Short-video viewing temporarily shuts down cognitive control networks, study finds

Watching preferred short videos may temporarily quiet brain regions involved in self-control and monitoring, and this effect could be linked to levels of the brain chemical glutamate. This research was published in NeuroImage.

Short-video platforms are built around quick, engaging clips that users can continue or skip within seconds. These platforms can be entertaining and harmless for many people, but researchers have become increasingly interested in why some users find them difficult to stop using. One possible explanation is that immersive, pleasurable viewing may reduce the need for active monitoring and self-control.

The new study focused on two brain regions: the dorsal anterior cingulate cortex and the dorsolateral prefrontal cortex. The dorsal anterior cingulate cortex helps detect conflict, monitor behavior, and decide when more mental effort is needed. The dorsolateral prefrontal cortex is involved in applying control, such as staying focused or resisting distraction. Together, these areas help people regulate behavior in situations where attention and self-control are required.

The researchers also examined two brain chemicals. Glutamate is the brain’s main excitatory neurotransmitter, meaning it helps increase neural activity. Gamma-aminobutyric acid, or GABA, is the brain’s main inhibitory neurotransmitter, meaning it helps reduce or regulate neural activity. The team wanted to know whether these chemicals, measured at rest, could help explain why people differ in how strongly their cognitive control network responds during short-video viewing.

Led by Tiantian Hong of Zhejiang University in China, the researchers recruited 66 young adults. After excluding participants because of excessive head movement or poor-quality brain chemistry scans, the final sample included 56 people with an average age of about 23 years. The sample included 19 females.

Participants first underwent proton magnetic resonance spectroscopy, a brain imaging technique used to estimate glutamate and GABA concentrations in the dorsal anterior cingulate cortex. They then completed a short-video viewing task during functional magnetic resonance imaging, which measures changes in brain activity. Participants watched two six-minute blocks of videos and could press a button to skip to the next video whenever they wanted. Videos watched to the end were treated as “liked,” while videos skipped before halfway were treated as “disliked.”

The main finding was that liked videos were associated with significant deactivation in both cognitive control regions. In other words, when participants watched videos that they allowed to continue, activity in the dorsal anterior cingulate cortex and dorsolateral prefrontal cortex fell below baseline.

Disliked videos demonstrated a different pattern. During these videos, activity in the dorsal anterior cingulate cortex did not significantly differ from baseline, while the dorsolateral prefrontal cortex was still suppressed. The visual cortex, which processes visual information, was active during both liked and disliked videos, suggesting the results were not simply because participants were looking at a screen.

Hong and colleagues also found that people with higher resting glutamate in the dorsal anterior cingulate cortex showed less suppression of both cognitive control regions during video viewing. GABA was not significantly associated with activity in these regions. The authors concluded that immersive viewing of preferred short videos deactivates the cognitive control network, and individual differences in this deactivation are linked to glutamate metabolism.

Interestingly, connectivity between the dorsal anterior cingulate cortex and dorsolateral prefrontal cortex increased during short-video viewing, especially for liked videos. The authors caution that this does not necessarily mean stronger self-control. Instead, they suggest the two regions may be jointly downregulated during preferred viewing, producing a more coordinated pattern of reduced activity.

Some limitations are to be noted. For example, the study did not assess short-video addiction or compulsive use in detail, and “liked” videos were defined by whether participants kept watching rather than by explicit post-viewing ratings. In addition, the study only recruited young adults with a predominantly male makeup, which limits the generalizability of the findings.

The study, “Brain activity inhibition during Short Video Viewing: neurochemical insights,” was authored by Tiantian Hong, Conghui Su, Hui Zhou, Fengji Geng, and Yuzheng Hu.