Vivec Nityananda and colleagues report some interesting experiments with “3D insect cinema”—basically augmented reality goggles for praying mantises . (Others have used VR to study insect behavior not relying on stereo vision.)
Mantises are monochromatic (as far as we can tell), but have highly effected movement detection and tracking, as witnessed by their hunting skill. With two huge, forward facing eyes, we might expect them to probably use stereo vision of some kind. In the last forty years, evidence has accumulated that mantises indeed do have stereo vision. But how do they do it?
This is an interesting question for several reasons. With their obvious visual equipment (I mean, look at them peepers!), mantises “ought” to use stereo vision. If they did not have stereo vision, then that would be an interesting puzzle to tackle, akin to the mystery of flightless birds. Proof that they do indeed use stereo cues is an interesting point, in itself.
Whatever the mechanisms are, they have developed independently from mammals and other species with stereo vision. As Nityananda et al. point out, we can compare mantis vision to humans, birds, and other cases “to explore whether nervous systems in vastly divergent evolutionary lineages have evolved convergent or divergent solutions to the same complex problems.” (p. 1) How many ways has this problem been solved throughout evolutionary history?
Additionally, “given the relative simplicity” of mantis nervous systems, whatever mechanisms they have evolved “might be easier to adapt into robotic or computational systems of depth-perception”. (p.1-2) Who knows what useful tips we might learn from mantis vision?
The research team adapted techniques used in human VR and AR to the mantis. First, they found that polarized filters did not work well for mantises. On the other hand, “anaglyph” 3D, as in old-style red/blue 3D glasses did work. So they “crafted miniature 3D glasses by cutting out pieces of filter, about 7 mm in diameter.” (P. 4), affixing a blue or green lens to each compound eye.
The results showed that the mantis responded to the visual illusions generated by these false stereoscopic pictures, striking at what appeared to be prey.
This is clever work, for sure, an opens the way to exploring this independent evolution of stereo vision. And it’s not just a “species appropriate” interface for mantises, it species appropriate AR!
But this study made me think about the questions I raised long ago .
When we conduct experiments on humans or “higher” animals, we take great care to avoid harm or unnecessary discomfort for the participants. In the case of VR or AR, we know that some people experience nausea, head aches, or other unpleasant effects. We would monitor them and remove the goggles to protect them.
How would we pursue this same ethical policy in the case of mantises? Do we know if these goggles (glued onto their eyes!) bother them? Whether the stereo illusions cause discomfort? How would we know?
No, I don’t know the answer.
Research ethics also demand that we not humiliate or degrade our subjects with the experimental activities. For example, we would be cautious asking questions about sexual experience, or presenting violent stimuli, because these might be unpleasant or embarrassing. We always have to balance what is needed to test the research question with what the participants may experience.
In the case of the mantis experiments, the behavioral measure involved tricking the participant into striking and missing what looked like prey. This is a core behavior of the mantis, and missing a strike is a serious thing indeed. Aside from the potential long term effects of messing with predatory behavior, is it justified to mess with the mind of the mantis in this way?
I think a case can be made that this experiment is ethical, at least based on what little we know about mantis minds. But I doubt that much thought was given to these questions, beyond the obvious notion that “it’s just an insect”.
The good news is that the techniques demonstrated in this study should enable more sophisticated studies of mantis behavior, which may lead us to understand them better, and perhaps refine our knowledge of how to treat them ethically.
Oh, and, of course, VR goggles mean we can now serve up Mantis porn, which, from what I understand of their love life, could be pretty extreme. : – )
- Robert E. McGrath, Species-appropriate computer mediated interaction, in Proceedings of the 27th international conference extended abstracts on Human factors in computing systems. 2009, ACM: Boston, MA, USA.
- Vivek Nityananda, Ghaith Tarawneh, Ronny Rosner, Judith Nicolas, Stuart Crichton, and Jenny Read, Insect stereopsis demonstrated using a 3D insect cinema. Scientific Reports, 6:18718, 01/07/online 2016. http://dx.doi.org/10.1038/srep18718
(Thanks to friend of the blog, Alan Craig for pointing out this study to me.)