Time passes faster for smaller, quicker animals

This time of year, as the days are short and the calendar winds down to a single page, it’s easy for many to ask “where did the time go?” Perception of time varies partially because time measurements are a social construct, but also due to biological difference- even for animals other than humans.

Some preliminary research presented at the annual meeting of the British Ecological Society on December 20 shows that the animals that perceive time the fastest can fly, are small, or are marine predators.

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The to-be published study looked at 138 species and analyzed temporal perception, or the rate at which they perceive changes in the world. The team found that animals who have more fast-paced lifestyles are equipped with visual systems that can detect changes at higher rates.

“Having fast vision helps a species perceive rapid changes in the environment. Such detailed perception of changes is very useful if you move quickly or need to pinpoint the trajectory of  moving prey,” said Kevin Healy, an ecologist from the University of Galway in Ireland, who presented the research.

Dragonflies were able to detect the changes at the highest rate, with vision that could see changes 300 times in one second, or 300 hertz (300 hz). This is much faster than humans, who can only handle changes 65 times in a second (65 hz).

Among vertebrates, the pied flycatcher, a small bird similar to a sparrow, wins the prize for the fastest eyes at 146hz. Dogs clocked in at 75 hz (quicker than humans) and salmon could see at 96hz.

At only 0.7hz, the crown-of-thorns starfish had the slowest eyes in the study.

One of the unexpected findings is that many terrestrial, or land-based, predators perceive time relatively slowly when compared to their aquatic counterparts.

According to Healy, “We think this difference may 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.”

Fast temporal perception takes a lot of energy and is limited by how quickly the neurons that are liked to retinal cells in the eye can recharge. For animals that don’t require such rapid eyesight, this energy is better used in reproduction or growth, according to the research.

[Related: How to slow down time because you’re not getting any younger.]

Not surprisingly, variation in the perception of time can also occur within species, including humans. Some studies suggest that goalkeepers in soccer/football can see changes at a higher rate and coffee can briefly give perception a small boost.

This analysis relied on the data from numerous studies that used flickering light experiments to measure time perception. In these experiments, a light is flickered and the rate at which the eye’s optic nerve sends the information to the brain is measured using electroretinograms. The electroretinograms in turn measured critical flicker fusion frequency, or how quickly an animal was able to detect the rate of a light flashing.

The research will help shed light on multiple aspects of an animal’s environment, namely how predators and prey interact with one another.

“By looking at such a wide range of animals, from dragonflies to starfish, our findings show that a species’ perception of time itself is linked to how fast its environment can change,” said Healy. “This can help our understanding of predator-prey interactions or even how aspects such as light pollution may affect some species more than others.”