Behaviourism · 1911
Law of effect
Behaviour is strengthened or weakened according to the effects it produces: consequences teach what will be repeated.
The Law of effect, formulated by Edward L. Thorndike on the basis of his animal experiments in the so-called puzzle boxes, is one of the founding pillars of instrumental learning. Thorndike observed that responses followed by satisfying consequences tend to be strengthened and repeated, whereas those followed by unsatisfying consequences decrease in their probability of occurrence. This principle introduces the notion of trial-and-error learning and displaces mentalistic explanations in favour of an empirical analysis of the relationship between behaviour and consequences. Although it is not a psychotherapeutic model, the Law of effect establishes the conceptual basis of operant reinforcement and guides the later development of applied behavioural psychology, with a decisive influence on education, behaviour modification and behavioural psychotherapy.
Core ideas
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Consequences select behaviour
The Law of effect establishes that it is not intentions or thoughts that determine which behaviours persist, but the consequences that follow the action. Reference: Thorndike (1911).
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Learning is gradual and cumulative
Behavioural change occurs progressively through trial and error, with no need for sudden comprehension of the problem. Reference: Thorndike (1911).
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Reinforcement increases future probability
Responses followed by satisfying consequences tend to be repeated, anticipating the modern concept of positive reinforcement. Reference: Thorndike (1932).
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Behaviour can be studied scientifically
The use of animals and experimental apparatus demonstrates that learning can be analysed with quantitative, replicable methods. Reference: Thorndike (1911).
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Psychology must rest on observable data
The Law of effect reinforces the empiricist turn towards objective measurement as the basis of psychological knowledge. Reference: Thorndike (1911).
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Consequences matter more than intentions
The model shifts psychological explanation from will or insight towards the real effects of behaviour in the environment. Reference: Thorndike (1932).
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It is a pillar of later behaviourism
The Law of effect is the direct antecedent of Skinner's operant conditioning and of applied behavioural intervention. Reference: Skinner (1938).
Influences
- Animal psychology
- Instrumental learning
- Comparative psychology
- Objectivist empiricism / Logical positivism
Key references
- Thorndike, E. L. (1911). Animal Intelligence: Experimental Studies.
- Thorndike, E. L. (1932). The Fundamentals of Learning.
- Skinner, B. F. (1938). The Behavior of Organisms.