Why do people clear the screen multiple times when using a calculator?

  • I've noticed that most people when using a real or a virtual calculator, they hit the Clear button multiple times when clearing the screen (even though hitting it once is enough), so I started wondering: is there a flaw in the calculator's design that compels most people to do that?

    What makes them trust the button less than the other buttons? Is there some sort of feedback mechanism that's missing? Even if it's just a habit, how does one end up developing it?

    I usually do this with Ctrl-C (copy to clipboard) a lot. Sort of, I really, really, really want this copied.

    @LarsTech I do that too, but usually because the program/hardware I am using at the time has 'skipped' copies before. Whether due to bugs, slowness, or rogue neutrinos, I could not say!

    It's an interesting habit, maybe it needs a name like Clearing Anxiety or Copy Anxiety :)

    this is the same as pushing the button multiple times to cross a pedestrian zebra

    @LarsTech: IMO that behavior (I do it too) is caused by bad interface design, where hitting a key combo doesn't produce any visual feedback. On Mac OS X, for example, the menu corresponding to the key combo flashes briefly when you hit the key combo.

    probably the same reason people hit the **ESC** in Vi/Vim multiple times to make really sure they are not in insert mode anymore.

    @bizso09 The pedestrian crossing button is a placebo

    The same happens with the ATM

    This reminders of of Right Click on Desktop and select Refresh :) (applies to Windows users)

    @Patrick McElhaney: How did you arrive at that conclusion? It may have been true at one stage, but traffic control has evolved and I can assure you there are now many traffic lights where the light won't change **unless** I press the button. And remember: try this at a time when there is no other traffic, as traffic going in a direction which frees up the one you want may change your light as well.

    @MarjanVenema Okay, *some* of the buttons are placebos. http://www.nytimes.com/2004/02/27/nyregion/27BUTT.html My intent was more to point out an interesting fact than to counter bizso09's claim. (BTW, in Charlotte, NC, where I live, there are a bunch of new ones that as far as I can tell don't do anything.)

    For the same reason that people push the elevator/lift button multiple times. Oh, wait, that's because elevators are pneumatically controlled and each press of the button pushes a little more air through the tubes which makes it move

    I do it with Ctrl-S. Even when it's a mouse-click Save button. I've seen many others do this too.

    @Lars - my keyboard at work does not always handle the ctrl-c so I have to click several times unless I have word running which gives visual feedback

    Once to clear the calculator screen, and a few more times to clear your mind :)

    I find myself doing this with F5 too to refresh a webpage...

    I think this article answers this question the best: Why calculators need a better user interface. It also provides solutions to other calculator problems that are worth mentioning.

    Thats a very good question. I do the same . !

    My reasons ( my calculators had really rubbery and stiff buttons ) pressing once often didn't reset it. Esp, when you're not paying attention. Usually when im resetting i'm moving away my attention to something else. And to be sure it do get cleared i press it multiple times. Now it's just a habit that confirms i am onto next step to my brain. Short: History with bad calculators.

    Also, i do this with lot of other things...when i want to make my intention clear. To them and to myself and don't care about anything until ive done this. For example in language i'd say "no no noooo ok" or computer power off button, or opening app in mobile by multiple consecutive touching.

    @PatrickMcElhaney Where i live in the NE, there are only functional buttons for crosswalks. The ones that always switch with the light never even have buttons installed. Those are prett much only in the downtown area with heavy pedestrian traffic. All other ped cross signals in the city won't ever activate without pushing the button.

    `CTRL` + `X` has a visual result while `CTRL` + `C` doesn't, which sometimes fails because of the keyboard being bad or not pressing the keys correctly.

  • (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 be no obvious indication of the current state of the calculator (i.e. is it reset and waiting for a new operation or in the middle of one?) If you want to start anew without having to remember which button is which or how a specific calculator works, you can simply press a couple of times on all cancel buttons and that's an habit many people kept from that time.

    Windows calculator

    That's a pretty good explanation for those who have used such calculators, but many people (like me) haven't, yet they still have this habit. How can that happen?

    Yes, that CE / C button duality always drive me crazy, I newer know which one to push. So I push both and to be sure, push them several times :-)

    Many new calculators, particularly desktop 10-key calculators have this operating mode so I don't think it is really an issue of old calculators vs new calculators.

    Ah, *that's* what the CE button is for...

    @Mashhoor The behaviour pressing the clear button multiple times may be some kind of social inductance. I mean; most likely the behaviour has been transferred from users who had CE on their calculators over to users who haven't. Meaning you saw someone do it, and that's why you do it yourself (the same learning process for observing traffic and doing the same while you drive a car).

    Yeah I do this. Still have no idea, I even click multiple times on software calculators.

    The first calculators I used had a combination "CE/C" button; press it once to clear your last entry, press again to fully clear. I press C twice out of habit.

    +1. I even find myself pressing the shortcut keys for both of those buttons on the (older) Windows calculator: Del + Esc

    To make it more confusing on calculators in the UK "CE" stands for "Clear Everything". That messed up my sums more than a few times.

    It's like with vi and pushing esc several times :)

    I had no idea what you were saying, and then I saw the freehand circle. It makes much more sense now! +1

    It's probably for the same reason people shake polaroids. That actually interferes with the picture clarity. But it made sense back in the Land camera days when you peeled wet layers apart and wanted to dry the photo. It's a cultural appendix.

    While this is a wonderfully colorful explanation, I'm certainly not convinced this is more convincing than other explanations given here. This reminds me of how false etymology forms. Good stories get +1 votes, better explanations aren't always as compelling. :)

    @Mashhoor, it's for the same reasons people shake polaroids: it was once to dry off the photo paper when you peeled the photo apart, but since then is useless gesture.

    In Australia most calculators were labelled "CE" and "AC" for _Clear Entry_ and _All Clear_ respectively.

    You must upvote this comment if you never press CE, and always restart your entire calculation any time you make an entry mistake.

    Interesting choice of number to display...

    The C/CE duality has gotten me so confused throughout my life that to this day I turn the calculator off and on again. To make sure. i'm capable of removing the batteries, out of sheer paranoia

  • 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 the calculator is in the middle of an operation or not. So we press Reset a bunch to make sure.

    Plus, many of us have gotten burned by starting a new calculation while the calculator was still in another mode, and gotten a totally unpredicted result. So we press reset a bunch to be sure.

    Some calculators are better at this. For example the Win7 calc shows you prior operands. Some smartphone calcs show operands in vertical lines, and clear the screen when you press reset. Perhaps an even better enhancement would be to show the background screen in white if the calculator is truly reset, and colored if it's in the middle of something.

    But there will always be the tendency to push the button a bunch of times, because better safe than sorry! ;)

    I pressed the upvote button several times.

    @Patrick, odd or even number of times??

    This is exactly why I hit Ctrl-C 5 times every time I try to copy but I only hit Ctrl-X once when I want to cut.

    Similar reason why people like to push elevator buttons multiple times, It goes faster :)

    I agree with the psychology of this answer the most. It is like the physical process of cleaning: we sweep back-and-forth with a cloth, broom, etc. many times in order to ensure we 'did not miss anything' that our eye cannot or did not see!

    Not only calculator. Here are common 'useless repetitive' habits I found around my office : refresh windows screen (F5), double click a hyperlink, copy (ctrl+c), Hung up phone using "flash" button, or pushing the button where the phone handle rest (don't know what this button called), refreshing a web page in a (very) slow network. It's a matter of habit and imitating people.

    @PatrickMcElhaney You'd just be alternating the state!

  • 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 technology, which has continued despite the change in the technology.

    And it is an interesting UX question, because the reality that clicking it multiple times has no additional effect does not change the perception. There are other cases of this, I am sure, but we actually just need to understand that this will happen.


    There is also the sense of clicking and clicking while I make the decision to move onto something else. It is not then based on habit, but just an attempt to reflect what is going on internally, that I need to clear my mind before I move on.

    Maybe if I press the door close button 50 more times this elevator will go faster...

    Schroedingers: But I've never used any calculator like that (that reqiores multiple clicks to clear), yet i still developed it. Same thing applies to everyone I've asked about this after reading your reply. Also some young people developed this, which is really strange. Ben: lol yea people do that as well, but maybe out of frustration?

    Oh I also forgot to add that I saw my young niece the calculator, and when she presses the Clear button, she presses it really hard then continue using the calculator. This mistrust is strange.

    But you may have picked it up from others. But there is that sense that we need to be absolutely sure.

    +1 Yes, this. Not the fact that there are two clear buttons (C and CE), but that on many older calculators pressing C once cleared the current entry (CE), and pressing it twice cleared the entire calculation. I still have this muscle memory, and still press the C key twice, just because I don't want to have to think about it.

    Wow, I've been using windows calculator for years and _never noticed_ that "clear all" and "clear entry" were separate buttons. Note that the iPhone's built in calculator _does_ exhibit this 2 presses to "clear all" behavior, so perhaps more of us have used this type of calculator than we realize?

    This. The cheap four-function calculators with a combined C/CE key are what I grew up with in the early 90s.

    A once-is-good, twice-is-better feature is contagious to the brain. My Mercury Sable car key fob **unlock** button operates like this: push once to unlock the driver's door, push twice to unlock all four doors plus the trunk. I routinely hit it twice whenever I want to unlock anything. I also push the unlock button inside the car 3-7 times (bugs the crap out of my kids) whenever I want to unlock something, even though it doesn't even have that feature, and once is always enough. Thinking also of some lab rat pleasure-lever experiment gone wrong. (Wrong for the rat, great for science.)

    @BenBrocka If I keep jamming on the pedestrian crossing button, the lights will surely turn red faster.

    `It is possible that three clicks would clear the memory as well.` - Correct. Some calculators had a couple of M buttons (like `M+`, `M`, and `MC`) that allowed you to save the result of an equation (`M+`, add to memory) and, for example, use it as the divisor in the next equation. `MC` would clear the remembered value and nothing else, but so would `C / CE` if the entry and equation were already cleared - so, 3 taps to clear all 3 levels

    For what it's worth, I can't recall ever using a physical calculator that didn't require two presses to clear all, but clearly some do exist. I suppose from a UX perspective it'd be better to have two distinct buttons so that users don;t unintentionally clear all when they only wanted to clear the last entry. Either that, or offr some sort of 'undo' button to undo whatever the last action was.

  • Since there is no negative outcome to hitting the button multiple times, the question becomes really more of, "why wouldn't you hit it more than once?"

    It would only take using a calculator with this behavior one time to create this behavior.

    Think of it this way....

    A person who has never used a calculator that works this way, one day uses a calculator that does. After some initial frustration, he learns that to clear he must hit the button twice.

    He continues the rest of that day. Every time he hits the button only once his calculations are messed up (negative feedback) every time he hits it twice his calculation are correct (positive feedback)

    The next day he uses a calculator that doesn't do this. However the behavior is already learned. But now whether he hits the button once or twice doesn't matter: both give positive feedback. Since both give positive feedback there is nothing to promote unlearning the behavior.

    Now we continue on days or weeks later, he uses different calculators but doesn't really differentiate them. Hitting the button becomes like touch typing, a simple learned response.

    When I type I don't think of the letters that I type or even how I move my fingers as I type. I just think of the words and brain an my fingers know how to make the letter appear on the screen. When I hit clear on a calculator I don't think "find the clear button, press the button x number of times" ... no I think "clear" and my fingers press clear (however many times they do.)

    Now here is the really interesting bit. Say after awhile he does stop hitting the button twice. Ok well no problem on his normal calculator. However every time he picks up one of those other calculators, he's going to get negative feedback and the double tap behavior will again be reinforced.

    Since he doesn't really differentiate these calculators when he picks them up, eventually his brain will determine that the cost in terms of effort of not hitting the button every time is greater than hitting the button unnecessarily. So... he just presses the button twice all the time.

    "Since there is no negative outcome to hitting the button multiple times, the question becomes really more of, why wouldn't you hit it more than once." Just thinking to myself all the other things that might apply to, for example: Turning a door knob twice to make sure it's locked. With that sort of logic, why stop at two times, I mean maybe the second turn unlocked the door, right?

    @blunders Yep all sorts of things, but you might be thinking of it a bit wrong. I'm talking about an instance of positive or neutral feedback with no negative feedback. Actually your example of a door that unlocks when your turn it the second time is a good example of what I'm talking about. The behavior of the door is a great example of negative feedback. 1st time locks the door, 2nd time unlocks it.. therefore don't turn it a 2nd time if it want it locked. I do ~try~ to set my deadbolt twice but it doesn't turn the 2nd time, now if it gave me an electrical shock the 2nd time...

    My point is that some people are obsessive–compulsive, and no matter how much feedback they get, they'll almost insanely attempt to see if something different happens a second time around. This is not an interface malfunction, it's a user malfunction.

    @JustinOhms You're very correct! The way this happened to me (and I would guess, many) is that one of my first pocket calculators had really crappy buttons and would often need a firm, long press to ensure it worked. The failure of a number or operation key to work produced immediate and obvious feed back, but the clear key failing is just as you described in your answer. +1

  • I'm going to departure a bit from the current line of thought. Back in the typewritter days, I remember seeing my dad's accountant typing really fast on the machine. Whenever he paused for any reason, he kept pushing the "shift" button several times in a row.

    He knew pressing that key didn't do anything, and that was exactly the reason he pushed that key... it didn't do anything but kept his fingers busy, or gave the impression that he was busy, or simply because it helped him to keep that rhythm, who knows...

    My claim is that some people will press the CE several times just because they know it won't do anything, and that's it.

    On my typewriter, shift *did* do something, namely remove the caps-lock if it was activated. So it could be the same issue: to make sure the typewriter is in "normal" mode, a shift "is always good". Same as hitting Esc before any operation in vim, instead of looking at the (rather poor) mode feedback.

    This is an excellent observation, I sometimes also hit on the table or something when I'm concentrated at something and don't want to lose the line of thought.

    giraff, I understand the functional use of the shift, but in my observation, the accountant (in fact I've seen the same behavior in other people as well) would type shift in rapid continuous succession for about 2 or 3 seconds while he was checking what he had just typed. It almost seemed like he didn't want "to turn the engine off"

    Similar to Starcraft players who are pressing things just to keep fingers occupied and blood flowing etc: http://gaming.stackexchange.com/questions/21647/whats-with-all-the-clicking-the-pros-do-in-the-opening-minutes-of-starcraft-game

    I thought I was the only one. I frequently get to see the "Do you want to turn on Sticky Keys?" dialog because of this habit.

    I think he hit the Shift key in the typewriter to prevent it from starting the screen saver or from getting the screen (pardon, the paper) blank.

    Nice one… I don't think that it has to do something with pushing clear (I myself push it for some other reasons), but it's a great example on how people are keeping themselves in the Flow (a busy, entranced state of mind, described by Csikszentmihalyi)

  • It is low-cost fidgety action (on user's part) combined with a device that offers low levels of feedback for that action. Such a combination makes you want to repeat that affirmative action.

    I find myself using ctrl-c multiple times for the same piece of text. I would do that much less often if MS Word's clipboard manager were open or I had a sys-tray app that blinks every time I use ctrl-c.

    As another example, I face conversations where I am disinterested and the other too enthusiastic. He may repeat certain phrases ("job security", "future", "career") to compensate for my disinterestedness. But if I repeat that phrase in front of him, I find that he moves on.

    Test for my hypothesis: would a user repeatedly press that button if it gave a satisfying click, or the screen blinked once?

    +1 Good point view. However these "low-cost fidgety action" have a name: compulsions, and they're **not** necessarily symptom of a disorder. And to answer your last question, sometimes yes, sometimes no. I've seen a friend of mine martyring my poor Casio even if it blinked after clicking the clear button... And I've seen myself clicking Ctrl-X more than once when cutting files in MS Windows, where they become 'translucent' (so there's a feedback)

    Another example of low-cost fidgety action is a crosswalk button. I've seen people hit that button ten times in rapid succession. I'm not sure if they were getting their anger out or just wanted to be 9x sure that the button was pressed

  • Slow feedback can cause this. It makes the user feel like the button is broken and needs to be pressed again or harder, which would work in the real world.

    Did it work? Did it really work? Really?

    ...also, just general frustration. We're used to some button-presses being idempotent (as with an elevator): once pressed, additional presses are a no-op, so if people are bored and waiting (think: crosswalk buttons), or annoyed with the interface, they may hit it a bunch of times.

    Repeated presses may also be used for emphasis--"Clear, dammit!"--or for efficacy--in conversation, we're used to having to work very hard to 'erase' a previous statement.

    Finally, a button press takes less time than it takes for the user's mind to switch tasks, so while the mind is switching, just keep pressing 'clear' to keep the hands busy. Otherwise you're gaping at a blank screen and forget what you were doing.

  • These people, I have to admit myself included, have had experiences before with calculators that if they hit clear or 'C', and do a math expression, the result is incorrect. So in their mind, they hit the clear button several times to "totally clear" the contents before proceeding.

    Have you also noticed that they will hit the 'C' and 'CE' buttons over and over again, not just 'C'? They are not sure which one does which, so they just slam on both of them until they feel satisfied.

    Agreed, sometimes I've clicked them in the past just to make sure I've cleared the memory contents.

  • Some of the credit-card sized, solar-powered calculators (without a battery backup), which were all the rage in the early 1990s, didn't always reset to the initial state completely when under a low-light condition, after pushing the C (clear all) button, and thus would behave unpredictably after such "incomplete reset" - I think some of the registers were not cleared due to very low power provided by the small solar panel. For this reason, it was customary to press the button multiple times - which prevented the problem.

    Also, some models of the calculators had the buttons combined into one: CE/C - first push would erase the last entry, second would reset to initial state.


    The C/CE issue is already mentioned in this answer

    @ChrisF: True. However, I haven't seen the physical reset issue mentioned in any other answer.

    My understanding is that while calculators are made of of latches which are each supposed to be either "high" or "low", reducing the voltage on a latch just the "right" amount before reapplying power may leave it in an intermediate state. Latches which are in such states may draw more current than latches which are cleanly high and low, and this current draw may "drag down" the supply voltage below the level required for reliable operation. Pushing reset once will kick any latches that were not cleanly high or low, and ...

    ...will allow the supply voltage to rebound within a half-second or so, but the fact that the voltage was low when the button was pushed may cause the calculator to have not reset cleanly. A second push after the voltage has rebounded would resolve things. Given that many people have sometimes used calculators with a CE/C button, pushing twice as a matter of habit is easily explainable as either occasionally-necessary behavior, or a consequence of seeing others do it.

  • I'm going to answer this question with another question: why do people press the elevator button multiple times, some even if a light indicator turns on immediately after the first time? You see this often with old people. I think the answer is psychological.

    Most people by now are pretty accustomed to the way electronics and digital circuitry works: things are usually either on or off. Pressing the button elevator multiple times won't make it come faster, resetting the calculated multiple times won't make it reset "harder". Still, this model of interaction with hardware relies on an assumptions that things work as expected. I believe most of us still have a lot of analog habits, though, and in the analog world you sometimes have to apply yourself a bit more to get stuff to work. We know that sometimes you have to jiggle a key so the lock works and sometimes you have to hit the fan so it stops making a noise.

    It doesn't necessarily mean that things have to malfunction for us to give them an "analog" treatment. Sometimes we perceive things as just a bit more complicated than we'd like them to be, and in the trade-off between not being sure whether the elevator's button has registered the signal (which makes us feel worried about waiting like idiots for something that's not coming) and between just one more push of a button, the latter is often the more cost-effective choice.

    So, to summarize, even digital things sometimes work in unexpected ways (due to malfunction or hidden complexity) and when faced with this uncertainty many people fall back to their analog habits of giving HW an extra nudge to make sure it knows what they want from it.

License under CC-BY-SA with attribution

Content dated before 7/24/2021 11:53 AM