Forgiving Text Entry

Examples:

Someone's name
Phone number, possibly with country code and/or area code, possibly without
URL text field on most browsers

Context: The user should enter information, as on a Form or in a Composed Command, that may be formatted in any one of several ways.

Problem: How does the artifact indicate what kind of information should be supplied?

Forces:

Physical and cultural constraints on the allowable input prevent unnecessary interpretation errors from being made.
Too much constraint can be annoying to the user.
The user doesn't need the cognitive burden of figuring out what specific format is acceptable.
Users are diverse, and will likely have different cultural or personal preferences for formatting various pieces of information (especially things like names, dates, and times).
Both computers and humans -- depending on who's interpreting the entered information -- are good at figuring out what a given text entry is intended to be, if it even vaguely resembles some accepted format.

Solution: Allow the user to enter text in any recognizable format for that context. Be forgiving of formatting idiosyncracies, formatting mistakes, or recognizable "typos." Place the burden of normalizing the input (i.e. making it fit one format, for use or storage) onto the recipient of the information, whether that be a human or a computer.

In theory, it's difficult to make a computer do this correctly, but in practice it often turns out to be not so bad. To illustrate, consider the fact that most Web browsers these days allow URLs to be entered in several different ways. An URL such as "http://www.foo.com" can be entered that way, or as "www.foo.com", or even just "foo". There is enough context for the browser to figure out what the full URL ought to be; there's no point in making the user type it all in!

Resulting Context: Good Defaults may let the user look at the default value, judge it to be OK, and move on without even bothering to set the value; it may also help suggest what kind of input is allowed.

Comments to: jtidwell@alum.mit.edu
Last modified May 17, 1999