Animals don't just see the world differently from one another, they experience time itself at dramatically different speeds. That is according to a new study that considered 237 species across the animal kingdom, and which revealed that how fast an animal lives and moves strongly predicts how quickly it can visually process the world around it.
In research published in leading international journal Nature – Ecology & Evolution, scientists from Trinity College Dublin and the University of Galway show 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.
"From a dragonfly tracking prey in mid-air to a starfish grazing slowly across the seabed, animals live in very different perceptual worlds," said lead author Dr Clinton Haarlem, from Trinity's School of Natural Sciences and Trinity College Institute of Neuroscience. "Our results show that these differences are not random. Instead, they are closely linked to how animals move, hunt, and interact with their environments."
The findings provide the strongest evidence to date that ecology and evolution shape the tempo of perception across life on Earth.
Measuring the speed of sight
The researchers analysed data from 237 species from a wide range of groups, including insects, birds, mammals, and fish. To measure how quickly animals can process visual information, they 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
"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," said co-author Dr Kevin Healy, from the University of Galway. "What's new is that we demonstrate this pattern across the entire animal kingdom, not just within small groups of species."
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.
"These findings suggest species with fast visual systems may be especially vulnerable to flickering artificial lights," said Dr Haarlem. "This could affect their hunting success, navigation, and impact predator–prey interactions, particularly in birds and aquatic predators."
By linking ecology, evolution, and perception, the study ultimately highlights how animals inhabit fundamentally different sensory realities even when they share the same habitat.
"Understanding how animals perceive time helps us understand how they behave, evolve, and respond to environmental change," said Dr Haarlem. "It reminds us that the world we experience is just one version of many."
