gregory schraw, theresa wadkins, and lori olafson in 2007 proposed three criteria for a behavior to be classified as academic procrastination: it must be counterproductive, needless, and delaying. steel reviewed all previous attempts to define procrastination, and concluded in a 2007 study that procrastination is "to voluntarily delay an intended course of action despite expecting to be worse off for the delay." sabini & silver argued that postponement and irrationality are the two key features of procrastination. delaying a task is not deemed as procrastination, they argue, if there are rational reasons behind the delay.