Better together: coupling up to watch TV and talk synchronizes brain waves
Scientists are a step closer to finding out just why watching TV together and talking is such a popular pastime. Watching the same movie stimulates similar neural activity across brains: a phenomenon referred to as inter-subject correlation. Subjects sitting in the same room and talking over the content have been shown to increase various other measures of brain synchrony.
Now it turns out that we don’t even need to be discussing what’s on the screen to get more in tune with each other during the next show.
Lead author Dr. Sara De Felice, Professor Antonia Hamilton, and other colleagues at University College London used functional near-infrared spectroscopy (fNIRS) to measure brain activity in 27 pairs of adults as they each watched two different episodes of the short BBC children’s cartoon Dipdap. In between the episodes, the subjects talked over trivial facts unrelated to the show, such as exotic animals and musical instruments. The researchers then compared the data on brain activity recorded during each episode to see if the non-relevant chatter had affected mental synchrony.
Their results, published in Oxford Open Neuroscience, showed increased brain synchrony over the right dorso-lateral pre-frontal cortex (DLPFC) and right superior parietal lobe (SPL) in familiar pairs (housemates, friends, or partners) watching the cartoon together compared to pseudo pairs who had not met, and who watched the short film alone. These results are in line with previous studies into these brain regions which indicate that the DLPFC is associated with functions like working memory, abstract reasoning, and cognitive flexibility while the SPL receives significant visual input, and is also associated with reasoning and memory, as well as attention.
The study also found that co-watching after a conversation was associated with greater brain synchrony over the right temporoparietal junction (TPJ)–an area of the brain famous for allowing other perspectives (theory of mind)–compared to co-watching before a conversation. This effect was significantly higher in familiar pairs engaging in conversation with each other than in pseudo pairs who talked to someone else.
“Two things are surprising and novel here,” says Dr. De Felice (now at the University of Cambridge). “First, having a chat resulted in brains also synchronising afterwards. Second, the chat didn’t have to be related to the movie to see this effect.”
The scientists selected fNIRS for this research as it uses light to map blood flow in response to neural activity at sites across the head, allowing the study of natural face-to-face interactions because subjects aren’t physically confined in a noisy fMRI machine.
“fNIRS is non-invasive and robust to movement, allowing the measurement of brain activity from people as they act and interact normally,” says Dr. De Felice. On the downside, its lag time of around five seconds makes it much less spatially and temporally accurate than other techniques.
The researchers found no significant differences in the other five brain regions selected for measurement.
“Brain synchrony was observed in three areas (the DLPFC, SPL, and TPJ) which play a key role in our ability to interact with others, understand intentions and emotions, and interpret other people’s perspectives,” explains Dr. De Felice. “It makes sense that we observe synchrony over these areas during co-watching of the BBC Dipdap cartoon, where the watcher is encouraged to follow and predict what the puppet will face next.”
She suggests the findings, along with those from numerous other studies, could indicate that brain synchrony extends to and from further behaviours: “This might explain why people who spend considerable time together often find themselves in greater agreement with each other than with those they’ve never met. Through such interactions, individuals can develop a shared reality, both physically and mentally.”
The next challenge is to better explore the causal relationship between synchrony and social interaction, examining if altering this synchrony using brain stimulation would alter the parameters of interaction, she says.
Featured image by Sarandy Westfall via Unsplash.
