced his words 'satisfaction' and 'annoyance' with neutral terms defined only by their effect on behavior.
Who showed it and when
Columbia University, New York: his 1898 dissertation, his 1911 book Animal Intelligence, then experiments with human learners around 1930.
The evidence
Thorndike's published learning curves, and textbooks that cite the law of effect as the origin of reinforcement theory.
Open questions
By the 1930s Thorndike concluded punishment weakens behavior far less than reward strengthens it; how symmetrical the two really are is still argued.