I was discussing with a workmate whether user interfaces should be phrased in a positive or a negative manner. I've observed positive sentences are clearer than negative ones to the average user.

I've heard some discussions on this matter and most people seem to agree that phrasing positively yields better results in user experience than negative ones. But is there a UX recommendation on this?


to be clearer: should I notify my user that his/her input data is invalid by saying "input is invalid" or "input is not valid"? Or does it not affect UX at all?

Is it better to negate a positive verb or use a verb that has a negative meaning in itself?

  • Do you have some examples? This is difficult to answer generally... Commented Apr 24, 2014 at 17:39
  • @DanielNewman things such as "input is invalid" or "input is not valid".
    – Mauren
    Commented Apr 24, 2014 at 17:39
  • 1
    also... ux.stackexchange.com/questions/48256/… Commented Apr 24, 2014 at 17:46
  • 3
    Context is important. If the form is for grandma to sign up for pinterest, a friendly 'voice' with positive wording would make the most sense. If we're talking about entering nuclear weapons launch codes, I think we can forgo the formalities and get rather demanding with our error messaging.
    – DA01
    Commented Apr 24, 2014 at 18:38

2 Answers 2


UI error messages should be direct, objective statements which the user only has to read once to understand.

I personally perceive zero differences between input is invalid and input is not valid

^ However if I came across either of those messages then I would immediately assume the programmer was too lazy to tell me what was invalid and now I have to go on a wild goose chase.

What I perceive as good messages:

  • Digits only please
  • Email is not valid
    • Go one step further and say something like only one @ symbol allowed
    • Or list out valid email chars
  • 6 character minimum
  • 3 characters to go
  • Please use m/d/yyyy format here
  • Max Qty.: 3 - If you need more then give us a call right now (555-555-5555)
  • I totally agree on the "detail" thing. However our arguing was more related on whether or not to put "not" in a sentence when there is a verb meaning exactly what a "not verb" would mean. See my edit.
    – Mauren
    Commented Apr 24, 2014 at 18:45
  • 2
    @Mauren I personally think that if you're worried about having anything negative in your errors to avoid using "not", "no" and work with words that mask the "negativity" as it were. Go with "Input is invalid" and perhaps take the advice above and get more descriptive with the error.
    – Nick_M
    Commented Apr 24, 2014 at 18:49
  • 1
    I see, in my humble opinion: invalid would be preferred if it was the first word such as Invalid username, try again but if it's buried in the statement somewhere then go for not valid like this: Error: username is not valid
    – MonkeyZeus
    Commented Apr 24, 2014 at 18:50
  • 1
    If you perceive not as a negative word then try phrases like Fix the username. It's all about context ;-)
    – MonkeyZeus
    Commented Apr 24, 2014 at 18:53
  • I'm not sure how much it matters, but note that the word 'invalid' has two entirely different meanings depending on how you pronounce it. in-VAL-id vs. IN-vuh-lid
    – DA01
    Commented Apr 24, 2014 at 20:14

Realistically, "input is invalid" and "input is not valid" are the same. Neither is a negative frame of the other.

Typically, negative frames are not recommended, because the mind typically has to flip itself to understand the instruction. For example, "Don't think of an elephant" is an impossible instruction to follow.

In other words, you may accidentally elicit the opposite action from your user if you frame it negatively. Best to frame things positively, and with imperatives (i.e., "Do this") wherever possible.

Other examples:

"Don't click submit until you have filled out every field in the form" would be a silly thing to write at the top of your form. You'd probably get more people clicking submit before the form was fully filled out.

"Entry is invalid" does not tell me what I should do - it only tells me that what I did was wrong. How about: "You must enter a valid email address"

"Your password must not include the following characters: !^@$%))($" <--This may be necessary to state, but is really awful UX. It is easy to miss the "not" in that sentence. Best to let them use one and then with a validation/warning say "Your password may not include any of the following characters: !^@$%))($"

That being said, negative frames do have a place - and it usually involves inhibiting an expected action:

"Don't use the back button!" "Do not refresh the page!"

But these MUST come with an imperative, positive statement of what to do instead. It is also good to include a reasoning behind the warning.

Not the answer you're looking for? Browse other questions tagged or ask your own question.