As the old saying goes, many people see the eyes as windows to the soul. One young scholar in psychology, however, views them as windows to the brain.
Dr. Brett Bahle’s research examines how we focus our attention on objects within the visual field. The eyes are one of the primary ways we gather sensory information about the world – we move them about three times per second on average – so understanding the factors behind eye movements could provide more knowledge on sensory processing and attention.
“Some of the most important tasks that can be life or death in our society are actually visual search tasks,” says Bahle. “You can think of radiologists looking for dangerous things like cancer in medical images – that’s a visual search task. If we can better understand how people natively conduct visual search tasks and their visual search behavior in general, then we can use that information to better train them in catching mistakes.”
His dissertation investigates the role two key factors play in influencing eye movements: visual features of objects and their likely spatial locations. Part of his research involved tracking participants’ eye movements during experiments as they conducted visual searches for specific objects. These searches provided further evidence that both factors serve as sources of information in guiding visual attention.
Bahle found that participants were inclined to look for objects where they would normally expect them to be – in their likely spatial locations. However, his research suggests that people are more inclined to guide their searches based on the visual features of objects. Regardless of location, participants were more likely to look at objects that had similar visual characteristics to the object of interest. In other words, someone searching for the Iowa tigerhawk would be likely to look at other yellow things as well.
Bahle was also curious about whether people can look for multiple items at once. He developed another set of experiments in which participants were instructed to search for two colors simultaneously among a wider visual field of colors. When both target colors were present in the display, participants were able to locate both target colors more quickly on average than when just one color was present.
This research suggests that people are able to successfully look for multiple items at once, even when their visual features are very different. Bahle’s dissertation provides additional insight on visual working memory and how multiple items from it can guide attention at the same time. He sees this research as a way of learning more about how the brain itself behaves.
“Visual search is a really fundamental human behavior that is important to understand in its own right,” says Bahle. “The eyes are one of the brain’s primary ways of interpreting the world. By better understanding the behavior of the eyes, we will better understand the behavior of the brain, which is ultimately what I want to understand.”
While Bahle’s scientific curiosity was a key part of his motivation throughout his research, he faced his own setbacks throughout his program. He had moments of self-doubt and criticism like many other graduate students at times. However, he credits the support of his peers and program faculty in helping him stay upbeat and focused on his research.
“I had a lot of honest and encouraging people around me at Iowa, such as my advisor, Andrew Hollingworth, along with Toby Mordkoff, Cathleen Moore, and Shaun Vecera – to name a few of the other faculty members,” says Bahle. “They would all give me honest critiques and valuable information for improving my work in an encouraging way. They would tell me when I had good ideas, and when I didn’t have a great idea to start with, they would help me mold it into something better.”
Bahle reflects on the support his faculty and mentors offered him at Iowa as he continues his research beyond the program. In his current position as a postdoctoral researcher at University of California-Davis, he is conducting similar research with more direct measurements like electroencephalography (EEG) recordings and other brain imaging techniques.
His work at Iowa was duly recognized with the Graduate College’s 2020 D.C. Spriestersbach Dissertation Prize in the Social Sciences. Bahle sees his current research as an extension of his work at Iowa and appreciates the new commendation for his dissertation.
“I was extremely honored to win the Spriestersbach Prize,” says Bahle. “There is a lot of great work being done in the Psychology Department at Iowa, so to even be nominated by the department was humbling. I know a lot of the past winners did excellent work and even went on to win the national dissertation award, so I’m really honored to be acknowledged alongside them.”