Law of Effect in AP Psychology

In AP Psychology, the Law of Effect is Edward Thorndike's principle that behaviors followed by satisfying (reinforcing) consequences become more likely to be repeated, while behaviors followed by discomfort (punishing consequences) become less likely. It is the foundation of operant conditioning (Topic 3.8).

What is the Law of Effect?

The Law of Effect is Edward Thorndike's rule for how consequences shape behavior. If a response in a situation is followed by something satisfying, the link between that situation and that response gets stronger. The next time you're in the same situation, you're more likely to do it again. If the response is followed by discomfort, the link gets weaker, and the behavior becomes less likely.

Think of it as "consequences steer behavior" in its simplest form. The AP Psych CED states it directly in Topic 3.8: behaviors with reinforcing consequences are more likely to be repeated, while behaviors with punishing consequences are not as likely to be repeated. Thorndike gave psychology the basic idea. B.F. Skinner later built it out into the full system of operant conditioning, with positive and negative reinforcement, punishment, and reinforcement schedules.

Why the Law of Effect matters in AP® Psychology

The Law of Effect lives in Unit 3: Development and Learning, under Topic 3.8 Operant Conditioning. It supports learning objective AP Psych 3.8.A, which asks you to explain how operant conditioning applies to behavior and mental processes. The CED's essential knowledge for 3.8.A names the Law of Effect explicitly as the core rule of operant learning, so it's the starting point for everything else in the topic. Reinforcement, punishment, shaping, and schedules of reinforcement all assume the Law of Effect is true. If you understand that consequences change the odds of a behavior happening again, the rest of 3.8 clicks into place. For the full topic breakdown, head to the 3.8 Operant Conditioning study guide.

How the Law of Effect connects across the course

Reinforcement and Punishment (Unit 3)

Reinforcement and punishment are the Law of Effect split into its two halves. "Satisfying consequence" became reinforcement, which increases a behavior. "Discomfort" became punishment, which decreases it. Skinner then added the positive (add something) and negative (take something away) versions, but the logic is still Thorndike's.

B.F. Skinner and Operant Behavior (Unit 3)

Thorndike stated the rule, and Skinner turned it into a science. Skinner studied operant behavior, meaning behavior that operates on the environment and produces consequences. He measured how different consequences and reinforcement schedules (like a fixed-ratio schedule) change response rates. If Thorndike drew the sketch, Skinner did the full blueprint.

Shaping and Superstitious Behavior (Unit 3)

Shaping uses the Law of Effect on purpose. You reward successive approximations, like a piano teacher rewarding single notes, then phrases, then whole sections. Superstitious behavior is the Law of Effect by accident. A runner wins while wearing a bracelet, the win feels like a reward, and now she keeps wearing it even though the bracelet caused nothing.

Cognitive and Biological Limits on Learning (Unit 3)

The Law of Effect explains a lot, but not everything. Cognitive psychologists argue that consequences alone can't account for thinking, expectations, and learning that happens without immediate reward. Instinctive drift shows that biology can override reinforcement too. Learned helplessness shows that when consequences feel uncontrollable, organisms stop trying altogether.

Is the Law of Effect on the AP® Psychology exam?

The Law of Effect usually shows up in multiple-choice scenarios, not as a bare definition. You'll get a short story about a person, kid, or animal, and you'll need to predict what happens to a behavior based on its consequences. Common stem types include:

• Predicting what reduces a behavior. A question might ask which response would be LEAST effective in reducing a child's public tantrums. The Law of Effect says anything that rewards the tantrum (giving in, giving attention, handing over candy) will make it more likely, so that's your answer.
• Spotting accidental reinforcement. A runner keeps wearing a "lucky" bracelet after a win. That's superstitious behavior, which is a behavior strengthened by a coincidental reward.
• Recognizing shaping. Rewarding small steps toward a complex skill is the Law of Effect applied gradually.
• Critiquing the theory. Some questions ask what operant conditioning fails to explain, which points to cognitive processes like thinking and expectations.

No released FRQ has used the term "Law of Effect" verbatim. On an FRQ, though, you may need to explain why a behavior increased or decreased. That's exactly what the Law of Effect does. Name the consequence, label it reinforcing or punishing, and state the effect on future behavior.

The Law of Effect vs Operant conditioning (B.F. Skinner)

These are related but not identical. The Law of Effect is Thorndike's single principle. Satisfying consequences strengthen a behavior, and uncomfortable ones weaken it. Operant conditioning is the broader learning theory Skinner built on top of that principle. It adds positive and negative reinforcement, positive and negative punishment, primary and secondary reinforcers, shaping, and reinforcement schedules. If a question names Thorndike or asks for the basic rule that consequences change behavior, think Law of Effect. If it asks about schedules, Skinner boxes, or specific reinforcement types, think operant conditioning.

Key things to remember about the Law of Effect

• The Law of Effect, proposed by Edward Thorndike, states that behaviors followed by satisfying consequences are more likely to be repeated and behaviors followed by discomfort are less likely to be repeated.

• The Law of Effect is the foundation of operant conditioning in Topic 3.8 and appears directly in the essential knowledge for learning objective AP Psych 3.8.A.

• Reinforcement is the half of the Law of Effect that strengthens behavior, and punishment is the half that weakens it.

• B.F. Skinner expanded Thorndike's idea into operant conditioning by studying specific types of reinforcement and punishment and how reinforcement schedules affect behavior.

• Shaping applies the Law of Effect intentionally by rewarding small steps, while superstitious behavior happens when a behavior is accidentally strengthened by a coincidental reward.

• On the exam, you'll usually apply the Law of Effect to a scenario by identifying the consequence and predicting whether the behavior will increase or decrease.

Frequently asked questions about the Law of Effect

What is the Law of Effect in AP Psychology?

The Law of Effect is Edward Thorndike's principle that behaviors followed by satisfying consequences become more likely to happen again, while behaviors followed by discomfort become less likely. It falls under Topic 3.8 Operant Conditioning in Unit 3.

Did B.F. Skinner come up with the Law of Effect?

No. Edward Thorndike proposed the Law of Effect. Skinner built on it later, developing operant conditioning with detailed concepts like positive and negative reinforcement and reinforcement schedules.

How is the Law of Effect different from operant conditioning?

The Law of Effect is the core principle that consequences change how likely a behavior is. Operant conditioning is the full learning theory built on that principle, including reinforcement types, punishment types, shaping, and schedules like the fixed-ratio schedule.

Does giving a child attention during a tantrum stop the tantrum?

Usually not, and it often does the opposite. Under the Law of Effect, attention can act as a satisfying consequence that reinforces the tantrum and makes future tantrums more likely, which is why giving in is the least effective way to reduce them.

Is the Law of Effect on the AP Psychology exam?

Yes. The CED names it in the essential knowledge for learning objective AP Psych 3.8.A, and it typically appears in multiple-choice scenarios about reinforcement, punishment, shaping, or superstitious behavior. No released FRQ has used the term verbatim, but explaining why a behavior increases or decreases relies on it.