Add this to the list of things you never thought you needed to see until you actually saw it: a praying mantis rocking miniature, old-school 3D glasses. A research team from Newcastle University outfitted the insects with the tiny glasses (green and blue lenses attached with beeswax) to study whether the invertebrates have 3D vision. They believe their findings may help determine new algorithms for 3D depth perception in computers, which in turn could improve visual perception in robots.
Until recently, all of our knowledge of how stereopsis works, a.k.a. 3D vision, came from studies of vertebrates. In the 1980s, a researcher named Samuel Rossel studied 3D vision in mantises but, because the test only used prisms and occluders, he could only show the insects a limited set of images. This new study definitively proves that the bugs see the world with 3D vision.
“Better understanding of their simpler processing systems helps us understand how 3D vision evolved, and could lead to possible new algorithms for 3D depth perception in computers,” said study leader Jenny Read, a professor of vision science, in a news release. “Despite their minute brains, mantises are sophisticated visual hunters which can capture prey with terrifying efficiency. We can learn a lot by studying how they perceive the world.”
When Read and her team first went to test the 3D vision of the mantises they tried using the sort of 3D tech that humans use — circular polarization that separates the two eyes’ images — but because glasses were able to separate the images correctly for the bugs. So they took a cue from the 3D glasses of the 1950s, the sort of blue and red lenses you can still find attached to comic books, switched it to blue and green because mantises have a hard time seeing red light, and bada bing they had a working pair of glasses. Very, very small glasses — each filter was about seven millimeters in length.
After a preliminary 24 hours of the glasses in place, the researchers hit the mantises with stereoscopic illusions, 10 trials with three disparity conditions. An image of a “spiraling disc target” on a screen didn’t elicit a response from the insects in 2D. But when the images were shown in 3D, the mantises struck at them. This proved that mantises actually use 3D vision, and constitutes essentially the first definitive test of 3D vision in invertebrates.
In Scientific Reports the research team writes that understanding stereopsis in “a system as simple as an insect” could carry a multitude of implications — it could potentially “provide new insights about human vision, reveal the convergent evolution of neutral algorithms and inspire the development of simple, robust stereo algorithms for robotics.” With further research, they hope to find out whether the novel mechanisms that evolved in mantises could be copied for robots — an essential feature for robots tasked with jobs that require them to sense depth, like the Curiosity Rover.
Now if only we could take the mantises to see something like The Deadly Mantis at IMAX, that’d be really meta.