This is just a curiosity on my part, but I'm wondering if there's a name or studies for what I'm going to describe.

I've noticed in many UX scenarios, not just computer related, that when there's an alert or warning system for a situation that occurs somewhat rarely, a user's first reaction, rather than thinking that there's something wrong, as indicated by the system, is to think that the warning system itself is malfunctioning. I feel like the more rare the error, the more likely this mistake is to be made. A classic example is the "Check Engine" light in your car, where you reassure passengers that it's just the light that's stuck on. That one is seen plenty on TV and in movies. Even I made a mistake like that recently.

Does this psychological effect have a name? Is there data on what causes it, or even better, on how UX designers can avoid leading users into this trap? (Besides reassuring users that your warning system works really really well.)


4 Answers 4


When you design user interfaces, it's a good idea to keep two principles in mind:

  1. Users don't have the manual, and if they did, they wouldn't read it.
  2. In fact, users can't read anything, and if they could, they wouldn't want to.

These are not, strictly speaking, facts, but you should act as if they are facts, for it will make your program easier and friendlier. Designing with these ideas in mind is called respecting the user, which means, not having much respect for the user.

Quoted from Designing for People Who Have Better Things To Do With Their Lives by Joel Spolsky

But to answer your questions - let's take a look at Wikipedia and the article List of biases in judgment and decision making. Specifically we're interested in the Base rate fallacy which is the tendency to base judgments on specifics, ignoring general statistical information. Users (even programmers are users) see error messages, but neglect them since they know from experience that a lot of error messages can be clicked-through and no harm will be done. I can finish my task even if there are a few error messages along the way. The same goes for parenting when raising kids: Ignore bad behavior!

There are much more to read on this, but to answer your question - the effect would be called Base rate fallacy, if I understand the articles correct.

  • Actually I think it would be more like an inverse base rate fallacy. If we use wikipedia's terrorist example as an analogy, the error I describe would be due to underestimating the percentage of terrorists, and thus overestimating the probability that the alert was a false positive. I guess that still counts as the same fallacy though, if it doesn't matter in which direction the error is made.
    – Tesserex
    Feb 1, 2013 at 19:25
  • While not incorrect, I'm not sure that's the best name for this problem. It does apply - but it doesn't get to the core of what the base rate fallacy IS. The Base rate fallacy is when you misunderstand the chance of something happening because the chance of that thing happening is a subset of the chance of something else happening. Base Rate Fallacy occurs when people think that the likelyhood of being stabbed by a serial killer is HIGHER than the likelyhood of being stabbed. I'd discuss it as more of a type1/type2 estimation error, and the biases inherent in that. Apr 24, 2013 at 4:54
  • Base Rate Fallacy is probably the basis of "SNAFU"? Apr 24, 2013 at 5:30

"Don't do today what you can put off until tomorrow."

If the engine is still running then it can't be that important and so people doesn't want to be bothered with it. Stupid excuses have been made for far more important things than just a "Check Engine" light.

Toothache - "No need to see the dentist, the pain will go away by itself. Just give it time." Surprisingly many do just this. And if toothache doesn't get the attention it needs, do you really think a lit red light will get more attention?

If the light is red then you've done what you can...


It may also be a strange application of the fundamental attribution error.

The essence of the FAE is that people assume that they are not responsible for their failures.

People may simply assume that they're not responsible for the error - they blame the problem on the environment. In this case, they think that the error message is actually an error - because they would not have caused an error.

(The other side of the FAE is that we see other people failing due to personal problems, not environmental ones. If you saw someone dismiss this type of error, you'd be inclined to tell them that it probably WAS their fault the error message came up).

  • This applies to the check-engine light situation (user didn't have their engine checked at specified interval), but not to power plants (user ok, plant exception). The latter is maybe Base Rate Fallacy. Apr 24, 2013 at 5:29
  • The question is about receiving an error message, and interpreting the cause of that error message. I'm not saying it's definitely the FAE, it's just one way to explain the coginitive bias. On the other hand, the base rate fallacy is about interpreting the chance (not the cause) of a specific event. Similar, but not the same. Apr 25, 2013 at 0:22

Let's call it the Apollo 13 effect!

“It's reading a quadruple failure. That can't happen. It's got to be instrumentation.”

  • The comment with my name was not what I had written. And I could neither edit it nor post another comment on the question. So I deleted it. Feb 6, 2013 at 21:06
  • Your answer previously was converted to a comment instead of an answer because it doesn't answer the question, its just a subjective opinion not based on any data as OP requested. Do you have any info on where this term came from, or have you just decided on this term yourself?
    – JonW
    Feb 6, 2013 at 21:43
  • The idea behind what Nicolas has called the "Apollo 13 error" is part of complexity theory - which proposes that in any complex system, a breakdown is inevitable ... of course, that doesn't apply to the REAL problems of Apollo 13. We should probably call it the Murphy Effect. Or the Murphy Principle... Apr 24, 2013 at 4:50

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