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"A large factor of it would actually be that our brains don't store repetitive events very well."

My theory, which is logically consistent with yours, is that as we get older we spend more of our cognitive cycles thinking in terms of abstractions rather than using our senses to process direct experience. This is partly because as we get older we tend to immediately place things we experience into categories and then move onto processing these abstractions rather than continuously observing reality directly and unfiltered. So the other part of the theory would be that when we think in terms of abstractions, time goes by much faster than when we focus on direct sensory experience. It's likely that novelty also plays a role here as a mediating variable, in that we tend to pay more sustained attention to novel phenomena rather than immediately placing them into conceptual buckets and moving onto the next thing.

I also like this theory because it's consistent with how drugs that alter our sensory perceptions and make us focus more on our perceptions also tend to subjectively slow down time. Anyway I have no idea whether this is correct, but IMHO it's a much better theory than the original, which isn't especially logical and doesn't even really make sense.

> we get older we spend more of our cognitive cycles thinking in terms of abstractions rather than using our senses to process direct experience.

This would explain why vacation makes time slow down, yet go fast at the same time. The slow down for the new experiences, environment. The fast - for the lookahead-cache driven feeling of sometimes anxiety/dread of going back to the daily routine.

> as we get older we tend to immediately place things we experience into categories and then move onto processing these abstractions rather than continuously observing reality directly and unfiltered.

Wow, this makes so much sense, and accounts for why (in general) people get less receptive to new ideas as they get older: no categories to place the abstractions in.

You just described my theory exactly. Humans have to learn how to exist in the "zone" of mental abstraction... this is necessary for advanced cognition, but while we're doing it we don't really notice the passage of time.

I can't help but wonder if the hours I spent waiting for the last few minutes of boring class periods to end during my schooling might have actually been great training for "zoning" where the sped up passage of time is actually the goal.

I've often thought the same thing. It has me thinking cautiously about the sociological implication rapidly expending 'senior' demographic, growing life expectancy, and the rapid pace of world changing technologies. Is there a point where senior citizens can't keep up cognitively, despite the medical advances that may keep their bodies younger? And further, is there a point where their dominance as a percentage of society means we need to slow our adoption rate of consumer technologies to account for neurological barrier?

I also think about the people who want their brains crygenetically frozen after they die. Assuming they die old, with this cognitive scaffolding adapted to life today, I can only imagine the impact of 'waking up' into a world 100-300 years in the future, with such a drastically different world. That sounds psychologically crippling to me.

And finally, are there techniques I can take advantage of now, when I'm [comparatively] young, to keep my brain receptitve to new ideas, mental models, and raw sensory input? Meditation? Arts? Travel? Literature? All of the above, and if so, where do I find time for it all, while advancing my career?

> All of the above, and if so, where do I find time for it all, while advancing my career?

As the cliche goes, if you don't find time for it now, you'll pay for it later.

Walking with bare feet and/or walking on uneven ground +1

http://www.ori.org/Media/pressreleases/release01_05_04.html

Art +1

"For Healthy Aging, a Late Act in the Footlights"

http://opinionator.blogs.nytimes.com/2012/08/15/for-healthy-...

While we're on pet hypotheses, what about the fact that the brain simply gets bigger? If neural signals–maxing out at ~100 m/s–took longer to traverse the average distance through the brain, one's perception of time would seem to slow down.

Anecdotally, when I was 8 or so I once sat there for an hour or so memorizing the rate of the clock (so I could later mentally estimate intervals of time without a stopwatch). At the age of 23, I noticed and then calculated that a second in my "internal" clock was about 1.3 seconds. Since then I have used VLC to re-watch movies I saw as a child at ~80% speed. The musical rhythms seemed closer to what I remember.

Obviously this is insufficient support by itself, but I's love to see this phenomenon studied more rigorously.

I think there might be some experimental data in support of the fact that (at least some types of) neurons get slower as we age, though I believe it was for metabolical reasons not due to connection length. I still think you might have a good point there not only due to that cellular slow-down, but also because I would certainly expect an increase in connection density, thus leading to longer computations.

I seem to recall an article from Joel on Software about the same phenomenon from a procedural point of view, where he compares increasingly complex institutional reaction times to the increasing amount of ritual that is being performed before we leave the house (with old people taking the longest time, because based on past experience of all things that went wrong in the past, their checklists before leaving the house become absurdly long over time).

Just an interesting side observation about the VLC speed thing: my personal sense of rhythm has always been so bad that I couldn't tell the difference between 100% speed then and 80% speed now. But an observation I recently made was that I can now comfortably listen to videos at 110% or even 120% their speed without losing content - something I certainly couldn't do at a younger age (in fact, I remember I often had to pause recordings in order to think about stuff that just happened or even just to empty my "language recognition buffer" before I could move on). So while it may well be true that 1 second doesn't last as long for me as it used to, I certainly seem to have become more efficient at processing some types of data.

Wow! This sounds like you could design an experiment for this. It might take at least something like 5 years to see any results. But thats a timeframe many scientists should be willing to pursue.

If you don't want to do those experiments yourself maybe you should eMail some Professors who are interested in this topic.

I think this comment is a slight bit too critical for an OP that's obviously in the genre of playing with ideas. (Most of everything2 seems in this genre.)

> a large factor of it would actually be that our brains don't store repetitive events very well

Depends on what you mean by "very well". Aggressive data compression is usually considered a good way of storing things.

My criticism of the article is so harsh exactly because it does not represent itself as merely an idea, it instead attempts to convey the impression of being a groundbreaking scientific discovery.

> Depends on what you mean by "very well". Aggressive data compression is usually considered a good way of storing things.

We're fundamentally in agreement on this. It is, however, not lossless compression, and that's in part where I would assume the speedup comes from.

> My criticism of the article is so harsh exactly because it does not represent itself as merely an idea....

It's literally titled "Why time appears to speed up with age (idea)".

>>This would also explain why days with unusual content seem to last much much longer than others (at least that's my experience).

I've heard this explained in part because of how our neocortex works. New events tend to require the involvement of more layers of the neocortex than ones that are redundant and routine. This is part of the explanation for the time dilation we experience when surprised by something like a car crash or a thrill seeking adventure. Your mind is fully engaged much the way it was when you were younger and everything was a new experience. As your mind adapts the neocortex handles the events more efficiently; more reflexively. Your mind subconsciously ignores the sensory inputs that don't surprise you.

For this reason, it's often advised that if you want to slow down the apparent passage of time just change your routine. Granted...your neocortex would probably even adapt to this.

Cortical layers tend to be more of a way of dividing a specific low-level task up into sub-functions of information processing. For example, they do different networking/interconnect jobs in different layers and as one would expect different areas of the neocortex have varying layer counts (ranging from 1 to 6).

A more comprehensive computational unit of the cortex is actually the neocortical column which is a "horizontal" patch of neocortex. This is a functional unit that is probably very close to a microprocessor in analogy in that it contains a set of variables, some processing rules, input and output wires, and the capability of executing functions. A whole patch of cortical columns forms a sort of processing center, and interestingly enough, those tend to be specialized for certain kinds of information processing tasks. That's why in an fMRI scan whole areas of the cortex tend to light up together, and it's often the same areas geographically even if you scan a lot of people.

So if we're talking about a theory of localized neocortical involvement, my first impulse would be to check out those specialized areas for (non-)activity - something that led to pretty good empirical results before in related studies - as opposed to using the layers for that hypothesis.

Yes, that's a closer description than what I recall. My understanding is based on a book I read several years ago: http://www.amazon.com/On-Intelligence-Jeff-Hawkins/dp/080507...

I'm also partial to the "perceived time == amount of new experiences" theory. Some years seem much longer than the years that came before them because i had lots of new experiences those years.

Your pet hypothesis and mine are quite similar. Hey there pet hypothesis buddy.

Once you get a good routine down, you figure out the best grocery stores for everything, find the best routes to and from work/school, punch a clock for half your weekday waking hours, days start blending together. The time spent doing things like washing dishes, doing laundry, prepping meals, shopping for consumables, your brain is on autopilot for most of that time once you have done those things 100+ times.

Variety being the spice of life and all, doing new things forces you to actually engage your surroundings and have memorable experiences.