It seems like the least efficient way to clean a table. One cup, one trip, round trip, when waiting five more minutes would allow the same person to carry all four at once and reduce the total number of trips by three quarters. Efficiency experts would wince. And yet, almost everyone has done exactly this, at some point, without being able to explain why, beyond a vague feeling that it was better to leave it aside. Psychology has spent the last decade coming up with a pretty precise explanation of what that feeling really is, and it has nothing to do with order or impatience. The bucket experiment that started the pattern was first documented in a 2014 study by psychologist David Rosenbaum and his colleagues Lanyun Gong and Cory Adam Potts, published in Psychological Science. Participants walked down an alley toward a platform at the other end, with a cube near the start of the walk and an identical cube much closer to the platform. When told to pick up either bucket and carry it the rest of the way, most people grabbed the closest one (the one that required them to carry it for a much longer stretch of the walk) rather than the furthest bucket, which would have meant a much shorter total carrying distance. This held even when the buckets were heavy enough that carrying one for longer would clearly cost more physical effort, and even when participants had already lifted both buckets beforehand and knew exactly how much that extra effort would be. Rosenbaum coined a name for this behavior: precrastination, the opposite impulse of procrastination, the need to complete a subtask as soon as possible, even at a real physical cost. What’s Really Buying the Effort The explanation that has held up best since then is what researchers call the cognitive load reduction hypothesis, tested directly in a 2018 follow-up by Lisa Fournier and colleagues, published in Attention, Perception, & Psychophysics. The idea is simple once explained: an unfinished task, even a trivial one like “remember to carry that other bucket eventually,” occupies a small amount of working memory while remaining unfinished. Finishing it early clears that mental space right away. In fact, the people in the study were trading the physical strain they would feel in their arms for a mental strain for which they would no longer have to pay rent. Given that trade, many people adopt it every time, often without realizing that they are making a decision. Two hundred million years of the same craft In 2015, psychologist Edward Wasserman performed a pigeon version of the bucket problem, reasoning that if precrastination reflects something as basic as reduced cognitive load, it should not be limited to food-carrying species. Pigeons pecked a touch screen through a three-step sequence to earn food, choosing between a path that delayed a change of location and another that eliminated it early. Birds almost always precrastinated, resolving the change as soon as the option appeared rather than waiting. The discovery did not go unanswered. A later team led by Thomas Zentall ran a version of the task structured more like Rosenbaum’s original alley walk than Wasserman’s touch-screen sequence, and got the opposite result: the pigeons procrastinated. Their argument was that Wasserman’s setup may have rewarded early switching for a more mundane reason (a conditioned association between the early cue and reward) rather than something akin to a pigeon clearing a mental to-do list. Whether the pigeons are really managing something like working memory here, or simply responding to reinforcement timing, remains an open question between the two labs. What is not in dispute is that the underlying compensation (paying a cost now to close a pending outcome sooner) appears in a species whose evolutionary line diverged from ours approximately 300 million years ago. Whatever precrastination is at a mechanistic level, it is obviously not a product of modern, overloaded human life. Where the cup fits The single-cup journey follows the same logic, although no one did a controlled study specifically on kitchen tables. Waiting to load four cups at a time means keeping “I still have to deal with those cups” as an open loop for the duration of the wait: a small, low-grade mental tab that must remain open until the job is done. Carrying a cup immediately closes that loop the moment you pick it up, at the cost of making three more trips later. The physical cost is obvious and easy to value: three extra walks to the kitchen. The mental cost that is avoided is much harder to see, precisely because avoiding it is what makes the open loop go away before anyone has to realize how much it was silently costing them. It’s not a personality trait, it’s a compensation. None of this means that every single-item trip is secretly optimal, and prolific precrastinators aren’t quietly winning some efficiency contest that the rest of us are losing. Four trips are still four trips, and there are many situations where waiting is actually the best decision. What the research does make clear is that impulse is neither a character flaw nor a tic worth correcting. It’s a readable and fairly universal trade-off that a mind constantly makes, choosing to expend a little more of the body’s effort in exchange for a little less of the mind’s, and for the most part making that trade-off without even putting it into words. The grocery bag version was tested directly. The cup scenario is an extrapolation of the cube data, but a close real-world analogue has actually been run in a lab. In a 2023 study in Psychological Research, David Rosenbaum and Julian Dettling had students carry doom balls (replacing shopping bags) between two containers spaced several feet apart, allowing each person to freely choose how many to carry per trip and how many trips to make. If people procrastinated, they would save the heaviest loads for the final trips, once the end was in sight. If they were precrastinating, they would advance the transportation and gradually reduce it. People took advantage of it at first. Participants carried more items per trip at the beginning of the sequence than at the end of the sequence, reflecting the cube resulting in a configuration that looks much more like a real task than an alley with two cubes inside. Half of the group also had to memorize and then recall a series of digits, adding a second unrelated demand to working memory, and the additional memory load pushed the pattern toward front loading, the direction predicted by the cognitive load reduction hypothesis. In other words, the cup scenario is not just a plausible-sounding extension of the original research. It’s close enough to a study that’s already been done.
