A user error is an error made by the human user of a complex system, usually a computer system, in interacting with it. Although the term is sometimes used by Human Computer Interaction practitioners, the more formal human error term is used in the context of human reliability.
User Error and related phrases such as PEBKAC ("Problem Exists Between Keyboard And Chair"), PICNIC ("Problem In Chair Not In Computer"), PIBCAK ("Problem Is Between Chair And Keyboard") or ID-10T error ("Idiot error") are also used as slang in technical circles with a derogatory meaning.[1][2] This usage implies a lack of computer savvy, asserting that problems arisen when using a device are the fault of the user. Critics of the term argue that the problems are caused instead by a device designed in such a way that it induces errors.
The term can also be used for non-computer-related mistakes.[1]
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User errors can be divided into two distinct categories. In the first the user enters data or instructions which are valid for the system, but not the ones intended. For example in a system intended to add two numbers together the user may enter "2" and "3" when they intended to add "2" and "4". The system returns the answer 5, which is the correct answer for the data input, rather than the answer "6" which the user expected. The second category of user errors is those that can be detected as invalid by the system. In the above example this might be entering "A" as one of the two numbers to be added.
These two types are not necessarily easily distinguishable. For example, asking an autopilot to fly at a height below ground level would be considered an error, but might not be detectable by the autopilot.
Common examples of user error include:
Joel Spolsky points out that users usually do not pay full attention to the computer system while using it.[3] He suggests to compensate for this to make usable systems, thus allowing a higher percentage of users to complete tasks without errors:
"If you sit down a group of average users with your program and ask them all to complete this task, then the more usable your program is, the higher the percentage of users that will be able to successfully create a web photo album. To be scientific about it, imagine 100 real world users. They are not necessarily familiar with computers. They have many diverse talents, but some of them distinctly do not have talents in the computer area. Some of them are being distracted while they try to use your program. The phone is ringing. WHAT? The baby is crying. WHAT? And the cat keeps jumping on the desk and batting around the mouse. I CAN'T HEAR YOU! Now, even without going through with this experiment, I can state with some confidence that some of the users will simply fail to complete the task, or will take an extraordinary amount of time doing it."
Experts in interaction design such as Alan Cooper[4] believe this concept puts blame in the wrong place, the user, instead of blaming the error-inducing design and its failure to take into account human limitations. Bruce Tog Tognazzini describes an anecdote of Dilbert's creator Scott Adams losing a significant amount of work of comment moderation at his blog due to a poorly constructed application that conveyed a wrong mental model, even though the user took explicit care to preserve the data.[5]
Jef Raskin advocates designing devices in ways that prevent erroneous actions.[6] Don Norman suggests changing the common technical attitude towards user error:[7]
"Don't think of the user as making errors; think of the actions as approximations of what is desired"
On the previous examples, some suggested approaches to reducing user error might be:
| Error | Design solution |
|---|---|
| Typing password with caps-lock | Providing clear feedback that caps-lock was activated while typing the password, helping to avoid a mode error. Many modern OS systems can provide an audio response to using the Caps Lock, with different tones for activation and deactivation. Alternatively passwords could be made case-insensitive, thus removing the possibility of a mode error and enhancing usability at the cost of security. |
| Unplugged device | A prominent LED to show the on/off status of the device. However, many devices have this already, and do not necessarily eliminate this error. |
| Message dialog for destructive operations | Avoiding the use of a modal window to warn of a destructive operation (using a persistent warning instead), or provide an undo command to make the action non-destructive. |
| Unplugged network cable | Showing the connection status in a clear way, including a report with the causes for a lack of connectivity and a message on how to resolve it (i.e. plug in the cable). |
| Errors caused by session timeout | Warning that sessions do timeout after a period, and saving all the user actions performed before the session expired. Alternatively, an auto-redirect to a holding page explaining the error on timeout would prevent attempts to continue work on invalid sessions. |
| Erroneous data entry | Performing automatic data validation on input. |
Several terms like PEBKAC or and ID10T error are often used by tech support operators and computer experts to describe a user error as a problem that is attributed to the user's ignorance instead of a software or hardware malfunction. These phrases are used as a humorous[8] way to describe user errors. A highly popularized example of this is a user mistaking their CD-ROM tray for a cupholder, or a user looking for the "any key". However, any variety of stupidity or ignorance-induced problems can be described as user errors.
Phrases used by the tech-savvy to mean that a problem is caused entirely by the fault of the user include PEBKAC[9] (an initialism for "Problem Exists Between Keyboard And Chair", also PEBCAK or PBKAC[10]), PICNIC [11] ("Problem in Chair, Not in Computer") and EBKAC ("Error between keyboard and chair").
In 2006, Intel began running a number of PEBKAC web-based advertisements[12] to promote its vPro platform.
ID-Ten-T Error[13] (also seen as ID10T and ID107) is a masked jab at the user: when ID-Ten-T is spelled out it becomes ID10T ("idiot"). It is also known as a "Ten-T error" or "ID:10T error". Historical use (circa 1995) includes phone tech support personnel instructing the user/customer to place the line "id=10t" in their config.sys file as a warning to future tech support personnel. The UserFriendly comic strip presented this usage in a cartoon on February 11, 1999.[14]
In United States Navy and Army slang, the term has a similar meaning, though it's pronounced differently:
The networking administrators' version is referring to the cause of a problem as a "layer 8 issue". The computing jargon refers to "wetware bugs" as the user is considered part of the system, in a hardware/software/wetware layering. The automotive repair persons' version is referring to the cause of a problem as a "faulty steering actuator," "loose nut between the steering wheel and the seat," or, more simply, "loose nut behind the wheel." Similarly, typewriter repair people used to refer to "a loose nut behind the keyboard."
The broadcast engineering or amateur radio version is referred to as a "short between the headphones".