David Biello in Scientific American:
I am a moderate procrastinator. Even when I believe that I would be best served by finishing a task (say, filing this story), I will occasionally put it off in favor of some short-term reward (like a much needed caffeine fix). This tendency on my part to delay what is in my long-term interest can now be explained by a simple mathematical equation, according to industrial psychologist Piers Steel of the University of Calgary.
Steel developed the equation U = E x V / I x D, where U is the desire to complete the task; E, the expectation of success; V, the value of completion; I, the immediacy of task; and D, the personal sensitivity to delay, as a way of mathematically mapping a given individual’s procrastination response. So, for example, my desire to finish this article is influenced by my relative confidence in writing it well and the prospect of a paycheck as well as a looming deadline and my inherent desire to go home at the end of the day. “You’re more likely to put something off if you’re a very impulsive individual,” Steel says. But, “if you only work at the last minute, time on task tells.”