Watching TikTok and Instagram shorts deactivates the brain's cognitive control network: study

A study from Zhejiang University, published in NeuroImage in January 2026, finds that finishing a short video a viewer enjoys temporarily quiets the brain regions that normally help people stay focused and weigh longer-term goals.

How the experiment was run

The team recruited 66 volunteers and excluded 10 for head motion or poor spectroscopy data, leaving 56 participants (37 men and 19 women, average age 23.3), all short-video users. Before scanning, a MEGA-PRESS sequence measured resting-state glutamate and GABA in each participant's dorsal anterior cingulate cortex (dACC), with a matched voxel in the visual cortex as a control. Inside the scanner, participants watched two six-minute blocks of clips from a library of 160 videos.

What showed up in the scans

Average clip length was 23.7 seconds; participants could skip at any time. Videos were classed as liked (watched to the end) or disliked (skipped before halfway); on average, participants watched about 19 liked and 36 disliked clips per session. The study had been preregistered in September 2024.

Both the dACC and the dorsolateral prefrontal cortex (dlPFC) deactivated significantly below baseline during liked videos (t = -6.30 and -12.20 respectively). During disliked clips the pattern diverged: dACC activity stayed close to baseline, while dlPFC remained suppressed, though less severely (t = -3.73). The visual cortex activated in both conditions with no difference, indicating an effect specific to cognitive control regions rather than a general effect of watching video. Higher resting-state dACC glutamate predicted less suppression there, while GABA showed no significant relationship with either region. Connectivity between dACC and dlPFC rose above baseline in both conditions, more strongly during liked videos.

Interpretation and limitations

The researchers caution against reading the deactivation as impaired cognitive function: as they put it, "this deactivation should not be interpreted as a failure of cognitive control capacity." They argue it reflects an adaptive shift toward low-effort, automatic processing, noting that participants skipped disliked clips on roughly 57 percent of trials, which points to sustained evaluation rather than disengagement. Limits the authors list: neurotransmitters were measured in the dACC only; no causal test of amygdala involvement; no validated scale for problematic use; liking inferred solely from completion; a young, healthy, mostly male sample; and a correlational design. The paper is Hong, T., Su, C., Zhou, H., Geng, F., & Hu, Y. (2026), NeuroImage, 327, 121722.