I just started working with a new client for whom I am copyediting several hours a day, and every time I run into affect or effect, I stop and ask, Is it used correctly? Is it a verb or a noun? Should it be affect with an a or effect with an e? Every time. Fortunately, the client appears to understand this rule. Yet still I pause and consider. I bet I’m not the only one.
Affect Is a Verb; Effect Is a Noun
Affect is usually used as a verb that means “to produce an effect upon”—there it is again!—or “to influence”:
Yesterday’s unusual weather affected Jim and Derrick’s plans to go to the beach.
Effect is usually used as a noun that has a lot of different meanings, but it gets confused with affect when it’s used to mean “a result”:
The effect of the thunder and rain was that they went to a museum instead.
Grammar Girl offers this “quick and dirty tip” for remembering the difference between affect and effect: “Because effect is usually a noun, that means you can usually put an article in front of it and the sentence will still make sense”:
At the Getty, Jim admired the effects of brushstroke, color, and composition in van Gogh’s Irises.
However, you can’t insert a, an, or the before affect because it wouldn’t make sense to use an article with a verb:
The artwork, however, did not [the] affect Derrick.
Grammar Girl’s trick, then, is to try putting the before affect and effect when you run into either of them in a sentence. If the sentence still makes sense, effect is a noun and should start with an e. If it doesn’t, affect is a verb and should start with an a. You can remember which is which “by remembering that the ends with e and effect starts with e, so the two e’s butt up against each other.
Except When Affect Is a Noun and Effect Is a Verb
This trick will work most of the time but not always, because sometimes effect is a verb. In these cases, it means “to cause to come into being” or “to accomplish”:
Jim hoped to effect a change in Derrick’s attitude by showing him the museum’s photography collection.
Meanwhile, very rarely, affect is used as a noun in psychology to describe an emotion:
Derrick exhibited a positive affect in the photo gallery.
AP advises that this use of affect “is best avoided. … there is no need for it in everyday language.”
Usually, though, affect and effect will refer to the verb and noun forms of basically the same causal concept—“to influence” versus “an influence”—and the rules and tips discussed in the first part of this post will apply.
“affect.” Merriam-Webster Online Dictionary. 2009. Merriam-Webster Online. 4 June 2009 http://www.merriam-webster.com/dictionary/affect
“effect.” Merriam-Webster Online Dictionary. 2009. Merriam-Webster Online. 4 June 2009 http://www.merriam-webster.com/dictionary/effect
Chicago Manual of Style, The. 15th ed. Chicago: The University of Chicago Press, 2003.
Fogarty, Mignon, Grammar Girl’s Quick and Dirty Tips for Better Writing. New York: Holt Paperbacks, 2008.
Goldstein, Norm, ed. The Associated Press Stylebook. 42nd ed. New York: Basic Books, a Member of the Perseus Books Group, 2007.