How Animals Perceive Time

Marine predators—such as sharks—need to see faster than land-bound animals in order to catch fish, which are constantly moving.

How we humans perceive time is a fascinating and intriguing topic. We know that we can see colors, hear sounds, smell odors, taste flavors and feel textures. Some aspects of the world, then, can be perceived through one of our five, basic senses.

Other things, however, such as shape, are discerned through more than one sense. But what sense or senses do we use when comprehending time? It is certainly not associated with one, particular sense. It would seem odd to say that we see, hear, smell, taste or touch time passing. And even if all our five senses were prevented from functioning for a while, we would still be able to notice the passing of time through the changing patterns of our thoughts. Perhaps, then, we have a special faculty, distinct from the five senses, for detecting time. Or, as seems more likely, we notice time through the perception of other things.

Researchers tell us that the nature of time is rooted in our bodies. In science-speak, “Constellations of impulses arising from the flesh constantly create our interoceptive perception and, in turn, the unfolding of these perceptions defines human awareness of time.” If that seems a bit complicated, from my own experience, I can tell you simply that feeling emotions such as awe slows down time and getting older seems to make it go by faster and faster.

Dragonflies were able to detect visual changes at 300 times per second. That is significantly faster than what humans can do: 65 times per second.

Another engaging aspect of time perception is how quickly we can do it. And new research reveals that the animals that can perceive time passing the fastest are those that can fly, are small or are marine predators.

Time perception: speedy salmon and slow starfish

In brand-new research that as of December 2022 has yet to be published, scientists at the University of Galway in Ireland analyzed the rate at which 138 animals perceive changes in the world, known as temporal perception. The researchers found that animals with fast-paced lifestyles have visual systems that can detect changes at higher rates.

The authors of this study, which is the largest of its kind to date, analyzed data collected from numerous studies which measured time perception using flickering-light experiments. Animals were shown pulses of light, which started slowly and then sped up. There comes a point when the light is flashing so quickly that it looks as though it is on permanently. Carefully placed, brain electrodes—called electroretinograms—revealed when this moment occurred and recorded the rate at which the optic nerve sent information, in turn measuring how fast an animal can detect the rate of the flashing. This is known as “critical flicker fusion frequency.”

In vertebrates, pied flycatchers—birds slightly smaller than house sparrows—have the fastest eyes. They see visual changes at 146 times per second, or at 146 hertz.

The results of the University of Galway study showed that species such as blowflies and dragonflies were able to detect changes at the highest rate, with vision that could handle 300 hertz (which means that they were able to see changes in their environments 300 flashes or times per second). That is significantly faster than what humans can do, which is to see at 65 hertz. In vertebrates, the fastest eyes belonged to the pied flycatchers, who could see at 146 hertz. Salmon clocked in at 96 hertz and dogs at 75 hertz. The slowest eyes belonged to crown-of-thorns starfish; they measured at 0.7 hertz (three flashes every four seconds, or less than one per second).

In the starfish’s world, then, everything is just a blur. The animal’s temporal perception may be so slow because it is an herbivore; it doesn’t need to strike fast to get a meal. A tasty coral polyp will be in the same place even if it takes the starfish more than a second to find it. But a marine predator—such as a shark—on the other hand, needs to see faster to catch fish, which are constantly moving.

On average, if you fly, you see faster. Flying animals detect light changes at a faster rate than land-bound animals, likely because they need to be able to sense changes around them quickly to avoid collisions.

Salmon clock in at 96 hertz for seeing changes in their environments; faster than us, but much slower than dragonflies.

In essence, fast-moving animals—especially small ones, creatures that fly and top ocean predators—perceive time more quickly than others. That is, they can process more frames per second than slow-moving animals lower in the food chain, such as starfish.

The researchers say that having fast vision helps a species detect rapid changes in the environment, which is very useful if you move quickly or need to pinpoint the trajectory of moving prey.

Quirky finding: quick when aquatic and tardy when terrestrial

One unexpected finding from this research is that many terrestrial predators have relatively slow time perception compared to aquatic predators. This difference could be because in aquatic environments, predators can continuously adjust their position when lunging for prey; while in terrestrial environments, predators that lunge at prey, such as a jumping spider, are not able to make adjustments once they’ve launched.

Time perception certainly raises many intriguing puzzles, including what it means to say we perceive time. Our dogs see at 75 hertz.

Having fast temporal perception is energetically costly and limited by how quickly neurons linked to retinal cells in the eye can recharge, so not all animals have it. Those that don’t require rapid vision use this energy for other requirements, such as growth or reproduction.

Changes afoot: differences within us and our environment

Of course, variation in time perception also occurs within species, including in humans. Some studies even suggest that in football, goalkeepers see changes at a higher rate. And, coffee can temporarily boost this by a small amount.

It is hoped that the fact that a species’ perception of time is linked to how fast its environment can change will help us understand predator-prey interactions. It may even aid us in discovering the aspects—such as light pollution—that affect some species more than others.

The slowest eyes belong to crown-of-thorns starfish. These herbivores measured at 0.7 hertz. ©Kris Mikael Krister, flickr

This perception research does make me wonder, especially with the rapid changes in the climate that we’re now seeing, if our sense of time will change—and our years will pass by even faster.

Here’s to finding your true places and natural habitats,

Candy