New international study co-authored by University of Galway researchers shows that how animals live and move determines how quickly they see the world

Animals do not just see the world differently from one another, they experience time itself at dramatically different speeds, researchers have revealed.

The major new study shows that the speed at which an animal lives and moves strongly predicts how quickly it can visually process the world around it.

The team of scientists - a collaboration between the University of Galway and Trinity College Dublin - analysed visual perception across 237 species in the animal kingdom, from insects and birds to mammals and marine life.

The findings, published in the international journal Nature Ecology & Evolution, provide the strongest evidence to date that ecology and evolution shape how animals perceive time.

The researchers found that that species with fast-paced ecologies - such as flying animals and “pursuit predators”, which chase fast, manoeuvrable prey - have much faster visual perception than slow-moving or sedentary species.

            Dr Kevin Healy, co-author and Head of the Macroecology lab at the University of Galway’s School of Natural Sciences, said: “These results support a long-standing idea known as Autrum’s hypothesis, which in simple terms states that sensory systems evolve to match an animal’s way of life. What’s new is that we demonstrate this pattern across the entire animal kingdom, not just within small groups of species.”

            Lead author Dr Clinton Haarlem, from Trinity’s School of Natural Sciences, said: “From a dragonfly tracking prey in mid-air to a starfish grazing slowly across the seabed, animals live in very different perceptual worlds. Our results show that these differences are not random. Instead, they are closely linked to how animals move, hunt, and interact with their environments.”

Measuring the speed of sight

To measure how quickly animals can process visual information, the researchers used a standard metric called “critical flicker fusion (CFF)”, which is the fastest rate at which a flickering light can be perceived as distinct rather than continuous. Higher CFF values indicate faster visual processing.

While humans typically perceive flicker up to around 60 Hz, some insects and birds can detect changes at more than 200 flashes per second, effectively experiencing a slower-moving world.

The team then tested how CFF relates to ecological traits such as locomotion, foraging strategy, body size, and light environment.

Among the key results were:

• Flying species have the fastest visual perception, with CFF values roughly twice as high as non-flying animals.
• Pursuit predators have significantly higher temporal resolution than species feeding on stationary or slow-moving food
• Light environment matters: species active in bright conditions generally have faster vision than those living in darkness or deep water
• In aquatic environments, smaller, more manoeuvrable species tend to see faster than larger ones

Dr Kevin Healy, said: “Species which live in low light environments and have slow lifestyles were found to have extremely slow visual systems. For example, the escolar, a deep sea fish, can see less than ten frames a second while deep sea isopods, a type of crustacean, can only see a couple of frames per second. For these species the world likely passes in a blur.”

Why perception speed matters

Fast visual processing allows animals to react to rapid changes, which is crucial for flight, hunting, and avoiding predators – but that comes at a cost. Rapid neural processing requires more energy, meaning high-speed vision is only favoured when it provides a clear ecological advantage.

The findings also raise concerns about the impacts of artificial lighting and flicker in human-modified environments.

            Dr Haarlem continued: “These findings suggest species with fast visual systems may be especially vulnerable to flickering artificial lights. This could affect their hunting success, navigation, and impact predator–prey interactions, particularly in birds and aquatic predators. Understanding how animals perceive time helps us understand how they behave, evolve, and respond to environmental change. It reminds us that the world we experience is just one version of many.”

By linking ecology, evolution, and perception, the study ultimately highlights how animals inhabit fundamentally different sensory realities even when they share the same habitat.

The full study in Nature Ecology & Evolution is available at https://www.nature.com/articles/s41559-026-02994-7

Ends