Why would our evolutionary kin have pre-crastinated, and why do we humans and our pigeon contemporaries do so now? It is possible, as suggested above, that pre-crastination amounts to grabbing low-hanging fruit. If grain is nearby or if a bucket is close at hand, then it may be best to get it while it’s available. Another explanation is that completing tasks immediately may relieve working memory. By doing a task right away, you don’t have to remember to do it later; it can be taxing to keep future tasks in mind. Requiring people to delay performance of a task often worsens their performance of it. Yet, we doubt this is the whole story. Lifting a bucket doesn’t tax working memory very much, and it’s not obvious why directing the second peck to the future goal location would reduce the load on the pigeons’ working memory. A simpler account is that task completion is rewarding in and of itself. Tasks that can be completed quickly woo us more than tasks that must delayed. All potential tasks, or their underlying neural circuits, compete for completion. Neural circuits for tasks that get completed may endure longer than neural circuits for tasks that don’t.

Another benefit of completing tasks as soon as possible is to provide us with as much information as possible about the costs and benefits of task-related behaviors. Trial-and-error learning is the most reliable way we discover what does and doesn’t succeed in everyday life. Such learning can even prompt practical behavioral innovations. Given these benefits, it may be better to gain experience from several trials than only a few.