You can affect an effect
(but you shouldn't effect an affect — that's acting)
     The words “affect” and “effect” are frequently misused and confused, one being used incorrectly in place of the other. But they have no senses in common.  Both words can be used as either nouns or verbs, so that's not a foolproof distinction.  But “affect” is almost always a verb, whereas “effect” is more commonly used as a noun than it is as a verb. “Affect” as a noun is almost entirely reserved for psychological jargon. Its use as a noun by a journalist is an affectation. 

     “Affect” as a verb.  (The norm) To have an influence on; to impress or to move; to produce a change in something or someone. Example: 

    His study was intended to show how alcohol affects reaction time. 

    “Effect” as a noun.  (Common usage) Something brought about; a result. Example: 

     They discussed the effect of the law on children. 

    “Effect” as a noun (Common usage) The way one thing acts upon another. Example: 

     The effect of the law has been to increase the use of alcohol. 

    “Effect” as a verb.  (Not common, but acceptable in rare cases.) To produce a result; to cause something to occur; to bring about an outcome. Example: 

     Smith said the cutbacks were designed to effect basic economies for the company. 

     While correct in this case, is it really clear to all readers? A better alternative: 

     Smith said the cutbacks were designed to implement (make happen) basic economies for the company. 
     Smith said the cutbacks were designed to bring about (produce a result) basic economies for the company. 

    “Affect” as a noun.  Forget it; you're in journalism, not psychiatry (though you might wind up in therapy). “Affect” as a noun means an emotional state as contrasted to a cognition. “Affect” is a dimension of behavior rather than a separate segment of it.  “Affect” is thus experienced at the same time that perception, performance and thought are going on. (See, I told you to forget it!)  As for the second line of the headline at the top of this missive, “effect an affect” would mean to cause a certain affectation or trait to occur. In other words, acting, something Robert DeNiro does and Ben Affleck tries to do, but not as well.

A quick & easy guide
to “affect” and “effect”

    It's easy to get caught up in a debate about the subtle shades of meaning for the words “affect” and “effect.”  Such debates waste time and energy.  So it is useful to sharpen your understanding so that with a minimum of thought you can make a good editing decision when you encounter one of these words.  The following thoughts are intended to help equip you for such. 

     1. Determine if the usage calls for a verb or a noun. 

     2. If a verb is needed, 95 percent of the time or more the word you want is “affect.”  It means to change or to alter.  “The weather affects our moods.”  “Nutrition affects health.” “The seasons affect trees and flowers.” “The quality of your work affects your grade.” 

     3. The occasional need for “effect” as a verb arises when the narrow meaning “to cause or to bring about” is appropriate.  These rare occasions often occur in some form of the expression “to effect a change” or, in police jargon, “to effect an arrest” (to cause or make an arrest happen). Nevertheless, it’s still best to avoid, particularly in the last example because it’s simply police jargon, and it's good to avoid jargon. 

     4. When a noun is required, the word is almost always “effect.” This means “a result.”“The effect of diligent study habits is better learning.” “The effect of making the correct choice is a better grade.” (Do you sense a theme here?) 

     5. “Affect” can be a noun, but its use is almost entirely reserved for psychological jargon.  You could have a long career as a writer and editor and never encounter the need for the noun “affect.” 

     6. So be ready to make almost all verbs “affect.” 

     7. And be ready to make virtually all nouns “effect.” 

Updated July 27, 2012