PARIS - Praying mantises sporting tiny 3-D glasses — held in place with beeswax — have revealed a new kind of “stereo” vision that may help improve robot sight, researchers said Thursday.
Sporting two teardrop-shaped, light-filtering lenses in lab experiments, the insects lashed out at special 3-D film images of tempting prey, a team of scientists said.
Scientists then observed reactions to more complex images, and learned that mantis vision works very differently from ours.
Humans can naturally judge depth when shown a still image. However, in mantises, such 3-D perception activates when there is movement.
“Mantises only attack moving prey, so their 3-D doesn’t need to work in still images,” said Vivek Nityananda of Newcastle University, one of the authors of a study published in Current Biology.
“We found mantises don’t bother about the details of the picture, but just look for places where the picture is changing,” he said in a video explaining the experiment.
This was the case even when each eye looked at two completely different images — an ability humans don’t share.
According to fellow researcher Jenny Read, this is an efficient method of 3-D vision and could have implications for algorithms used in machines such as drones.
“Current machine stereo algorithms require a lot of computing power,” she said.
“Reducing the amount of computer power necessary means smaller, lightweight robots could use mantis stereo algorithms to detect depth.”
Also known as “stereopsis,” 3-D or stereo vision helps humans and other creatures determine the distances to objects we see.
Each eye sees an object at a slightly different angle, but the brain merges the two images together and uses the difference to calculate how far something is.
Other animals with this ability include monkeys, cats, horses, owls and toads, said the research team.
The mantis is the only insect known to have stereo vision. But, given its tiny brain, scientists have long suspected it must involve a simpler process.
To test this, the team created special, tiny 3-D glasses out of filters for light in the blue and green spectral range, and used beeswax to fit them to 10 adult insects.
The experiment revealed that mantis stereopsis “uses a fundamentally different computational algorithm,” they said.
“Thus, while there is no evidence that mantis stereopsis works at all with static images, it successfully reveals the distance to a moving target.”