Praying mantises are known to be one of the most capable predators in the insect world because of their use of a form of 3D vision called stereopsis. Despite being invertebrates, mantises have compound eyes that are capable of covering a larger field of vision as well as seeing a potential prey clearly even at close range.

Now, a team of scientists in the United Kingdom is trying to explore how the acute vision of mantises work in order to provide robot models with better visual perception of their own.

In a study featured in the journal Scientific Reports, vision science expert Jenny Read and her colleagues at Newcastle University developed a new pair of 3D glasses that are specially designed to test how mantises use stereopsis when hunting their prey.

While the device makes use of "old school" design, the researchers opted for a combination of blue and green colored lens instead of the usual blue and red ones because mantises are not capable of perceiving red light properly.

Read explained that even though mantises only have minute brains, they are highly adept hunters that use their vision to efficiently capture their prey.

By studying the simple processing systems of mantises, Read said scientists can have a better understanding of how 3D vision has developed. This could lead to the creation of new computer algorithms for improved 3D depth perception.

Fitting Mantises With 3D Glasses

During their experiment, Read and her team attached miniature 3D glasses on praying mantises using beeswax. The insects were then shown short video clips of other bugs moving around a computer screen.

When the mantises were shown videos of insects in 2D, they did not try to catch the bugs on the screen. However, when they were shown the clips of floating bugs in 3D, the mantises tried to attack them. The researchers believe this proves that praying mantises indeed use 3D vision whenever they hunt for prey.

Read and her team tried to use modern-day 3D technology used for humans in their test. These devices make use of circular polarization in order to separate the images that each eye sees.

When the researchers applied the technology to the mantises, it failed to produce conclusive results because the vision of the insects were so close to the screen that the 3D glasses were not able to correctly separate the two eyes' images.

"When this system failed we looked at the old-style 3D glasses with red and blue lenses," study co-author Dr. Vivek Nityananda, said"Since red light is poorly visible to mantises, we used green and blue glasses and an LED monitor with unusually narrow output in the green and blue wavelength."

Nityananda said their study was able to demonstrate how stereopsis or 3D vision works in praying mantises and how the technique can be used to provide insects with virtual 3D stimuli.

Read and her colleagues will now proceed with studying the algorithms involved in depth perception for insects in order to have a better understanding of how the vision of humans evolved. 

They will also try to develop new methods of applying 3D technology to robots and computers, similar to efforts by other scientists to develop new technology based on insect capabilities.

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