How our daily predictions serve us

Dr. Jeff Zacks


If you predicted that this article would be about medical research, good for you. But could you have guessed that the subject plays in a saxophone quartet made up of all psychologists?

Probably not – because you couldn’t know that with the clues you had.

Jeff Zacks is one of the few researchers in the country studying the process that allows the brain to predict when the bus will come, whether we can cross the street fast enough to avoid getting hit or who is likely ringing the doorbell.

“At the end of the day, we have to behave in an adaptive fashion to protect ourselves from bad stuff and to take advantage of good things,” says Zacks, 41. The secret? “To make our behavioral choices more effective, we need to maintain a clear representation of what’s happening now.”

Zacks is the lead author of a paper on this research that will be published in December in the Journal of Cognitive Neuroscience. He made time recently to talk about his work.

How did you get interested in this field?

My team got excited through our interest in how ongoing experiences are segmented into meaningful chunks. One hundred years ago, William James said that stream of consciousness is not a continuous flow, a drifting from one thought to the other, but thought influenced by discrete events. He likened it to the joints in a bamboo stem.

How were your studies set up?

We asked people to watch movies that show chunks of meaningful events, such as washing clothing or a car. We stopped the movies at different times and asked people to predict what would happen next. Then we started looking at what was going on when people perceived that one event ended and another began.

Give us an example.

There are points in the movie when stuff changes – maybe the person you’re watching takes on a new goal. Or it can be something at a lower level, such as the direction of a vehicle changing. We started thinking about why these changes are associated with event boundaries and what function they serve.

What function do they serve?

It’s adaptive to look over the horizon and respond to what’s about to happen rather than wait for it to come to pass. When we try to anticipate the near future, as long as our predictions come true, then our representation of the moment is a good one.

And if not?

If our predictions misfire, we need to update the representation, figure out what is happening.

Is this remarkable?

I’ve always wanted to know how we do the crazy things people can do. For instance, what Albert Pujols does is impossible. The ball takes only a few hundred milliseconds to travel from the pitcher’s hand to the plate, and Pujols has to calculate the timing within a few milliseconds and the location within a couple centimeters. That’s amazing.

What other things come to mind?

Some people can play a fantastic game of chess, drawing on a library in their heads of thousands of games played before. They do this rapidly, without awareness in lots of circumstances. That’s extreme performance, as with Pujols, but when it comes to driving to Colorado without getting killed or even balancing a checkbook – we also do this without thinking about it. Other animals can’t do this.

As a child, did you predict this future for yourself?

I grew up in a suburb of Lansing, Mich., in a home with the typical Jewish love of education. In college, I thought I would study American literature and culture, but I drifted into the philosophy of mind –thinking, judging, believing. I also was interested in computers. Then I got excited about the topic of mental life, but not in principle as much as in how people do what they do.

What are the medical applications of your work?

The two main medical applications are in neurology and psychiatry. We’re looking at people with post-traumatic stress and people with dementia. Down the road, this work may lead to cognitive tests we can use to diagnose changes in brain function.

What surprised you about the research?

I was surprised how well people did overall. We tried to make the tests really hard, and still people got 80 to 90 percent of the predictions right. That reinforced for me how well optimized the predictive mechanism is.


HealthWatch – Jeff Zacks, Ph.D.

WORK: Associate professor of psychology in Arts and Sciences at Washington University

HOME: University City

FAMILY: Married to Leslie, who works for a medical publisher; two children: Jonah, 9, and Delia, 5

HOBBIES: Running, biking, fishing, music