Who do you think will win the Republican presidential nomination? Obsession with this question possesses the entire United States. Today a brief search on Google for “GOP primary prediction” returned close to 40 million results. Over the past few months, the news media has been a continuous spin cycle of talking heads, pontificating pundits, bleating politicians, and outraged citizens, all converging on the topic of who will eventually be crowned the Republican candidate for the American presidency. The amount of effort expended on this process is staggering—even though many people felt that the probable outcome was more or less obvious from the start.

Why is this such a compelling topic for us, both right and left?

One of the many frameworks for understanding the human brain is as a prediction machine. We evolved to be able to model, most unconsciously, complex future scenarios in our brain and to generate predictions about which of these scenarios is likely to occur. The fortune-telling aspect of our brains allows us to navigate our world successfully; we continuously create a model of the world around us, and then make guesses about what will probably happen next.

"When we watch everyday activity unfold around us, we make predictions about what will happen a few seconds out," says Washington University psychologist Jeffery M. Zacks. "Most of the time, our predictions are right.”

Zacks and his team showed college volunteers movies of everyday activities, such as washing a car and building structures out of Lego blocks. Zacks then stopped the movies and asked participants to predict what would happen next.

Based on when the action was stopped (such as right before a big change happened, or in the middle of an activity), people could predict what would happen next with an 80-90 percent accuracy. Zacks’ team found that the Midbrain Dopamine System (MDS) was very active in this process, providing feedback when unexpected events occurred. The MDS is an evolutionarily ancient part of the brain, which suggests that this system of prediction has been conserved by evolution, and is therefore quite important.

"It's valuable to be able to run away when the lion lunges at you, but it's super-valuable to be able to hop out of the way before the lion jumps," Zacks says. "It's a big adaptive advantage to look just a little bit over the horizon." Thanks to our ability to make mostly-accurate predictions, humans have managed to survive and thrive.

As Harvard neuroscientist Moshe Bar proposes in his work, the brain doesn’t wait around to be commanded to consciously make predictions. Instead it is proactive, continuously generating new predictions about the relevant future. This drive to predict applies not only to complex external events like elections, but is also fundamental to how we construct a mental picture of the world around us through our senses.

Our view of the physical world is made up of a series of intelligent guesses made at very low levels in the sensory processing modules of the brain. Evolution has found an efficient way to do this: by accessing memories early on in image processing to reduce the size of the search domain. For example, in visual processing, the brain starts with a blurry, low resolution version of a visual image—let’s say a circular shape—and already it knows that this could be an apple or a ball, but not a pen or a sheet of paper.

This makes image processing very fast, but also a matter of guesswork. The brain constantly uses its memory to assess what is likely present in various contexts and then create predictions about what we will experience. This makes novel items stick out, screaming for attention. All of this processing occurs extremely rapidly and unconsciously, knitting together a seemingly seamless mental model of the world around us.

Our need to predict runs very deep. Recent research by Nicholas Christenfeld and Jonathan Leavitt of UC San Diego’s psychology department even shows that—contrary to what most people believe about spoilers, well, spoiling a movie or book—unexpected, surprise endings actually reduce our enjoyment of stories, versus stories that don't end on an unpredictable twist. Presumably, the fact that we were unable to predict the ending in the former is experienced unconsciously as a failure by the brain.

Which brings us back to the GOP primary circus. The winner of the election will become the President of the United States, among the most important positions in the world. The outcome is obviously relevant to a huge number of people, industries, and countries. Because the brain is fine-tuned to focus its prediction efforts on important events like this, we cannot help but continuously wonder about the outcome and speculate what we think it might be. This urge turns out to be big business. There are numerous election prediction markets like Intrade in which buyers and sellers seek to profit by accurately forecasting election results. And websites such as Politico.com and fivethirtyeight.com hack out a permanent existence from our prediction mania.

As of this writing, there is still some uncertainty about who will win the GOP primary. If one of the underdog candidates like Newt Gingrich, Rick Santorum, Ron Paul, or Jon Huntsman wins, the Midbrain Dopamine System will light up and provide us with the unpleasant sensation of a prediction gone wrong. If it turns out to be Mitt Romney—the candidate that most markets have flagged as the front-runner for months now—it means that most of us will kick back and feel the satisfaction of another successful prediction. Then we can gear up for what I predict will be the yearlong circus of predicting the outcome of the general election.