Scientists may be closer to understanding why time seems to pass more quickly as we age — and brain scans of people watching an old Alfred Hitchcock show helped them address this enduring question.

In a study published Sept. 30 in the journal Communications Biology, scientists pulled data from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN), a long-term brain-aging research project. In total, 577 people had previously watched an excerpt from the old television series "Alfred Hitchcock Presents" — specifically, eight minutes of an episode called "Bang! You're Dead." As the study participants watched the clip, functional MRI (fMRI) scans were recorded; these scans would provide a measure of how the participants' brain activity changed over time.

This particular clip was chosen because previous research showed that, compared with other video clips, it elicits the most synchronous patterns of brain activity in a wide variety of viewers. That makes it ideal for studying how the brain divides and tracks unfolding events.

At the time the brain scans were taken, the participants were between 18 and 88 years old. The researchers got access to these existing fMRI recordings and used the so-called Greedy State Boundary Search (GSBS) to analyze them.

As the name suggests, this computer algorithm detects transitions between stable patterns of brain activity. It does so "greedily" — that is, it identifies these shifts moment by moment, without taking into account the overall structure of the narrative on a longer time scale.

During the eight-minute clip, the brains of older participants shifted to new activity states less frequently, and those brain states lasted longer for them than they did for younger participants. This pattern was consistent across the full age range of 18 to 88 years.

"This suggests that longer [and, therefore, fewer] neural states within the same period may contribute to older adults experiencing time as passing more quickly," the researchers wrote in their report. This aligns with an idea of time that dates back to Aristotle: The more notable events occur in a given time period, the longer it subjectively seems. The new results raise the possibility that if older adults' brains are logging fewer "events" in a given time frame, maybe that's why time seems to fly by.