Although modern humans do not have to worry about fleeing from predators, our brains may still contain adaptations that respond to such dramatic changes in the environment.

Scott Huettel, assistant professor of psychology and behavioral science, showed research subjects a random series of squares and circles on a computer screen and asked them to push one button when they saw a circle, and the other button when they saw a square. Meanwhile, researchers analyzed their brain activity using a device called functional MRI.

Huettel said he was particularly interested in the subjects' response when a pattern--such as a short string of circles or squares--was broken. "We looked at how brain function changed specifically to events that violated repeated or alternating patterns," he said.

Huettel and his colleagues found that the prefrontal cortex region in the brain appeared to be activated when a pattern was interrupted.

"When a long pattern was violated, that triggered a larger response in that area.... [It was] strictly graded from largest to no response for the shortest patterns we looked at," he said.

Clinical applications of these findings may not be obvious, but untangling mysteries of the brain's function may answer questions about how our brain evolved to detect danger in our surroundings.

"What this shows is that the human brain really looks for structure in the world," Huettel said. "We are set up to find patterns.... It allows us to extract regularity from the world."

Huettel gave examples of situations like an approaching thunderstorm or predator that may require the brain to spur the body into action. These disturbances change the pattern of regularity perceived by the senses, attracting the brain's attention, Huettel said. "The detection of the patterns becomes very adaptive," he said.

Huettel added that humans may develop superstitions by detecting patterns between unrelated events in much the same way.

For example, people may associate a particular cheer with winning a baseball game. If victory follows the cheer on a number of occasions, the brain may establish this connection as a consistent pattern.

"We may build associations... between some event and a good outcome later. We see these relationships even when there is no common link between them," he said.

Huettel used the fMRI to observe relative levels of brain activity, as determined by the amount of oxygen sent to the prefrontal cortex.

"While a standard MRI image is sensitive to the physical property of a tissue, an fMRI is sensitive to change in blood oxygenation level, which is how much oxygen is carried by hemoglobin in one part of the brain," he said.

Huettel's future research may focus on detailed patterns or examine the pattern-making ability of patients who have suffered brain trauma.

"Some of the next steps are to look at more complicated patterns.... How do people distinguish between things that are important to behavior and those that are less important?" Huettel said.