All she had to do now was think small. Like ping pong small.

For weeks, Studnicki, a graduate student at the University of Florida, served and rallied against dozens of players on a table tennis court. Her opponents sported a science-fiction visage, a cap of electrodes streaming off their heads into a backpack as they played against either Studnicki or a ball-serving machine. That cyborg look was vital to Studnicki's goal: to understand how our brains react to the intense demands of a high-speed sport like table tennis—and what difference a machine opponent makes.

Studnicki and her advisor, Daniel Ferris, discovered that the brains of table tennis players react very differently to human or machine opponents. Faced with the inscrutability of a ball machine, players' brains scrambled themselves in anticipation of the next serve. While with the obvious cues that a human opponent was about to serve, their neurons hummed in unison, seemingly confident of their next move.

The findings, published in the journal eNeuro, have implications for sports training, suggesting that human opponents provide a realism that can't be replaced with machine helpers. And as robots grow more common and sophisticated, understanding our brains' response could help make our artificial companions more naturalistic.

"Robots are getting more ubiquitous. You have companies like Boston Dynamics that are building robots that can interact with humans and other companies that are building socially assistive robots that help the elderly," said Ferris, a professor of biomedical engineering at UF. "Humans interacting with robots is going to be different than when they interact with other humans. Our long term goal is to try to understand how the brain reacts to these differences."