Affect v. Effect
Affect and effect are notoriously tricky. It doesn’t help that each can be both a noun and a verb, so you’re actually dealing with four words rather than two. To keep all these straight, know how the words get used most often and how the meaning changes for the less common usages.
Common Usage
Affect – a verb
Definition: To have an impact/effect on something; to make a difference
Examples:
- Traveling to another country will affect how you perceive your own.
- Sleeping more will affect your health in a positive way.
Hint: To test your word choice, look at whether the sentence makes sense with another action word like alter, modify, transform, etc.
Effect – a noun
Definition: The outcome, result, or aftermath of something
Examples:
- What effect will this have on our learning?
- The medical side effects of this drug are very well understood.
Hint: Test whether the sentence works with another noun (e.g., What impact will this have on our learning?); also look for articles – they'll not always be used, but they can be a sign that you need a noun and not a verb.
Less Common Usage
Affect – a noun
Definition: One's demeanor or emotional state. Also, an observed response.
Examples:
- The patient had a very positive affect.
- Psychiatrists often consider a person's affect.
Hint: When used, it's often used within psychology or psychiatry (but, of course, not always). Affect (the noun) is something that a person has or that one observes in a person.
Effect – a verb
Definition: To cause something to happen; to produce a result; to start to apply
Examples:
- They were happy to know that his release had been effected.
- It will take at least a decade to effect changes that benefit all students.
Hint: This verb means to cause something, to make something change, or to implement something, so consider whether it’s possible to use implement, produce, engineer, or similar verbs in the sentence.