A hare and a tortoise walk into a bar

September 23, 2013 6:28 PM

How animals perceive time. 'FLIES live shorter lives than elephants. Of that there is no doubt. But from a fly’s point of view, does its life actually seem that much shorter? This, in essence, was the question asked by Kevin Healy of Trinity College, Dublin, in a paper just published in Animal Behaviour. His answer is, possibly not.'

'Subjective experience of time is just that—subjective. Even individual people, who can compare notes by talking to one another, cannot know for certain that their own experience coincides with that of others. But an objective measure which probably correlates with subjective experience does exist. It is called the critical flicker-fusion frequency, or CFF, and it is the lowest frequency at which a flickering light appears to be a constant source of illumination. It measures, in other words, how fast an animal’s eyes can refresh an image and thus process information.'

posted by VikingSword (27 comments total)

"For people, the average CFF is 60 hertz (ie, 60 times a second). This is why the refresh-rate on a television screen is usually set at that value."

I'm very skeptical of these numbers, having studied the visual system a bit. Admittedly I was only an undergrad but even so I learned enough to doubt such hard and fast approximations. Humans can visual stimuli at a higher rate, and the system doesn't use vertical sync like a monitor or the like. The reason TVs are set at that rate is also more complicated than this.

The research sounds fascinating, and I have asked this question myself, but this seems like rather a crudely constructed metric.
posted by BlackLeotardFront at 6:39 PM on September 23, 2013 [4 favorites]

Interesting idea. Do flies even have a subjective experience of anything, though? I would think (possibly wrongly) that you need to have some form of consciousness for that, and flies seem pretty likely to be below the cutoff point, although who knows really...
posted by Jon Mitchell at 6:41 PM on September 23, 2013

To put this idea to practical use, if you squash a spider, does it have time to feel he's being crushed? Does he feel pain for a moment - or for an endless moment?
posted by hat_eater at 6:44 PM on September 23, 2013 [1 favorite]

That assumes consciousness has a cutoff point rather than being a continuum. A veritable rabbit-hole this whole enterprise...
posted by meinvt at 6:44 PM on September 23, 2013

Scientist times flies and concludes fly time doesn't fly.
posted by weapons-grade pandemonium at 6:45 PM on September 23, 2013 [24 favorites]

I'm very skeptical of these numbers, having studied the visual system a bit.

Well there's a range at work, but there are a lot of different technologies which corroborate a frequency in this general range. Most people don't perceive theatre film flicker at 24 FPS, even when the screen is full dark half the time, but increasing the frame as far as 72 FPS has proven to change peoples' unconscious perception of the film. We perceive lights flickering at 50-60 Hz as continuous.

However I would agree that there is more going on, particularly in humans where the visual cortex is a relatively shallow part of the entire pool. The thing is, that shallowness of vision with respect to the rest only makes the OP argument firmer, because if V1-V5 is just 10% of the depth necessary for a conscious reaction for humans as opposed to 20% or 30% of the depth for an animal with a simpler cognitive system, then they are really seeing the world crawl by compared to what we perceive.
posted by localroger at 6:52 PM on September 23, 2013 [2 favorites]

Most people don't perceive theatre film flicker at 24 FPS,

Slight pedantry: everyone perceives theatre film flicker at 24 FPS, which is why the projector lamp window runs at 48FPS, (ie it's kind as if it's projecting at 48FPS but showing each frame twice). That classic old-timey movie flicker is what happens at lower speeds.
posted by anonymisc at 7:02 PM on September 23, 2013 [2 favorites]

From a fly's point of view, he just repeatedly tried to fly through the same glass window, over and over and over, for five years.

In the fly's defense, I've spent that long in my own ruts too.
posted by anonymisc at 7:05 PM on September 23, 2013 [3 favorites]

BlackLeotardFront: ""For people, the average CFF is 60 hertz (ie, 60 times a second). This is why the refresh-rate on a television screen is usually set at that value.""

This is incorrect. It's set at that rate in the US because that's the mains frequency, and it's 50 in Europe because that's the mains frequency there. Then they fudged it a bit to get color information in, and so on, but the main reason it is what it is isn't because of the human visual system. If I were to guess, the limit is probably somewhere in the 40-50 Hz range for most people.
posted by Joakim Ziegler at 7:23 PM on September 23, 2013 [4 favorites]

Obviously Europeans are 16.6% more relaxed than Americans and perceive time more slowly, hence why European electricity runs slower. This is also why I sometimes feel disorientated as a European living in America.
posted by kersplunk at 7:42 PM on September 23, 2013 [4 favorites]

I've always thought this about flies and other fast moving animals. That is, the idea that from their subjective perspective, they move about as fast as we do from our subjective perspective. So when we try to brush away a fly, they see a hand coming at them as slowly as we would see a tortoise approaching us, and easily dodge away.
posted by paleyellowwithorange at 7:46 PM on September 23, 2013

It's not really clear what the connection should be between the flicker fusion rate and the phenomenal "rate" of conscious experience. We might think that consciousness shouldn't be any "slower" than the CFF, because otherwise the fast refresh of visual perception is being "wasted." But that seems wrong, because visual information can be processed without becoming consciously available at all. There are probably bottlenecks in conscious visual processing that are much slower than 60hz. We might think that consciousness shouldn't be any "faster" than the CFF, but experiments in humans suggest that phenomenal conscious experience can "speed up" without any change in visual processing. So CFF doesn't seem to offer either a floor or a ceiling for the subjective rate of conscious experience.

Meanwhile, other research seems to show that subjective time experience is not clearly connected to any obvious perceptual facts. For example, the experience of time "slowing down" at crucial moments does not seem to correspond with any obvious cognitive or perceptual process speeding up. What it does correspond to is unknown, but well-informed speculations seem to have nothing to do with visual refresh rate.
posted by grobstein at 7:52 PM on September 23, 2013 [3 favorites]

I once went to a talk about how whales experience the passage of time. Things went off the rails when the speaker started talking about how whales, unlike us, experience time as moving at the rate that it actually objectively flows.

(Which prompted my friend to crack, "Save the whales, while there's still time!")
posted by painquale at 8:10 PM on September 23, 2013 [1 favorite]

I feel like I figured this out when I was ten years old by watching dragonflies and my pet dogs and then thinking about dinosaurs.
posted by penduluum at 8:13 PM on September 23, 2013 [2 favorites]

Time flies like an arrow. Fruit flies like a banana.
posted by gwint at 8:15 PM on September 23, 2013 [5 favorites]

But from a fly’s point of view, does its life actually seem that much shorter?

Fly's perceive time?
posted by whyareyouatriangle at 8:21 PM on September 23, 2013 [1 favorite]

So from a cheetah's point of view it's just strollin' after that gazelle.
posted by George_Spiggott at 8:28 PM on September 23, 2013

So from a cheetah's point of view it's just strollin' after that gazelle.

Yes, but that's different - that's just because of time dilation from the relativistic speeds.
posted by anonymisc at 8:39 PM on September 23, 2013 [2 favorites]

my cat has a keen sense of time. The dog does not. the cat knows when her breakfast and supper are due. My dog has no clue about these things. If I leave for 10 minutes or several hours, the dog has no idea. The cat gives me a general "f ck you" look...regardless.
posted by shockingbluamp at 10:02 PM on September 23, 2013 [1 favorite]

This appears to be the paper mentioned. (Paywall free.)

Despite having pondered a much cruder version of the same question here a while back, I can't help but wonder if visual perception really captures what we mean when we talk about perceiving time. Still, a very interesting result!
posted by eotvos at 1:21 AM on September 24, 2013

"I've only got 24 hours to live and I'm NOT going to waste it here!" - A Bugs Life
posted by BlerpityBloop at 7:28 AM on September 24, 2013

There are many interesting things to say about that paper, but at the moment my favourite is that one of their citations is to a Dr D'Eath. Awesome.
posted by metaBugs at 7:55 AM on September 24, 2013 [1 favorite]

People perceive the passing of time because they are aware of their own mortality and the inevitability of their death.
posted by Thorzdad at 8:11 AM on September 24, 2013

There was quite an entertaining interview with Kevin Healy on CBC last week. Sorry, you'll have to ff to somewhere in the middle to find it...
posted by sneebler at 8:12 AM on September 24, 2013

Thorzdad, that's a bit of a stretch for me. My understanding is that there are various processes and neural circuitry that process all the different signals we're ultimately aware of, but none of this depends on our personal experience of consciousness, or a particular thought or belief.

Hence the emphasis on becoming intimate with death in some forms of Buddhism. Their take on it seems to be that we don't naturally take our mortality seriously enough, partly because our nature is to ignore our mortality, at least till we're past our twenties.

One of the more intriguing things I've heard in the last while is that our (human, in case there's anyone reading this who isn't...) consciousness is ~ 0.25 sec behind events in the real world. So some part of our processing power is used to predict the motion of things in the real world, and to create the impression of a seamless whole, even though it can be demonstrated that the brain is actually perceiving the time difference between events in the real world and internal responses. Which is totally cool.
posted by sneebler at 8:26 AM on September 24, 2013

I always just assumed this based on the whole "summer vacation lasted forever when you were a kid" notion and also because mushrooms.

One of the more intriguing things I've heard in the last while is that our (human, in case there's anyone reading this who isn't...) consciousness is ~ 0.25 sec behind events in the real world. So some part of our processing power is used to predict the motion of things in the real world, and to create the impression of a seamless whole, even though it can be demonstrated that the brain is actually perceiving the time difference between events in the real world and internal responses. Which is totally cool.

There's a great book that covers this called "The User Illusion" which at one point makes the argument that sometimes the mind "replays" things that initially happen outside of our consciousness in order to keep the timeline straight.
posted by billyfleetwood at 8:56 PM on September 24, 2013

I once went to a talk about how whales experience the passage of time. Things went off the rails when the speaker started talking about how whales, unlike us, experience time as moving at the rate that it actually objectively flows.


This seems to be a confusion that a bunch of people in philosophy have. This paper by Skow seems to be taking aim at it but I haven't read it.
posted by grobstein at 1:32 PM on October 9, 2013