Seeing Red - Why Red Is a Good Contrasting Color for an Effective User Experience

When designers create user experiences, red is the color most often chosen in interface design to draw attention and signify an alert or warning. A message in red text might say, “Email is a required field” or “Invalid username or password." Sometimes red is just used to draw attention. The question becomes, is red especially suited to this task, or just a handy contrasting color that is not often used for primary interface elements?
