Affect and Effect - how to choose the correct word

Every writer knows, you have to get the details right.  Using the correct word in the correct place is not a matter of style or presentation, or one of pedantry - but one of grammatical accuracy.  Getting it right is the difference between expressing oneself clearly or not, so it’s worth reviewing the differences.

Affect

Let’s look at affect first.  Affect is generally used as a verb, in which case its meaning is to influence – it does not mean to cause.  For example, ‘that goal could affect the outcome of the whole tournament’ – indeed, affect is often used in the conditional tense, because it’s tentative.  It refers to contribution, not causality – ‘that superb presentation might well affect his chances of promotion’.

Affect can also mean to dissemble, or act in a way that isn’t authentic -  as in, "She affected an air of indifference, despite her severely hurt feelings”

Can you use affect as a noun?  Yes, but it’s meaning is very specific, and according to the AP stylebook, rarely useful in everyday writing, unless you’re writing a social psychology textbook.  Unless you are describing a particular emotion or mental state – ‘she had a pale, inattentive affect’ -  using affect as a noun is incorrect.  ‘Affectation’ is a noun of course. 

Effect

Effect is commonly (and correctly) used as a noun, and it means the specific result.  For example, ‘changing to the other brand of fuel had no noticeable effect on performance speed’, or ‘I don’t like the effect of that blue background, it makes the whole thing look washed-out’.  It can refer to a fact or an opinion, but it is about the result.

As a verb, effect means TO CAUSE or to bring about – it’s a transitive verb, and often misused or confused, particularly in business communications.  Notice the difference:

“The corporate takeover was effected swiftly” (caused/brought about)

“The senior management team was severely affected by the corporate takeover” (influenced)

So, why the confusion between the two?

Well, the two words do sound similar, they’re hominyms.  Even if the speaker is using them correctly in the first place, which clearly can’t be guaranteed, it’s difficult to hear the difference.  The first syllables of both can merge into a generic ‘uh-fect’, that really could be either…  They are similarly derived, and also have similar and potentially overlapping meanings – so the context is very important, in deciding which one could be being used – or should be being used. 

Once you add the fact that they can both be used as either nouns or verbs, it’s easy to see why the confusion happens!  You can adopt a rough rule of thumb that affect should be used as a verb and effect as a noun, and indeed this is often stated in beginner and intermediate studies of English as a foreign language.  You won’t go wrong too often using this rule, but the examples above indicate it isn’t universally applicable.