While the technology does have the potential to enhance your abilities to perform tasks, researchers at Drexel University wanted to determine the real effects of head-mounted displays, so they used functional near-infrared spectroscopy to measure mental workload as subjects navigated their campus.
In an attempt to monitor exactly how these wearables affect the human brain in everyday situations, the Drexel team developed a portable system that employs functional near-infrared spectroscopy, or fNIRS, to measure brain activity.
Current applications for fNIRS are abundant: from training air traffic controllers and drone operators, to studying how students with disabilities learn best, or why different people are more receptive to certain Super Bowl commercials.
"This is a new trend called neuroergonomics. It's the study of the brain at work—cognitive neuroscience plus human factors," said Hasan Ayaz, PhD, associate research professor in the School of Biomedical Engineering, Science and Health Systems and a member of Drexel's CONQUER Collaborative. The phrase was coined by the late Raja Parasuraman, a former professor at George Mason University and study co-author.
Up until this point, most studies with fNIRS took place indoors, but the Drexel biomedical engineers, in collaboration with researchers at George Mason University, brought their portable fNIRS system outdoors to measure the brain activity of participants navigating a college campus.
The researchers compare one group of participants navigating campus with Google Glass to another group using Google Maps on an iPhone. The goal of the study was to measure how hard the brain was working and the users’ perception of environmental elements to see which device was less mentally taxing.
What they found was that overall the Google Glass users had a higher situational awareness and lower mental workload than their peers that were using the iPhone.
However they also discovered that users wearing Google Glass endured the negative effects of “cognitive tunneling," which means that they focused so much more of their attention on the display, that they ignored other aspects of their surroundings.
"What we were able to see were the strengths and weaknesses of both. Now that we know we are able to capture that, we can now improve their design," said Ayaz, the study's principal investigator. "This opens up all new areas of applications. We will be able to analyze how the brain is functioning during all of these natural activities that you cannot replicate in artificial lab settings."
fNIRS measures oxygenation levels in the prefrontal cortex, the part of the brain that is responsible for complex behaviors like decision making, cognitive expression and personality development. The higher the activity in this area of the brain the less experienced the person is, meaning he or she must work harder at an activity. When someone masters a skill, the processing of information moves toward the back regions of the brain.
In the past, researchers had to use secondary tasks to measure the "user-friendliness" of an augmented reality product such as Google Glass. For instance, while a person was navigating with a map application, he or she would be asked to recall a series of sounds played to them through headphones. If his or her response was inaccurate, this implied that the brain had to work harder to pay attention to the primary task at hand.
"We observed greater mental capacity reserves for head-mounted display users during ambulatory navigation based on behavioral and neuro-metabolic evidence. However we also observed evidence that some of the advantages of head-mounted displays are overshadowed by their suboptimal display symbology, which can be overly attention grabbing," said Ryan McKendrick, PhD, the study's lead author and now a cognitive scientist at Northrop Grumman Corporation.
The researchers found that Google Glass users experienced some cognitive tunneling while navigating, so they suggest that future studies need to explore other brain biomarkers induced by this "blindness" to the outside world. According to the research team, by identifying cognitive tunneling biomarkers, engineers could advance display design for navigation, training and other tasks that wearable displays seek to improve.