Designating required vs. optional input fields
Thomas S. Tullis, Ana Pons · 1997
This paper describes a study comparing different techniques for visually distingishing required from optional input fields in a form-filling application. Seven techniques were studied: no indication, bold field labels, chevrons in front of the labels, check marks to the right of the input fields, a different background color, grouping them separately, and a status bar indication. Performance and preference data were collected. In general, we found that the two worst methods were no indication and the status bar. The best method was separate groups.