The Law of Effect in Psychology

Cat in box
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The law of effect principle developed by Edward Thorndike suggested that responses closely followed by satisfaction will become firmly attached to the situation and therefore more likely to reoccur when the situation is repeated.

Conversely, if the situation is followed by discomfort, the connections to the situation will become weaker, and the behavior of response is less likely to occur when the situation is repeated.

Imagine that you arrive early to work one day by accident. Your boss notices and praises your diligence. The praise makes you feel good, so it reinforces the behavior.

You start showing up for work a little bit early each day to keep receiving your boss’s commendations. Because a pleasing consequence followed the behavior, the action became more likely to be repeated in the future.

More Examples

  • If you study and then get a good grade on a test, you will be more likely to study for the next exam.
  • If you work hard and then receive a promotion and pay raise, you will be more likely to continue to put in more effort at work.
  • If you run a red light and then get a traffic ticket, you will be less likely to disobey traffic lights in the future.


While we often associate the idea that consequences lead to changes in behavior with the process of operant conditioning and B.F. Skinner, this notion has its roots in the early work of psychologist Edward Thorndike.

In his experiments, Thorndike utilized what is known as puzzle boxes to study how animals learn.

The boxes were enclosed but contained a small lever that, when pressed, would allow the animal to escape. Thorndike would place a cat inside the puzzle box and then place a piece of meat outside the box.

He would then observe the animal’s efforts to escape and obtain the food. He recorded how long each animal took to figure out how to free itself from the box.

Eventually, the cats would press the lever, and the door would open so that the animal could receive the reward. Even though first pressing the lever occurred simply by accident, the cats became likely to repeat it because they had received an award immediately after performing the action.

Thorndike noted that with each trial, the cats became much faster at opening the door. Because pressing the lever had led to a favorable outcome, the cats were much more likely to perform the behavior again in the future.

Thorndike termed this the “Law of Effect,” which suggested that when satisfaction follows an association, it is more likely to be repeated. If an unfavorable outcome follows an action, then it becomes less likely to be repeated.

There are two key aspects of the law of effect:

  • Behaviors immediately followed by favorable consequences are more likely to occur again. In our earlier example, being praised by a supervisor for showing up early for work made it more likely that the behavior would be repeated.
  • Behaviors followed by unfavorable consequences are less likely to occur again. If you show up late for work and miss an important meeting, you will probably be less likely to show up late again in the future. Because you view the missed meeting as a negative outcome, the behavior is less likely to be repeated.

Influence on Behaviorism

Thorndike’s discovery had a major influence on the development of behaviorism. B.F. Skinner based his theory of operant conditioning on the law of effect. Skinner even developed his own version of a puzzle box which he referred to as an operant conditioning chamber (also known as a Skinner box).

In operant conditioning, behaviors that are reinforced are strengthened, while those that are punished are weakened. The law of effect clearly had a major influence on the development of behaviorism, which went on to become the dominant school of thought in psychology for much of the 20th century.​

Many behavioral principles remain in use today. In therapeutic settings, psychologists and other mental health professionals often use reinforcement to encourage positive behaviors and discourage undesirable ones. In such cases, the use of favorable outcomes may be used to increase the likelihood of future positive behaviors.

Thorndike's research on the laws of learning played an important role in the development of behavioral psychology and continues to exert influence to this day.

4 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Thorndike E. Animal intelligence: An experimental study of the associative processes in animalsThe Psychological Review: Monograph Supplements. 1898;2(4):i-109. doi:10.1037/h0092987

  2. Huang J, Ruan X, Yu N, Fan Q, Li J, Cai J. A cognitive model based on neuromodulated plasticity. Comput Intell Neurosci. 2016;2016:4296356. doi:10.1155%2F2016%2F4296356

  3. B.F. Skinner Foundation. Biographical information.

  4. Behaviorism. Stanford Encyclopedia of Philosophy. Revised March 19, 2019.

By Kendra Cherry, MSEd
Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."