Ask most adults in their forties or fifties and they will tell you the same thing: the years are moving faster than they used to. A decade that once felt endless now seems to compress into a handful of summers. This is not nostalgia or complaint. It is a consistent, cross-cultural phenomenon that people report with enough regularity that researchers have been trying to explain it for decades. A study published in September 2025 may have found its clearest neural explanation yet.

The Hitchcock experiment

The study, by Lugtmeijer and colleagues at the University of Cambridge, drew on data from the Cambridge Centre for Ageing and Neuroscience project, a long-running effort to track how the brain changes across the adult lifespan. The team recruited 557 people aged 18 to 88 and scanned their brains while they watched a segment of an old Alfred Hitchcock television program.

The choice of stimulus was deliberate. Hitchcock’s direction is rich in moment-to-moment shifts: changes in tension, attention, camera angle, and emotional register. The researchers used a technique called neural state segmentation to identify how the brain divided this continuous stream of experience into discrete chunks, what they called neural “events.” Each time the brain registered a meaningful shift in what was happening, it created a new event boundary. The more boundaries, the more the brain had carved the experience into distinct, memorable episodes.

Older brains carve fewer chapters

What the scans showed was striking. Older participants produced significantly fewer and longer neural events while watching the same material. Their brains were parsing the same stretch of time into fewer distinct segments, particularly in the visual cortex and in a prefrontal region associated with episodic memory encoding. The “chapters” were longer and blurrier.

The researchers tied this to a well-documented process called neural dedifferentiation, in which brain regions become gradually less specialized with age. A younger visual cortex responds sharply to shifts in visual content. An older one tends to respond more broadly, with less precision. Fewer sharp responses mean fewer event boundaries, which means fewer distinct memories laid down per unit of clock time.

“When we look back on a period of time, we are essentially counting the memories we have from it. If fewer distinct events were encoded, the period feels shorter in retrospect, even if the clock said otherwise.”

Why childhood summers felt so long

This finding offers a neural account of something people have been noticing informally for as long as there has been human reflection on time. Childhood is full of new experiences, unfamiliar environments, first encounters with things not yet understood. A young brain encountering novelty creates sharp, numerous event boundaries. Every day contains many distinct memories. Looking back, the period feels long, almost endless.

Adult life, particularly for people settled into routine, contains far fewer genuinely novel experiences. A familiar commute, a meeting very like last week’s meeting, a dinner much like last Tuesday’s dinner: these events produce fewer new boundaries, fewer distinct memories, and in retrospect feel like they passed in a blur.

The neurological and the experiential accounts are consistent with each other. The 2025 study adds a mechanism to a phenomenon that previously had only anecdote.

Can anything slow the clock?

The research group was careful not to overstate the implications, but the logic of their findings does point in a practical direction. If time feels faster when the brain encodes fewer distinct events, then anything that increases novelty and attention should, in principle, make time feel more expansive. Travel, new skills, unfamiliar social environments, and any experience that forces genuine attention rather than automatic processing all create more event boundaries. The effect is stronger during the experience than after it: a slow, boring afternoon feels long in the moment but short in memory. A rich, novel day feels fast in the moment but long in memory.

The broader implication is that time perception is not a passive recording but an active construction. The brain does not register every second equally. It creates a narrative from events, and the richness of that narrative, more than the number of seconds it spans, is what determines how long a period of life seems to have been.

A question of attention

Neural dedifferentiation is real and it does increase with age, but it is not entirely fixed. Cognitive engagement, physical exercise, and continued learning have all been associated with slower rates of dedifferentiation. Whether any of these interventions measurably changes time perception is not yet known. What the Lugtmeijer study establishes is where to look: at the sharpness of neural event boundaries, and at the question of how many distinct moments a brain can be persuaded to notice in the course of a day.

Sources

  • Lugtmeijer, S., et al. (2025). Age-related differences in neural event segmentation and temporal memory. Communications Biology. Cambridge Centre for Ageing and Neuroscience (Cam-CAN).
  • Zacks, J.M., et al. (2007). Event perception: A mind-brain perspective. Psychological Bulletin.
  • Haber, S., et al. (2023). Neural dedifferentiation and cognitive aging. Neuroscience & Biobehavioral Reviews.