What our brain’s electrical signals reveal about language, meaning and memory

At one busy exhibit at the 2024 Beckman Institute Open House, visitors donned headbands with sensors and focused on foam balls hovering above small fans. It seemed like the visitors simply watched the balls move up and down, but their headbands actually detected their brains’ electrical signals, letting them control the balls’ movements with their minds.

This exhibit, voted the best interactive exhibit at the open house, was a collaboration between the Cognition and Brain Lab, or CAB Lab, and the Alcohol Research Lab at the University of Illinois Urbana-Champaign.

“The exhibit was trying to highlight, for the public, the cool factor that we can put sensors on people’s heads and actually pick up something about what the brain’s doing, with a high degree of cognitive and temporal resolution,” said Kara Federmeier, a professor of psychology at the Illinois and director of the CAB Lab.

The CAB Lab measures the brain’s electrical signals to explore how the brain links sensory information to meaning and transforms it into memory.

“Everything we do depends on what happens when we see a word and activate stuff,” Federmeier said. “What do we activate? How quickly do we activate it? The answer to all of these questions determines how well we comprehend our world and each other.”

Like the toy in the open house exhibit, electrophysiological methods use sensors to pick up electrical activity in the brain. These electrical signals can be linked to certain events, like reading a word or looking at a picture, to help understand how the brain processes information. Much of the CAB Lab’s research uses a specific electrical response related to meaning comprehension called the N400.

Some of this research looks at how the two hemispheres of the brain connect perception to memory differently. Both halves have similar anatomy, but their networks are not identical. Additionally, the connection between the hemispheres is relatively small, so information can’t constantly be shared between them. As a result, the hemispheres process information independently and in distinct ways.

The CAB Lab found that with language, the left hemisphere prioritizes expectations. For example, in a conversation, this hemisphere uses context clues to predict what words are about to be spoken in a sentence. The right hemisphere is more in-the-moment, testing whether words fit the situation as they come up. It’s important that the brain can simultaneously work both ways.

The lab has found similar differences between how younger and older adults comprehend meaning and language. While adults of all ages might be equally as able to perform a language-related task, the brain works differently in order to reach the same result. Like the left hemisphere, the brains of younger adults are more likely to make predictions about future words and information.

Research on aging highlights the flexibility that exists in the brain’s systems. It also may help to identify markers of language disorders and pathological aging to help with treatment.

Like the open house exhibit, Federmeier believes that cognitive science is inherently collaborative. In the past, members of her lab have worked with the Attention and Perception Lab, looking at how people understand pictures and combining the labs’ expertise in fMRI and EEG.

The lab has also worked with the Alcohol Research Lab, which uses electrophysiological tools to understand alcohol's impact on the brain and identify risk factors for alcohol abuse.

Because electrophysiological methods are relatively inexpensive and portable, they can help address a wide range of questions. Students from various academic areas have done projects in the CAB Lab to study how people choose political candidates, and whether brain signals can be used to predict whether someone will experience virtual reality sickness.

“Interdisciplinarity is both really, really fun and also really critical,” Federmeier said. “One of my favorite aspects of being a faculty [member] at the Beckman Institute is how I almost always have someone in the lab, whose main line of work is different from my own, using EEG to ask all kinds of different questions.”