Gmail's Email filter checkbox or radio?

Question

I was just trying to filter the emails I was getting from the particular site and the time when I clicked on filter messages like these and then to Create a filter to this search, it opened some options which confused me being simple .

Now every option has checkbox which means a user can select multiple options.

My concern is with last two options gmail is providing

So what is this?

• Is it something google did intentionally?
• Is there anything hidden about these checkboxes?
• Although I can't select never when always is ticked but to check never, I have to uncheck always first and then choose. So why not a different div with radio buttons in these two?

Answer 1

It's very likely, there is a reason behind such solution.

Let's say we develop that block and replace the checkboxes with a group of radio buttons:

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When one of them picked:

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There is no workable way to disable a radio button, cause we we might want allow Google to determine letters' importance automatically, that should not be affected by our filter.

Thus a new option should be introduced for that:

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It looks confusing without a title, let's add it:

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Hmm... Perhaps, we should go back to a couple of checkboxes:

^{download bmml source}

Answer 2

As designers we are not typical users. Normal people don't analyse checkboxes like you just did so they probably won't be confused by the illogical aspect of it.

The use case of this page is likely that the user selects one or two options and moves on, they don't go clicking back and forth. Showing a list of checkboxes is the cleanest and simplest way to display and in general the principle applies. With a complex combination of different elements, although semantically correct, it would be harder to find the right options. I reckon they tested it and this was easiest for users.

Most people understand the difference between checkboxes and radio buttons when they use it but won't be able to give you a good answer if you ask them to explain the difference (without looking at examples).

Answer 3

Google has implemented the simplest thing (from the user's point of view) that meets the needs of the situation, namely:

• provide all of the options needed to enable the user to achieve their objective
• make it clear what each option does
• prevent users from choosing a combination of options that cannot work together

Yes, it would be possible to do this differently (as shown by other answers here), but all (?) of the other ways I can think of are more complex for the user than what Google has implemented.

In a real-life situation, a user is very unlikely to choose one of these mutually-exclusive options and then try to choose the other as well. In nearly all cases, they will just choose the one they need and not pay attention to the other one. Google prevents them from selecting both, just in case. So, very few (if any) people will have the minor inconvenience of having to first uncheck one before being able to check the other.