Ninety-five times out of a hundred, the choice is mechanical: affect is the verb, effect is the noun. Here is the rule, the memory trick that makes it permanent, and the two rare exceptions worth knowing.
THE SHORT ANSWER
Affect is almost always a verb meaning to influence: ‘The weather affected our plans.’ Effect is almost always a noun meaning the result: ‘The weather had an effect on our plans.’ Remember RAVEN — Remember, Affect = Verb, Effect = Noun.
Few pairs of English words generate more hesitation than affect and effect. They sound nearly identical in speech, they live in the same kinds of sentences, and both concern cause and consequence. The good news: the distinction is one of the most reliable in English usage. Learn the core rule and you will be right in the overwhelming majority of sentences you ever write.
The core rule: verb versus noun
Affect is a verb. It names the action of influencing something. Effect is a noun. It names the result that an action produces. If you can replace the word with ‘influence’, choose affect. If you can put ‘the’ or ‘an’ in front of it, choose effect.
The new law will affect small businesses. (influence)
The new law will have a lasting effect on small businesses. (a result)
| affect | effect | |
|---|---|---|
| Part of speech | Verb (rarely a noun in psychology) | Noun (rarely a verb in formal prose) |
| Core meaning | To influence; to act upon | A result; a consequence |
| Test | Can you say ‘influence’ instead? | Can you say ‘the result’ instead? |
| Example | Heat affects metal. | Heat has an effect on metal. |
The RAVEN mnemonic
If you learn one trick from this guide, make it this one. RAVEN stands for: Remember, Affect = Verb, Effect = Noun. Both words keep their initials honest — A for the Action word, E for the End result. Writers who internalise RAVEN stop pausing over this pair entirely, usually within a week.
Exception 1: ‘effect’ as a verb
In formal writing, effect can be a verb meaning to bring about or to cause to happen — not to influence something, but to make something exist. It is common in bureaucratic and legal prose and almost nowhere else.
The committee hopes to effect real change. (= bring about change, not merely influence it)
Notice the difference in feel. To affect change would mean to influence change that is already under way. To effect change is to cause the change itself. Because readers so often assume ‘effect change’ is an error, many editors avoid the construction altogether — but it is correct, and you will meet it in serious prose.
Exception 2: ‘affect’ as a noun
In psychology and psychiatry, affect (pronounced AFF-ekt, with the stress on the first syllable) is a noun meaning a person’s observable emotional state or expression. Clinicians write about ‘flat affect’ and ‘inappropriate affect’. Outside clinical writing, you are unlikely to need it — but if a sentence about a patient’s demeanour uses affect as a noun, it is deliberate.
A thirty-second decision procedure
- Ask: is this word doing the action, or naming the result? Action → affect. Result → effect.
- Try the article test: if ‘the ___’ or ‘an ___’ sounds natural in front of it, it is a noun → effect.
- If a form of ‘have’ or ‘take’ precedes it (‘had an effect’, ‘take effect’), it is effect.
- When genuinely stuck in formal writing, reword: ‘influence’ and ‘result’ never confuse anyone.
Editor’s note — The pair appears in our Word Check tool at the top of this site. Type ‘affect vs effect’ there for the verdict card version of this guide.
Frequently asked questions
Is ‘affect’ always a verb and ‘effect’ always a noun?
Not always, but close. Affect is a verb in the vast majority of uses; its noun use is confined to psychology. Effect is a noun in most uses; its verb use (‘to effect change’) appears in formal writing. For everyday writing, treat the rule as absolute and you will be right nearly every time.
What is the difference between ‘affect change’ and ‘effect change’?
‘Effect change’ means to bring change about — the change would not happen without you. ‘Affect change’ means to influence change that is already happening. Most style guides accept ‘effect change’; it is the more common phrase in formal writing.
How do you pronounce the noun ‘affect’?
The verb affect is pronounced uh-FEKT. The psychological noun is pronounced AFF-ekt, stressed on the first syllable — one way professionals signal which word they mean.
