Validation message when only one thing can go wrong

Question

We have a very simple form overlay for adding items (let's say cars) to a list. There can only be one error, which is to enter a duplicate car name.

We've had a rather split opinion on the team as to displaying a validation message immediately or not, so in one case we simply display a (!) icon next to the field, and in the other we specify that the name is a duplicate, as soon as a duplicate is detected.

In the case that we don't display a message, a message is displayed if the user tries to submit, so they will learn what the (!) means.

So to be clear, there is only one thing that can go wrong on the form. Should we say what has gone wrong every time, or should we trust that the users will learn?

Answer 1

I agree with colmcq except I would write it like this:

As a frequent user of websites and forms (job-seeker since Decemnber 2013 - registered on Monster, CV Libraray, JobServe, JobSite etc) I would say MY preferences are:-

1. When I fill in a form I want to know straight away that an input has been filled in incorrectly NOT after submitting the form [depending on implementation that can be as you are typing, constantly checking as angularjs does or upon completion of the input box and moving to the next one, perhaps by making an ajax call onBlur() or similar (assuming it's not the only/last one)]

2. I want to know exactly what the error is (if possible) and not have to guess

Error messages should be written in a language the user can understand and should provide instructions that help them recover from the condition that created the error in the first place

I couldn't agree more.

Answer 2

Displaying the error as soon as it is detected is good and inline validation is better than on submit validation.

There is nothing wrong with telling the user exactly what the error is as opposed to a (!); as I would say:

Error messages should be written in a language the user can understand and should provide instructions that help them recover from the condition that created the error in the first place