Why does a looming deadline make you suddenly want to work?

Because, according to temporal motivation theory, time is part of the math of motivation. The theory, developed by the psychologists Piers Steel and Cornelius J. König, treats time as a critical motivational factor: the more delay stands between you and a task's reward, the weaker its pull. As a deadline approaches, that delay shrinks and motivation rises, and some researchers argue the perceived value of the activity grows exponentially as the deadline nears.

In its simplest form, the theory writes motivation as expectancy times value, divided by one plus impulsiveness times delay. Expectancy, also called self-efficacy, is the probability of success; value is the reward the outcome brings; impulsiveness is your sensitivity to delay; and delay is the time to complete the task. Expectancy and value sit on top of the fraction, so raising them raises motivation. Impulsiveness and delay sit on the bottom, so a long delay drags motivation down, and shrinking it lifts the whole fraction.

The theory's own example is a student given one month to study for a final exam, who enjoys socializing but needs a good grade. At the start, the reward of studying isn't immediate, so the motivation to study is lower than the motivation to socialize. But as the study period shrinks from several weeks to several days, the motivation to study overtakes it. The exam is the same exam; only the delay has changed.

Steel and König built the theory to be broad, because no single theory could explain motivation on its own, so it borrows from expectancy theory, hyperbolic discounting, need theory and cumulative prospect theory. The researchers Schmidt, Dolis and Tolli suggest it may help us understand how time, and particularly deadlines, steers where we put our attention.