Picture a bustling restaurant: the clinking of dishes, the background music, the cacophony of voices all blending together. It’s amazing how anyone can focus enough to hold a conversation in such a chaotic environment. A recent study conducted by researchers at Brown University’s Carney Institute for Brain Science offers a deeper understanding of the brain mechanisms that allow people to pay attention amidst distractions, as well as what happens when they struggle to focus.
In a previous psychology study, the researchers demonstrated that individuals have the ability to independently control their focus (enhancing relevant information) and their filtering (tuning out distractions). Their latest research, published in Nature Human Behaviour, delves into how the brain coordinates these crucial functions.
Lead author and neuroscientist Harrison Ritz compared this coordination process to how we use multiple muscles to perform complex physical tasks.
“Just like we engage over 50 muscles to complete a physical action like using chopsticks, our research shows that we can coordinate various forms of attention to execute mental tasks,” explained Ritz, who conducted the study during his Ph.D. studies at Brown.
The findings shed light on how individuals utilize their attention capabilities and what factors contribute to attention lapses, according to co-author Amitai Shenhav, an associate professor in Brown’s Department of Cognitive, Linguistic and Psychological Sciences.
“These insights can help us comprehend the remarkable cognitive adaptability of humans – our ability to focus on what we choose, when we choose to do so,” Shenhav noted. “They can also aid in understanding the constraints on this adaptability and how these limitations might manifest in attention-related conditions such as ADHD.”
The Focus-and-Filter Test
To carry out the study, Ritz assigned a cognitive task to participants while monitoring their brain activity using an fMRI machine. Participants observed a swirling pattern of green and purple dots moving horizontally, resembling a swarm of fireflies. The tasks varied in complexity and required participants to differentiate between the dots’ movements and colors. For example, in one exercise, participants had to identify the dominant color among the rapidly moving dots when the ratio of purple to green was almost equal.
Ritz and Shenhav then scrutinized the participants’ brain activity in response to the tasks.
Ritz, now a postdoctoral fellow at the Princeton Neuroscience Institute, elucidated how two brain regions collaborate during these tasks.
“Think of the intraparietal sulcus as having two controls – one for focus and one for filtering,” Ritz elaborated. “In our study, the anterior cingulate cortex monitors the dots. When it detects that, for instance, motion is complicating the task, it instructs the intraparietal sulcus to adjust the filtering control to reduce sensitivity to motion.
“In a scenario where the purple and green dots are nearly equal, it may also direct the intraparietal sulcus to adjust the focus control to enhance sensitivity to color. Consequently, the relevant brain regions become less reactive to motion and more responsive to the correct color, improving the participants’ ability to make accurate selections.”
Ritz’s explanation underscores the significance of mental coordination over mental capacity, debunking a common misconception.
“When people discuss the limitations of the mind, they often attribute it to ‘humans lacking mental capacity’ or ‘humans lacking computational power,'” Ritz pointed out. “These findings advocate for a different viewpoint on why we aren’t always focused. It’s not due to our brains being too simplistic, but rather due to the complexity of our brains and the challenge of coordination.”
Further research initiatives are expanding on these study findings. Collaborating with physician-scientists at Brown University and Baylor College of Medicine, researchers are exploring focus-and-filter strategies in patients with treatment-resistant depression. Meanwhile, Shenhav’s lab is investigating how motivation influences attention; a study led by Ritz and Brown Ph.D. student Xiamin Leng is examining the effects of financial rewards and penalties on focus-and-filter strategies.
The study received funding from the National Institutes of Health (R01MH124849, S10OD02518), the National Science Foundation (2046111), and a postdoctoral fellowship from the C.V. Starr Foundation.
