Because in a busy environment (where consistently more than one person uses the elevator) the scenario of making a wrong decision and having the wish to correct it occurs far less than the scenario where someone does not pay attention to which floors have been selected already and deselects your destination. At the worst case this means that you both miss your stop because you both did not notice.

Might also get confusing if the LED indicating the button's been pressed stops working

This comment right here is an example of thinking like a good designer. No amount of sleek surfaces and cool lighting can beat this.

Leave the button recessed after it's been selected, even if the LED fails (how often does this actually happen?) it's still a visual and tactile indicator.

To deselect the floor, simply press in again.

Those buttons are expensive and fail relatively quickly. It's a good idea, though.

Remove the buttons entirely and replace with a QRcode/NFC thing where each rider can vote/unvote where he personally wants to go. This can also work outside before the elevator arrives so a routing system can decide to bundle up a bunch of people going to the same floor in one express elevator. Haven't thought out how the ux would look to keep the wrong people out of that one elevator.

Many elevators in tall buildings have you select the floor when you arrive at the elevator bank, then it assigns you an elevator (usually denoted with letters A, B, C, D etc). When that elevator opens you get in (along with other people who were assigned that elevator), and it will stop at your floor (as well as other floors for other people).

Otis has a touch-screen system where you enter the exact destination: https://www.otis.com/documents/256045/11235683/22032_Compass...

> Remove the buttons entirely and replace with a QRcode/NFC thing where each rider can vote/unvote where he personally wants to go.

My local pizza place plays music based on customer voting through a smartphone app. It's not necessary to be there in order to vote - you just need the app.

This elevator design could be fun in similar ways.

Yeah, that's why I added NFC to at least approximate presence.

Now you made the buttons even more complicated, requiring some sort of magnet or motor in addition to a simple LED. And what do you do when that fails?

Also, malicious fighting over selecting and deselecting destinations

Yes, some elevator environments are busy. But many aren't.

There are two cases where deselecting a floor would complicate the logic:

1. When the currently targeted floor is deselected and the remaining selected floors are all in the other direction: Then the elevator would have to either reverse course without stopping — a situation which otherwise doesn’t occur and would be unexpected and possibly dangerous for the passengers — or stop on a non-selected floor before changing direction, which would be confusing as well.

2. The deselected floor was the only selected floor: The elevator would then have to choose a floor to stop on by itself — e.g. the next one it can safely stop on — which is also a situation that doesn’t otherwise occur. In addition, deselecting the only selected floor doesn’t seem to be a practical use case.

So instead of having to define, implement and test a behavior for those odd situations, it’s safer and less costly to just disallow deselection.

I didn't think elevators permitted scenario 1 to occur at all; I thought they refused to allow selecting floors not in the direction of travel.

(I don't usually board elevators traveling in the wrong direction, ofc., so, I'm not that sure.)

I haven't done it in a while but my recollection is that if you press a "wrong-direction" floor it will just go there after having completed all the previously-selected stops.

not just previously selected but it will wait until there are no stops in the current direction, then switch directions and go in the reverse order

Yeah I wasn't sure what will happen if more people add in stops in the "right" direction afterwards, I don't think I've ever been in that situation, but that makes sense.

The one in my building will allow you to select any floor at any time. it always goes to the last stop in the current direction before reversing as far as i have noticed

I've experienced both kinds of elevators. Some don't let you select a floor that's in the wrong direction, so you can notice you entered the wrong elevator and get back out.

Rather than testing these scenarios, couldn't one simply just(tm) not allow deselection in these scenarios?

Then you’d have to test that. And it would still be confusing to users that deselecting only sometimes works.

Right.

HN is not representative of the average person, or even a standard cross section of society. A elevator has to be legible to an 8 year old child, an 80 year old retiree, someone who is blind, a person who is deaf, etc.

When designing for such a broad audience, KISS (keep it simple, stupid)

I imagine that's by design. Otherwise you could unselect other people's choices.

Yes of course it’s by design. I just wonder why.

In Marc-Uwe Kling's "Qualityland", reversing elevators, turning around subway cars, and flicking traffic lights is a level-skill obtained by accumulating social credit points.

[1] https://www.amazon.com/Qualityland-Visit-Tomorrow-Marc-Uwe-K...

Not worth complicating the UX to address such a minor issue.

This is it exactly. It opens up the door to even more complexity in the design...

Now that you can unselect floors, if the elevator is on its way to the 5th floor and you unselect it, should it skip that floor mid-movement?

If there's only one floor selected, we'll probably want to disallow unselecting it while the elevator is moving, but what if you just hopped on and it hasn't moved yet?

This would probably make for an interesting interview question.

Minor to you... Introducing a great experience is the job of good UX. Not simply limiting options and saying 'done'. I am sure there are better options to handle this. Seems like no-one has put the effort into it (yet).

Unnecessarily stopping at a floor for a few seconds is minor to literally everyone riding in a public elevator.

But yeah, I'm sure that at all of the various elevator companies, over all of the years that elevators have had electronic controls, nobody has bothered to put any thought into this.

Limiting options is exactly the point. Elevators are supposed to be easy to use for the entire population, including the very young, the very old, those with disabilities, those not able to read or write the dominant language, etc.

In these cases, it is simply the best UX to keep everything really simple.

Because you could deselect other peoples choices.

This isn't an argument, as you can also select other people's non-choices.

There's some incentive not to do that, however, because in many cases it will inconvenience you just as much as everyone else. But if you could just deselect all the floors between the current one and your destination, there's a pretty strong incentive there.

Until someone punches you out, of course, because it'd be hard to hide and you're in a confined space with them...

Elevators sometimes have an anti-mischief feature where they will deselect every floor if all the floors are selected in a brief period of time. The cab will slow to a stop if no new buttons are pressed. It’s kind of eerie, actually.

Neat! How do you know this?

The elevators at my office were upgraded a few years ago and one of the elevator techs happened to mention it to me. I tried it out while alone, for obvious reasons.

Cool. I was hoping for something other than "I exhaustively test all new elevators".

That's a one way ratchet. Once selected, the fight is over.

If you can go back and forth, it would probably get violent.

That doesn't prevent people from getting to their destination.

It isn’t an argument. It’s a statement of fact.

How do I go about deselecting other people's choices, if that's my specific goal? I can get whatever I want in Jira, but nothing in elevators. It's fucked.

Maybe ask a woman?

Elevators in Japan often support this; usually either a double-tap or press-and-hold the button to deselect.

Some elevators are clever enough to detect kids messing with them. If you select enough floors, they'll just deselect everything soon, including your errant selection.

Admittedly, that's not very helpful unless you somehow knew that the elevator you were in had been configured in such a way.

> But: The one big question I have with elevator UX is this: why isn’t it possible to deselect a choice? So pressed 10th floor but wanted 11th. There is no way to press button 10 and then button 11 to correct that mistake.

In many elevators, one can double-press a button to deselect it.

Now I have a lot of testing in front of me.

The elevators in my building do support this. People get confused all the time by accidentally deselecting the floor because they didn't notice it was already lit up. Also, the "G" light is broken in one of the elevators, which causes even more confusion (until you realise that it's not broken on the second, lower set of buttons for people in wheelchairs).

I suspect you are thinking like a lawful-good individual engineer. You are solving a niggle, without considering the human and engineering compromises you would discover if you worked in the industry.

You are perhaps trying to optimise for a one-person elevator trip, rather than thinking of what is the optimum for a repeated game with many concurrent trip players that includes both cooperator players and defector players. An elevator is a common good to its users.

If people could cancel a destination, then there is less incentive for people to have to prethink their destination before getting on the elevator. Leading to more likely to waste concurrent elevator users’ time in the long run?

If you could cancel a destination, defector players could cancel your destination to speed up their trip (with resulting policing and status meta-games etcetera).

Elevators mostly have the lowest-common-denominator for a UI. Where is the incentive for elevator purchasers (building procurement or facilities) to demand an improved UI? Would a manufacturer get any profit by providing an improved UI? Would such a UI be accessible to the blind? Discoverable? Usable? Cleanable? Predictable (e.g. elevator arriving indicators on destination floors)? Safety? Complexity?

There are a huge number of factors to building anything complicated.

Also see https://danluu.com/sounds-easy/ and https://fs.blog/chestertons-fence/ and all of the elevator wiki starting here https://elevation.fandom.com/wiki/Fire_service_mode_(EFS)

Disclaimer: I’m not an elevator engineer. I feel your pain: I want a government department of niggles which catalogues minor complaints and gets them fixed. Although I admit I am pessimistic enough to think it would only end up increasing the total number of niggles due to second-order effects.

Every single elevator in Korea allows you to deselect a floor by simply pushing the button again.

You'd be surprised how often it comes in handy and have never had an issue with anyone deselecting someone else's floor.

It seems like every lift I've been in in China ( been here for 8 years) has this functionality where if you press the same button in rapid succession about 5 to 15 times, it will depress.

In the Philippines (tested in Manila) high rises this seemed to be a common feature: Double clicking a selected floor would deselect.

If I were to guess, people enter the elevator and subconsciously just press which floor they want to go to. If you allow deselecting, someone will inadvertently deselect where they want to go to if that button is already selected.

I agree. Should be a "hold the button for 5 seconds to deselect"

In smaller installations (e.g. private homes) this is the functionality provided by some lifts: push once to select, double push to de-select a floor.

In larger/public settings, offering this would be counterproductive, for the reasons listed by sibling comments.

Some elevators have this! The one I encountered was, press the button until it starts flashing, release and press again to deselect the floor.

I have been to a few elevators in India where you can deselect a choice like you described. However they are not rare.

Every elevator in Korea works this way. Pressing once selects, pressing again deselects.

Perhaps you could answer the two questions here, preferably relating to a named elevator model: https://news.ycombinator.com/item?id=32005810

And maybe answer my question too: how do blind people know if they are selecting or deselecting?

Watching foreign button-mashers must be amusing!