Imagine a restaurant full of people: plates clinking, music playing, people talking loudly to each other. It’s amazing that someone in that kind of environment can concentrate enough to have a conversation. A new study by researchers at Brown University’s Carney Institute for Brain Sciences provides some of the most detailed insights yet into the brain mechanisms that help people pay attention amid such distraction, as well as what What happens when you can’t concentrate.
In a previous psychology study, researchers established that people can separately control how much they concentrate (enhancing relevant information) and how much they filter (tuning out distractions). The team’s new research, published in Nature Human Behaviorreveals the process by which the brain coordinates these two critical functions.
Lead author and neuroscientist Harrison Ritz compared the process to the way humans coordinate muscle activity to perform complex physical tasks.
“Just as we bring together more than 50 muscles to perform a physical task like using chopsticks, our study found that we can coordinate multiple different forms of attention to perform acts of mental dexterity,” said Ritz, who led the study. study while a Ph.D. Brown student.
The findings provide insight into how people use their powers of attention, as well as what causes attention to fail, said co-author Amitai Shenhav, an associate professor in Brown’s Department of Cognitive, Linguistic and Psychological Sciences.
“These findings may help us understand how we, as humans, can exhibit such tremendous cognitive flexibility: paying attention to what we want, when we want,” Shenhav said. “They can also help us better understand the limitations of that flexibility and how the limitations might manifest in certain attention-related disorders, such as ADHD.”
The focus and filter test
To conduct the study, Ritz administered a cognitive task to participants while measuring their brain activity in an fMRI machine. Participants saw a swirling mass of green and purple dots moving from left to right, like a swarm of fireflies. The tasks, which varied in difficulty, involved distinguishing between the movement and colors of the dots. For example, participants in one exercise were asked to select which color was the majority for fast-moving dots when the ratio of purple to green was almost 50/50.
Ritz and Shenhav then analyzed the participants’ brain activity in response to the tasks.
Ritz, who is now a postdoctoral fellow at the Princeton Neuroscience Institute, explained how the two brain regions work together during these types of tasks.
“You can think of the intraparietal sulcus as having two knobs on a radio dial: one that adjusts the focus and another that adjusts the filtering,” Ritz said. “In our study, the anterior cingulate cortex tracks what happens to the dots. When the anterior cingulate cortex recognizes that, for example, movement is making the task more difficult, it directs the intraparietal sulcus to adjust the filtering knob to reduce sensitivity to the dots. motion.
“In the scenario where the purple and green dots are almost 50/50, you could also direct the intraparietal sulcus to adjust the focus knob to increase color sensitivity. Now the relevant brain regions are less sensitive to motion and more sensitive to the appropriate color, so the participant is better able to make the correct selection.”
Ritz’s description highlights the importance of mental coordination on mental ability, revealing that a frequently expressed idea is a misconception.
“When people talk about the limitations of the mind, they often phrase it in terms of ‘humans just don’t have the mental capacity’ or ‘humans lack computing power,'” Ritz said. “These findings support a different perspective on why we aren’t focused all the time. It’s not that our brains are too simple, but that they are really complicated and it’s coordination that’s difficult.”
Ongoing research projects are based on the findings of these studies. A partnership with physician-scientists at Brown University and Baylor College of Medicine is investigating targeting and filtering strategies in patients with treatment-resistant depression. Researchers in Shenhav’s lab are looking at how motivation attracts attention; a study co-led by Ritz and Brown Ph.D. Student Xiamin Leng examines the impact of financial rewards and penalties on focusing and filtering strategies.
The study was funded by the National Institutes of Health (R01MH124849, S10OD02518), the National Science Foundation (2046111), and by a CV Starr Foundation postdoctoral fellowship.