When it was first released three years ago, Google Glass was deemed a breakthrough in wearable technology. Though Google stopped producing the original Google Glass prototype last year, smart eyewear isn't going away anytime soon--Google, Sony, and Samsung have all filed patents for smart contact lenses.

Now, a recent study published in Frontiers in Human Neuroscience suggests these kinds of devices impact the brain more than you might think. Smart eyewear may help you process information more quickly--but it also might make you less perceptive of what's going on around you.

Twenty people, divided into two groups of 10, participated in the study. The researchers, from George Mason University and Drexel University, gave one group a hand-held navigational display (Google Maps), and the other an augmented reality wearable display (Google Glass). Both devices displayed maps of four different routes that participants were instructed to walk along.

Along the way, researchers used what's called a Functional Near-Infared (FNIR) sensor to measure the oxygenation levels in the prefrontal cortex, which is the part of the brain responsible for decision making, among other behaviors. The oxygen levels observed in individuals using Google Glass indicated that their cognitive workload was lower--that is, that it was less mentally taxing for participants to use Google Glass versus Google Maps. But, the individuals who used Google Glass appeared to be more prone to ignore other aspects of their surroundings and focus on the display, in a phenomenon known as "cognitive tunneling."

While being unaware of your surroundings might not be harmful on a leisurely walk, it could be a bigger problem in some professional applications. Researchers wrote that cognitive tunneling is "often implicated in aviation studies where a failure to perceive and act on an unexpected event reduces performance."

To be sure, the sample size was small, so it's important to take these results with a grain of salt. Much work remains to be done in this area. But what's particularly noteworthy about this study is how researchers were able to design a portable FNIR in the shape of a headband. In the past, FNIR sensors had to stay in a lab, and be hooked up to a computer in order for researchers to record the results. Now they can transfer the information captured by the FNIR sensor wirelessly, and the researchers were able to design a control panel that fit inside the headband.

According to  Hasan Ayaz, an associate research professor in the School of Biomedical Engineering, Science and Health Systems and a member of Drexel's CONQUER Collaborative, the majority of FNIR sensors still aren't portable. He hopes that with the sensor his team has developed, they'll be able to monitor more frequently how participants react to wearables and other smart devices in a more natural, everyday setting. It's part of a trend that Ayaz's calls neuroergonomics--the study of the brain at work.

"Because we can now actually take the equipment out of the lab, we can do more of an investigation into how the brain acts in the real world," Ayaz says.