The praying (preying!) mantis has forward-facing eyes, which in higher animals means (generally?) stereoptic vision. A mantis ‘strikes’ at the image of a dot moving through a polka-dot field. Nityananda & colleagues put blue/green filters on them with beeswax (mantises don’t see much of red light). The mantises struck at an illusory moving dot evidently perceived as ‘floating’ in front of the field also projected on the screen.
I omitted to mention two aspects without which this report must seem not very significant.
The mantis strikes when the ‘prey’ dot is perceived as being about an inch away. The screen on which the ‘3D’ field and dot are projected is at a greater distance, a distance at which the mantis would not strike. Therefore, the mantis is resolving the disparate dot images, one in each eye, into a perception of an object in striking distance. The mantis is doing this with a nervous system much simpler than was expected to be capable of this.
Naturally, the movement of the two dots is synchronized, e.g. both moving upward at the same rate so that they are resolved into a ‘foreground object’ moving upward. However, when the two dots were moved in opposite directions, the mantis still perceives and strikes at a moving foreground object.
From this they conclude that the mantis eye and nervous system resolves depth perception in a way that is different from the way in which vertebrate predators resolve depth perception, and they surmise that learning how they do this may be useful for robotics.
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On Fri, Feb 9, 2018 at 4:42 PM, Bruce Nevin bnhpct@gmail.com wrote:
The praying (preying!) mantis has forward-facing eyes, which in higher animals means (generally?) stereoptic vision. A mantis ‘strikes’ at the image of a dot moving through a polka-dot field. Nityananda & colleagues put blue/green filters on them with beeswax (mantises don’t see much of red light). The mantises struck at an illusory moving dot evidently perceived as ‘floating’ in front of the field also projected on the screen.