In one experiment, half of the participants (students and staff at the University of Chicago) were given a task to get them thinking about dates in the near future; the other half simply sorted numbers. Then, all participants had to plan a hypothetical birthday party for a friend in seven days' time. So, if they were participating on a Tuesday, the party would have to be next Tuesday. When asked to rate whether they would start planning for the party now or later, participants that had done the date-sorting task were more likely to say they would get on it, stat.
In a another experiment, participants were asked to imagine that a task of theirs had to be completed in five days' time. For some, the five days were within the same calendar month (i.e., September 25-30) but for others, the due date spanned the month change (i.e., September 26 to October 1). When asked when they would start working on the task, those with a different-month due date were less likely to get down to business — possibly because October "felt" like it was far away.
So, all of this suggests that one of our big issues is actually seeing deadlines for what (and when) they are. When a barrier, however imaginary, between present and future is put up, we feel like we have all the time in the world — even when logic tells us we still only have five days.
Another big issue is what's known in behavioral economics as "dynamic inconsistency." This is simply the idea that our priorities change over time, which means we're not great and predicting what will be important to us in the future. For instance, in one of the best known examples of this, researchers asked participants which movies they would want to watch now vs. at a later date. Almost all of the participants preferred to watch a lowbrow movie (such as The Breakfast Club) immediately, but said that later on they'd prefer a highbrow one (such as Schindler's List).
What does this mean for the average list-maker? Well, if you're given a deadline, do everything you can to make it seem like it's a priority now: color coding, stickers, lots of arrows and post-its — whatever it takes. And, if you're the one creating the deadline, it's best to avoid spanning weeks or months. So, basically, we'll be plowing through our Netflix queues ASAP, because we certainly won't want to watch that stuff in October. What's October?