Time flies, unless you’re a fly

 
 

Following a recent study in Trinity College Dublin into animals’ ocular ability to process light, Ross McKeever highlights the potential advantages and disadvantages of perceiving time slower than humans

We all know that the early bird catches the worm, but it’s a lesser-known fact that a bird’s worm catching skills may be enhanced by an ability to see in slow motion. That’s right, birds see in slow motion.

This fascinating insight into the predation habits comes from a new study that has shown that animals tend to perceive time differently to humans. The study revealed that smaller animals are able to detect movement on a finer time scale to larger animals. Essentially, smaller animals observe the world at a higher frame rate and in a similar fashion to a slow motion camera.

Obviously, time travels at the same speed regardless of whether or not you have paws or wings, but smaller animals tend to perceive everything as if it were moving slower. This is because these animals have brains that can process images far quicker than human brains, and their eyes send updates back to the brain more frequently.

To give this observation a numerical context, the average human has the ability to see at a rate of around ten frames per second. In stark contrast, some species of flies are capable processing 40 images a second instead, and so time seems to pass much slower for them.

While this does mean that the flies see everything as if it were a slow motion cut from the Matrix, it also means that they would not be able to watch the Matrix, because films are usually shot at 24 frames per second. Since flies are able to see more frames per second, they would see a slideshow of flashy images instead of a preachy movie. That’s just one of the disadvantages of being a fly.

This confounding discovery was published recently in the long-standing journal Animal Behaviours. The lead writer of the study, Kevin Healy, of the Department of Zoology in Trinity College Dublin, used a technique called critical flicker fusion frequency to help measure the speed at which each animal’s eyes could process light.

This method tests the lowest frequency of flashing that a flickering source of light can be seen as a constant beam by an animal. The team tested a wide variety of species with this method, including rodents, eels, lizards, chickens, dogs, cats and leatherback turtles.

After this rigorous testing process, Healy and his team came to the conclusion that small animals with high metabolic rates saw the world at the highest frame rate. The pigeon, the starling and the golden-mantled ground squirrel proved to have particularly fast visual systems.

By comparison, woodlice were not even capable of seeing at half the frame rate of humans, despite their small stature. Worse still, the European eel sees only a quarter of the frame rate humans do.

The study not only reveals which animals have the best visual systems, but also briefly attempts to explain why certain species evolve to have powerful visual systems and why other species don’t. Healy’s study notes that smaller animal’s may have acquired powerful visual systems to become more aware of possible predators and prey.

Healy himself states, “The ability to perceive time on very small scales may be the difference between life and death for fast-moving organisms such as predators and their prey.” Animals have to be fast to avoid predators, scavenge food and to survive in general. As the old saying goes, the early bird catches the worm, but the late bird dies of fatal gastroenteritis brought on by malnutrition.

The study also claims that an animal’s maneuverability may determine whether or not it requires a powerful visual system. As larger animals aren’t very maneuverable, they don’t require a powerful visual system, as they wouldn’t be able to respond quickly enough to what they see anyway. Smaller animals are more maneuverable and can swiftly take advantage of slow motion vision.

One insect proved to be an unprecedented exception to this rule. The tiger beetle is an incredibly fast and maneuverable predator, but its eyes take in surprisingly little visual information. This means the insect can run faster than its eyes can keep up, resulting in a stop-start approach to hunting, as it has to frequently re-adjust its focus to see its prey.

Although this study focuses on animals, and in-particular vertebrates, its most interesting elements are its possible implications for people. The study does show that human’s visual capabilities vary depending on the person. For example, a professional tennis player is much more proficient at absorbing visual information than the average Joe.

On top of this, the study also revealed that younger animals perceive time differently to older animals. If this is also true for humans, then it could explain why time seems to travel quicker as we get older. This would also account for young children’s constant and interminable hyperactivity.

The study suggests that younger people see at higher frame rates than older people, but that height differences between individual people do not make a difference. So no, Bono and Danny DeVito do not see in slow motion.

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