Affect and effect are so often confused, they are practically the original common grammar mistake. They are misconstrued nearly every which way, everywhere, on a nearly daily basis. Of course, all these errors are easily avoidable, and here’s how.
First, you have understand the intrinsic differences between these two words. For the most part, this difference is actually pretty straightforward: one is commonly used as a verb (affect) and one is commonly used as a noun (effect). Easy, right? These two can actually be switched but let’s start with the basics first.
Affect, as a verb, means to influence, as in “My recent lottery win has affected my spending habits greatly” or “His recent knee surgery affected his gait.”
Effect, as a noun, means a result, as in “My recent lottery win had a clear effect on my spending habits” or “His recent knee surgery had an obvious effect on his gait.”
Here’s an easy way to tell them apart:
An Affect is an Action, but an Effect is an End result.
Awesome, right? Now, let’s move on.
Rare uses of Affect and Effect
So, I hinted above that these two can be used differently than how I had previously explained. In rare instances, they can, in particular circumstances.
In psychology, affect can be used as a noun– as in, “She displayed a happy affect.” This definition is used in psychology to signify the difference between knowing a person’s mood really is and knowing what their mood appears to be. Meaning, it’s hard to discern whether the person (or, really, patient) is actually happy or just appearing to be happy. In psychology, this difference is important.
Effect, in turn, can be used as a verb, meaning to bring about, cause, or accomplish. For example: “The President hoped this new program would effect change.” Here, effect is used as a noun. Here is another example: “Andy effected his escape from prison with a rock hammer and a carefully placed poster.” Of course, this usage is less common; it is used predominantly in political writing and journalism.
Like most common grammar mistakes, these two words seem confusing but, with a little thought and maybe a memory trick or two, they’re actually very easy to tell apart.