Two of the most commonly confused words in English are "affect" and "effect." Obviously, these words are confusing because they look alike and share the same root ("fect," from the Latin facere, meaning "to make or do"). In addition, both words have both noun and verb forms, which makes them harder to distinguish. In this post, I clarify the various meanings of both "affect" and "effect" so that you can better understand when each word is appropriate.
Verb: "To Influence" (Also "To Feign" & "To Cultivate")
"Affect" is primarily used as a verb, and the meaning that you are likely most familiar with is "to influence." Indeed, "affect" is a very common verb for expressing cause-and-effect relationships. These sentences contain correct uses of "affect" as a verb:
Changes in weather have been shown to strongly affect most people's moods. Even a small change in salary can dramatically affect a worker's happiness.
Note that "affect" in this usage is neutral in tone; it does not necessarily indicate a positive or negative influence—just some kind of influence.
"Affect" also has a couple less common meanings. If you are a beginning English speaker, you do not need to worry about these (so you can feel free to skip to the next section), but if you are reading or writing college-level texts, then knowing these other meanings will be helpful. The first of these other meanings is "to feign," as in this example:
Though Matt is from rural Kansas, he affects an Eastern accent to seem more sophisticated.
As you can see, "affect" in this sense is meant to indicate that the action is inauthentic; it thus has a slightly negative connotation.
Finally, there is the sense of "affect" that means "to cultivate," as in this example:
Matt also affects an advanced understanding of art theory through numerous gallery visits.
In this sense, "affect" indicates an ongoing effort to acquire skills or knowledge that one did not previously have. Unlike in the previous sense, there is no air of inauthenticity to this usage; it is mostly a neutral expression of a person's development.
Noun: "Demeanor"; "Mindset"
As a noun, "affect" refers to a person's emotional state—in particular, to the ways in which that emotional state expresses itself in that person's facial and bodily expressions. This is a somewhat rare usage in everyday speech, but it is commonly used in certain fields, including psychology and sociology (e.g., to comment on how study participants seem to react to a stimulus).
Here are a couple examples; notice how the noun form of "affect" is always used with emotion words (underlined):
At the conclusion of the test, most of the students showed a relieved affect. The affect of the subject varied wildly, from excited to downbeat, within a 5-minute span.
When using "affect" as a noun, ask yourself if you are referring to emotions (or emotional expressions). If so, "affect" is likely correct, but if not, you likely need to use "effect" instead.
This noun usage of "affect" is also the root of the adjective "affective"—meaning "emotional" or "related to emotions." This is not to be confused with the much more common term "effective" (see below).
Noun: "Result" (Also "Distinctive Impression," "Operation," and "Goods")
The noun form of "effect" is the most common usage, and the dominant meaning is "result" or "influence." In this sense, "effect" is used to refer to a result of an action or a more general influence, as shown in these examples:
The side effects of many cancer treatments include hair loss. Despite the manufacturer's numerous claims, the supplement had no noticeable effect.
There are several other meanings of "effect" as a noun, however, and most of these are in common usage. The first is "distinctive impression." In these uses, "effect" relates to the impression that an action or product creates in people, as in these examples:
Many children use tantrums to good effect, as a way of getting what they want from adults. The film's subpar special effects left many to wonder why they were watching cats sing.
The next meaning is "operation"; in this sense, "effect" is usually used after a preposition such as "in" or "into," and it conveys that something (a law, a policy, a rule, etc.) is operative. Here is an example:
The ban on plastic grocery bags has been in effect since last June.
Another meaning refers to "goods" (as in physical products). In this sense, the term is usually plural ("effects") and often refers to a person's belongings. Here is an example:
The guard gave Rita only 5 minutes to gather her effects before he led her off the premises.
Finally, I should mention the common phrase "in effect," which means "in substance" and is typically used as a contrast between what something is supposed to do and what it actually does. Here is an example of "in effect":
The new bill does lower taxes but, in effect, it ensures that the city will go bankrupt.
The noun form of "effect" is also the source of the adjective "effective" (not to be confused with the less-common term "affective," described above). Though most uses of "effect" are neutral, "effective" is always a positive term, as it implies that something has the intended effect.
Now, let's talk about the less-common verb usage of "effect."
Verb: "Create"; "Accomplish"; "Put Into Action"
The verb usage of "effect" is mostly confined to formal writing, so if you are writing informally, you should probably use another word. However, if you are writing a formal paper or business proposal, "effect" can be appropriate. It is usually used to describe how a goal is going to be accomplished or how an intended change is going to be created. Here are a couple examples, with the goal or change underlined:
The regulatory bureau was created to effect a safer environment for construction workers. The lawyers met for over 8 hours to effect a mutually beneficial settlement.
When determining whether to use "effect" as a verb, consider whether you are referring to the implementation of a goal or result. If so, "effect" is probably fine, but if not, you likely mean to use the more common verb form of "affect."
I hope this post has been helpful. As always, if you have any questions, please do not hesitate to ask me, either in the comments or via email (email@example.com). Thank you for reading, and please visit ElevationEditing.com if you need any editing!