Ok, finally got around to writing about navigation. A few comments I have about this: -I agree that navigating known paths/areas is a fairly simple skill. However, if the animal increases the speed with which it traverses such areas it is usually taken as an indicator of becoming familiar with the route. If an animal always moves at a constant speed in a known environment, it may be an indicator that it is constantly in exploring without ever learning.
-The examples presented for navigating unknown areas in the Sentience Table are a bit less clear for me in terms of whether they reflect navigational learning or contextual conditioning. Mazes (as they are generally presented to humans) do seem a reasonable indicator of learning to navigate an unknown area, however, the way they are often used in insect studies means that they primarily test conditioning rather than navigational ability. For instance, the methods used to teach bees to navigate a maze in Zhang et al 2000, were:
Bees were trained to come to a feeder placed initially just outside the entrance to the maze. After they were marked, the feeder was moved slowly step by step through the maze, remaining for ∼1 h in each decision chamber.
As such, it seems to more of an indicator they learnt a series of choices they had to take quite slowly. Likewise, Zhang et al 1996 show bees learning symbolic cues to solve mazes (such as turn right if the wall is green) seem to be more of an indicator of rule learning. The Drosophila heat aversion paradigm developed by Ofstad et al is quite similar to the Morris water maze, and although this paradigm is a good test of visual-spatial memory (when the animal then quickly changes its position to the new cool point based on movement in the visual panorama), reaching the safe point should be solvable by a Type 1 Braitenberg vehicle (which does not seem to be intelligent). The examples of maze learning in cockroaches are perhaps a bit more like what humans generally associate with maze learning—I looked back through the references from Webb and Wystrach 2016 and found the original paper on maze learning in cockroaches, where roaches navigated an actual hot metal maze to find a cooler safe point, and it seems their speed and accuracy increased over time. Perhaps an issue is that maze learning is difficult to motivate insects to do in the same way that vertebrates do. For instance, I think it would be very hard to train a bee to enter a maze and search it for food—placing it (or the entire hive) at the centre seeing if they navigate out might be a better analogy (but I suspect this may just end up with them getting stuck in the corners). That said, I think it is fairly clear that central place foragers navigate unfamiliar territories, it’s just that I don’t find most uses of mazes to be particularly relevant. The fact that a honeybee hive can be moved to a forest and the bees will quickly forage on available flowers seems a good indication of their ability to navigate unknown areas, but I don’t know of anybody who has really tried to quantify this, it’s just taken as a given.
-When discussing spatial memory, it’s important to consider the distinction of traversing routes vs. having a map like memory. Traversing route (or things like traplining) implies that a set path can be learnt (indicated by landmarks or odometry) but not necessarily that different paths can be linked. However, map memory is taken to imply that routes are placed on a topographic representation in its memory and that an animal can then use this map to link points on known routes with a novel shortcut (that isn’t based on shared landmarks visible between the routes). This is quite controversial and hard to motivate insects to do reliably (as bees and ants tend to try to go to and from their nest on specific routes, but don’t usually jump between routes). I would place this higher than detouring in terms of navigational ability. Actually, I was surprised to see detouring as a navigational ability as I’d never thought about it much. However, I agree that ant work indicates detouring shows a degree of navigational flexibility between direct route following and map navigation. Unfortunately it’s probably quite hard to test detouring reliably in flying insects without building large 3D constructs, although some virtual reality work may have done this.
I’ve enjoyed looking through the criteria and evidence you’ve used in putting together the Invertebrate Sentinance Table, particularly in that its led me to think place my knowledge of invertebrate neuroscience in a consciousness framework. Feel free to get in touch if you’d like my opinion on any of your further work on this.
Hey Gavin. Once again, thanks for the wealth of insights and references! I have a few thoughts in response, but at this point it might be more valuable if we scheduled a videochat. I’m going to send you a message in a few minutes.
Ok, finally got around to writing about navigation. A few comments I have about this:
-I agree that navigating known paths/areas is a fairly simple skill. However, if the animal increases the speed with which it traverses such areas it is usually taken as an indicator of becoming familiar with the route. If an animal always moves at a constant speed in a known environment, it may be an indicator that it is constantly in exploring without ever learning.
-The examples presented for navigating unknown areas in the Sentience Table are a bit less clear for me in terms of whether they reflect navigational learning or contextual conditioning. Mazes (as they are generally presented to humans) do seem a reasonable indicator of learning to navigate an unknown area, however, the way they are often used in insect studies means that they primarily test conditioning rather than navigational ability. For instance, the methods used to teach bees to navigate a maze in Zhang et al 2000, were:
As such, it seems to more of an indicator they learnt a series of choices they had to take quite slowly. Likewise, Zhang et al 1996 show bees learning symbolic cues to solve mazes (such as turn right if the wall is green) seem to be more of an indicator of rule learning.
The Drosophila heat aversion paradigm developed by Ofstad et al is quite similar to the Morris water maze, and although this paradigm is a good test of visual-spatial memory (when the animal then quickly changes its position to the new cool point based on movement in the visual panorama), reaching the safe point should be solvable by a Type 1 Braitenberg vehicle (which does not seem to be intelligent).
The examples of maze learning in cockroaches are perhaps a bit more like what humans generally associate with maze learning—I looked back through the references from Webb and Wystrach 2016 and found the original paper on maze learning in cockroaches, where roaches navigated an actual hot metal maze to find a cooler safe point, and it seems their speed and accuracy increased over time.
Perhaps an issue is that maze learning is difficult to motivate insects to do in the same way that vertebrates do. For instance, I think it would be very hard to train a bee to enter a maze and search it for food—placing it (or the entire hive) at the centre seeing if they navigate out might be a better analogy (but I suspect this may just end up with them getting stuck in the corners). That said, I think it is fairly clear that central place foragers navigate unfamiliar territories, it’s just that I don’t find most uses of mazes to be particularly relevant. The fact that a honeybee hive can be moved to a forest and the bees will quickly forage on available flowers seems a good indication of their ability to navigate unknown areas, but I don’t know of anybody who has really tried to quantify this, it’s just taken as a given.
-When discussing spatial memory, it’s important to consider the distinction of traversing routes vs. having a map like memory. Traversing route (or things like traplining) implies that a set path can be learnt (indicated by landmarks or odometry) but not necessarily that different paths can be linked. However, map memory is taken to imply that routes are placed on a topographic representation in its memory and that an animal can then use this map to link points on known routes with a novel shortcut (that isn’t based on shared landmarks visible between the routes). This is quite controversial and hard to motivate insects to do reliably (as bees and ants tend to try to go to and from their nest on specific routes, but don’t usually jump between routes). I would place this higher than detouring in terms of navigational ability. Actually, I was surprised to see detouring as a navigational ability as I’d never thought about it much. However, I agree that ant work indicates detouring shows a degree of navigational flexibility between direct route following and map navigation. Unfortunately it’s probably quite hard to test detouring reliably in flying insects without building large 3D constructs, although some virtual reality work may have done this.
I’ve enjoyed looking through the criteria and evidence you’ve used in putting together the Invertebrate Sentinance Table, particularly in that its led me to think place my knowledge of invertebrate neuroscience in a consciousness framework. Feel free to get in touch if you’d like my opinion on any of your further work on this.
Hey Gavin. Once again, thanks for the wealth of insights and references! I have a few thoughts in response, but at this point it might be more valuable if we scheduled a videochat. I’m going to send you a message in a few minutes.