Proposing Physical, Neurological Explanations for Age-Related Differences in the Perception of the Passage of Time
Why does the perception of the passage of time change with age? Having glanced through the short paper referenced in these publicity materials, it has the look of another of the many airy theories on the operation of the mind that must wait around for however long it takes for neuroscience to advance to the point of being able to say anything sensible about how perceived experience relates to physical structure and cellular biology. Still, one has to start somewhere. Final answers and understanding must be preceded by theories that prompt lines of investigation. That theorizing will start out entirely unsupported, and only incrementally become better and more scientific. We shouldn't be holding our collective breath waiting on those final answers, of course. They are quite the long way away.
A researcher has suggested that the perception that days last longer in childhood can be blamed on the ever-slowing speed at which images are obtained and processed by the human brain as the body ages. This phenomenon is attributed to physical changes in the aging human body. As tangled webs of nerves and neurons mature, they grow in size and complexity, leading to longer paths for signals to traverse. As those paths then begin to age, they also degrade, giving more resistance to the flow of electrical signals. These phenomena cause the rate at which new mental images are acquired and processed to decrease with age. This is evidenced by how often the eyes of infants move compared to adults - because infants process images faster than adults, their eyes move more often, acquiring and integrating more information.
The end result is that, because older people are viewing fewer new images in the same amount of actual time, it seems to them as though time is passing more quickly. "The human mind senses time changing when the perceived images change. The present is different from the past because the mental viewing has changed, not because somebody's clock rings. Days seemed to last longer in your youth because the young mind receives more images during one day than the same mind in old age."
Link: https://pratt.duke.edu/about/news/its-spring-already-physics-explains-why-time-flies-we-age