Graduate student Anna Katikhina, left, and research assistant Hannah Hart inject electrogel into the electrodes on a cap for volunteer Travis Koziol to ensure proper brainwave readings during a study on reactions to language, words and sentence structure.

If someone says it’s been a “rough” day, most people wouldn’t think of a day with a sandpaper texture, but our brains might just process it that way.

Vicky Lai, an assistant professor of psychology and cognitive science at the University of Arizona, is working to understand how the brain processes figurative language. She recently published a paper testing how, and how quickly, different parts of the brain respond when a person uses a metaphor.

This could help researchers not just understand the brain and language better, as many of those processes are not fully understood, but could also be used to develop more efficient ways of learning. Humans, research has shown, use a metaphor about every 20 words.

Lai, director of the Cognitive Neuroscience of Language Laboratory, has been studying the way the brain processes metaphors since her time as an undergraduate in Taiwan. There, she worked on a linguistic project that looked at how people used metaphors to talk about big life events and how the metaphors could signal changing views.

“We got together and we discussed all kinds of metaphors every week,” Lai said. “If you ever sit down and discuss the details of language and how concepts relate to one another, that certainly helps in formulating that interest.”

While working toward her Ph.D., she started to measure brain activity to understand how the brain processes metaphors more fully. There, she used a functional MRI, which detects blood flow in the brain, to see which regions of the brain were responding and discovered that even familiar metaphors that would seem to be easy to understand showed different brain profiles than literal language.

At the same time, collaborator professor Rutvik Desai at the University of South Carolina found that metaphors related to action, like to “grasp” an idea, activated the motor-related areas, or cortices, of the brain. Similar findings in other labs at Emory University and Princeton University also found that for metaphors related to the senses, like a “rough” day or a “sweet” girl, the sensory cortices of the brain were also active.

“What we consider to be abstract is also grounded in our sensory motor physical body experiences,” Desai said.

In the most recent experiment, Lai and Desai went a step further and focused on the timing of how the brain processes metaphoric language to try to discern if the sensory cortices of the brain are activated only after the brain processes the word, or if the sensory cortices are actually a vital part of the process.

“It’s not clear which comes first,” Lai said.

Desai and Lai designed the study and wrote the paper, while the data collection was done by Lai. An electroencephalogram, or EEG scan, was used to measure electrical activity in participants’ brains. The participants wore electrodes on their heads and then read a series of sentences on a computer screen while their brainwaves were recorded.

An example of the sentences are, “The church bent the rules” where the verb “bent” is a metaphor, then, “The bodyguard bent the rod”, where “bent” is used literally, and finally a baseline verb that means the same as “bent” but is not a metaphor, like “The church altered the rules.”

The EEG then records how the brain reacts. Desai said an EEG was needed to get a close look at exactly when and how the brain was reacting, because while a functional MRI might show regions of the brain being activated, it doesn’t show the timing.

“We know that in an EEG there is a different signal for concrete concepts versus abstract concepts, so by using EEG we can look at not only the time codes but we can see whether that brain signal is more like a concrete item or more like an abstract item,” Desai said.

Lai looked specifically at the brain’s reaction to the verb, and found that the brain activated at about the same time — almost immediately — when it came to the reading of the metaphoric verb and the literal verb. That response differed when “bent” was replaced with “altered.” This suggests that the motor-related cortices of the brain were necessary for understanding metaphors.

“We’re not saying that’s the absolute evidence, but we’re saying we’re one step closer, because of the rapid activation,” Lai said.

The research is laying the groundwork in Lai’s lab for future studies into the role of metaphors in cognition and emotion.

The research could have a more clinical application later, Lai said, to help people learn more efficiently, to understand and apply the role figurative language has in emotional health, or for people with autism spectrum disorder, who often have trouble understanding figurative speech.