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(Older) pocket calculators sometimes have several “cancel” buttons (C, CE, etc.) Typically, the CE button would only clear the last entry but not interrupt the current computation. For example, if you press 10 + 1 CE, you would see a 0, but the calculator still expects a second operand for the addition (i.e. it still has "10 +" in memory). Often, there would ...
391
Other answerers have provided great logical reasons for how these habits could come about, but I think it is simpler than that (plus, how often are any of us logical?).
Calculators obviously have a state, since they do multi-step operations, but they don't clearly show their state. In many calculators, if you see a zero on the screen, you have no idea if ...
360
You need the bean container or filling mechanism to communicate in its physical presence alone, that it will not hold water. Additionally, emphazising what is expected, coffee beans, in form of an icon might help.
This is just a crude sketch to visually show what I mean by "physically" communicating that the water does not go in here. Devise the coffee bean ...
305
In my experience a USB plug needs a bit of pressure to go in the port. It’s enough pressure to make me wary that I might break it if I’m putting it in the wrong way.
After reversing the plug, it becomes obvious that it does not fit at all. This observation allows me to flip it again and now apply more pressure with confidence.
184
In a washing machine the objects that are being washed move around. It's a dynamic process, that is unpredictable and always unique. Watching the movement is fun, it indeed gives a sense of control to the user, even if it is not actually required. Quite a few people even find it relaxing to watch the washing machine.
The window also prevents users from ...
182
Besides the arguments others have listed (Aircraft requirements, power saving) we should not forget about security.
Before the tablet and smartphone era you had a great control over your computer in an emergency: if you pulled the UTP cable, you could guarantee that the computer is isolated from the network. If you pulled the power cord, you could guarantee ...
172
I believe the answer is actually because of building codes. If a room has only one entrance, it MUST open inwards. This is because if anything on the outside is blocking the door, it can still be opened, and then the person can clear the obstruction manually
Trying to push the door forward might not be enough to clear the obstruction depending on a number ...
170
Here in Finland the main reason is this:
Image source
Road markings are used to denote speed limits but never as a primary mean. And as Jung Lee points out, re-applying road paint is labor intensive, especially here, as studded tyres usually erode most of the paint in one or two winters.
Edit: The Finnish law actually states that road markings, such as ...
169
Security
A hardware radio switch has security benefits to it in that when it is off, you know for a fact that nothing is connected to your laptop wirelessly. The radio switch usually turns off all wireless communication, including Bluetooth and 3G.
I have heard that this is a requirement in certain military environments, but I have not seen any evidence ...
165
A Google search doesn't really provide me any answers but I do have some ideas on why the doors would close:
1: Time Efficiency (As stated by Andrew, Ruudt, and Angelo)
Closing the door reduces the time the elevator needs, to move to a different floor when someone presses the button.
2: Safety (1)
When a door stays open and a user approaches the elevator, ...
161
Short answer: Design commonly causes misalignment
Most plugs or ports have a flared edge, beveled plug or some other design that allows for the orientation of the plug to be slightly off and still match. USB doesn't.
Oftentimes, the first attempt will cause your plug to be aligned too high, slightly twisted, or some other orientation that doesn't allow it ...
148
Physical symmetry without symmetry of use
I'm surprised that so many of these answers are addressing the consequences of poor design without discussing what made it a poor design in the first place. The issue at hand here is that the USB devices have a correct orientation and that correct orientation is indistinguishable from the incorrect orientation.
In ...
146
It is a combination of manufacturing and usability... but mostly manufacturing.
Doing a quick web search for "why are soda cans round" (Google does a decent job) yields multiple insights in the issue. But the only result you need to visit is engineerguy's YouTube video (you should also be Subscribed to engineerguy, because he is awesome).
The Ingenious ...
136
This wikipedia page sums it up quite nicely
https://en.wikipedia.org/wiki/Intentionally_blank_page
Such pages may serve purposes ranging from place-holding to space-filling and content separation.
And the reason I see it most often
Intentionally blank pages are usually the result of printing conventions and techniques.... Book pages are often printed ...
134
Because, at the table, a shaker is entirely the wrong dispenser for sugar.
Shakers are used to sprinkle small amounts of a substance over an area, which is exactly what you want for salt and pepper. Sugar is used to sweeten drinks by adding a relatively large amount, which is just dumped in the drink and not spread over an area. If you tried to do that with ...
131
Closing the door for the floor the elevator is on reduces the time, the elevator can serve another floor upon request. The time is saved due to omitting the door closing step.
Considering that elevators usually serve more than two floors this speeds up the more frequent use case.
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I am in the fast food business having owned five units for over 30 years but don't have a unit with two lanes.
The reason for two lanes is a matter of timing from McDonald's research into this that I read years ago. (I am not with McDonalds.) It all comes down to timing and shaving 10 or 20 seconds off the time you wait in line is worth having. The slowest ...
122
Unfortunately such cable is not compliant with USB specification, as even in usb power delivery the data lines are used to negotiate power.
You should not mark it with USB (or even USB-like) logo at all. Plug's distinctive shape is informative enough to be easily recognizable as in "where does this plug go". I concur with other answers suggesting lightning-...
121
As you observe, connecting the machine to a water pipe removes the need to add water, but the need to add coffee leaves the user with one place to put water. So what we're looking for is a way to remove the need to add coffee; the user will then have nowhere to put the water.
The solution: Mains piped coffee beans.
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I'm guessing they viewed the button on the right hand side as the primary action button as it's closer to the users thumb, with the button on the left for secondary/less-used action, as it's slightly further away from the thumb (more of a physical exertion on the user).
They then may have wanted to label them accordingly - so A for primary button, B for ...
109
You are totally right
As with many other devices (eg the QWERTY keyboard) the hot/cold tap persists not because it's the most usable design, but because of:
Cost since proper temperature control requires an electromechanical feedback loop design, or calibrated thermostatic valves which needs to be periodically adjusted or replaced. This drives up the cost ...
106
In the event of a stopped dishwasher (due to electrical fault or buggy software or something) the water in the device streams out of ordinary drains inside, and the water sprayers stop adding more water. If you were to open it after it had shorted out, you aren't going to get soaked.
That's not true of a front-load washing machine. If one of these is ...
102
I think icons are the best possible way to convey the information about different flushing amounts. I see too much uncertainty by relying only on button relative sizes and ease of use.
It can be a simple pictogram showing the tank in the relative size of water what will be flushed upon pressing that button.
(source: sswm.info)
Or any other icons that ...
94
Historically
It is a simple fact that traffic signals were introduced in 1868. From The Origin of the Green, Yellow and Red Color Scheme for Traffic Lights:
In London, England in 1865 there was a growing concern over the amount of horse-drawn traffic causing danger to pedestrians trying to cross the roads. A railway manager and engineer named John Peake ...
93
On some old calculators, the clear button had double duty:
push once for clear-entry
push twice for clear-all
I think this meant that people tended to press clear a few times, to ensure that everything was cleared. It is possible that three clicks would clear the memory as well.
This is one of those habits that people acquired early on in the use of ...
90
Great question! This is an good case for microinteraction design.
Microinteraction objectives
In descending order of priority:
Provide clear affordance for user to place card/wallet on reader
Provide clear feedback that the user should hold the card on the reader until an outcome.
Since this is public transportation, provide blind- and deaf- friendly ...
89
The important thing is not so much which direction is right, but that you make it visually clear which direction is 'on'. This can be done by lighting up an LED, by an icon on the display, changing colors, etc. It just needs to be very clear what state the machine is and that this button will toggle the state. This is how single direction switches (buttons) ...
82
Excellent answers so far.
I would attempt to connect the dots between recording and red button like this:
Apart from the traditional warning usage, a red light has been used in many scenarios to represent on-going work - radio show room when on air, operation theater when operation is going on, etc. The reason behind that would be the same - it is highly ...
80
The underlying problem, as I think we all know, is that the tactile feedback you get with an incorrectly oriented plug is hard to distinguish from the tactile feedback with a slightly misaligned plug. Given that, your question can be reformulated as: why do many (most?) people mistakenly assume the orientation is wrong when they actually just need to keep ...
79
There's this humongous article called Keyboard Trivia that has collected many of the theories and stories. The summary of facts:
Touch-tone key pad was designed to mimic the rotary dial with the "1" on top and the 7-8-9 on the bottom, and AT&T conducted user testing to confirm that this configuration helped eliminate dialing errors.
By the time when the ...
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