Jonathan Birch
speaker
151 appearances
1 recordings
1 series
first heard Oct 2024
last heard Oct 2024
Jonathan Birch’s voice in public audio — every appearance, attributed to the second.
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So I do think there's something inherently more impressive about experiments that do not simply provide two immediate stimuli and say, trade these off, but rather in some way rely on the animal's capacity for mental representation. And it's a similar story with the evidence from bees as well. That's what researchers have been trying to do. Sorry, tell us about the evidence from bees.
I was just thinking of Matilda Gibbon's experiments where they're inspired by Elwood's crab experiments. But bees don't have the shells that hermit crabs have. So you've got to test for the same thing in a different way. And so she came up with this setup where
They have a choice of feeders they can land on, and different concentrations of sugar solution are available at different feeders, and different temperatures of heat pad are there that they have to stand on to access the feeder. And so the question now is about a different kind of trade-off. Will they trade off when choosing which feeder to go to? How...
how high was the heat they had to withstand, and how sweet were the rewards that they can access. And again, a crucial part of it for Tilda was this thought that you want to look at their decisions when they're anticipating what they're going to experience at these feeders based on their memories.
Yeah, because when they're doing it, there is this possibility that, well, there is some integration of some kind going on, but it's just two immediate stimuli pushing against each other. But when they're making that choice in an anticipatory fashion, it's got to be some kind of representation of the risks and opportunities.
So, yes, not every critic is convinced by this kind of evidence, of course. But in a way, you're going after that critic who says these animals are just reflex machines. And because they're just reflex machines, there's no credible theory of sentience of any kind on which they're going to meet the conditions. And it's showing that that is not the case.
I think that's right, that they're prospectively modeling the environment and the rewards and the risks that it offers. And they have some way of weighing up those risks and rewards in a common currency. And that ties in with this quite longstanding idea that, well, that's kind of what sentience does for us.
That pain and pleasure, valence, states, they're the currency through which we make decisions and represent the risks and opportunities of our environment.
I mean, I think that's something that goes beyond sentience, much the same way that the inner monologue, et cetera, goes beyond sentience. It's something some sentient beings can do, but probably not all. I think that's going to be the case for counterfactual reasoning. Of course, it depends a bit on what we mean by that.
I think if you think of rats in a maze and the vicarious trial and error behavior that was observed by Tolman many, many decades ago and has been intensively studied, where they seem to pause at the junction in the maze and look both ways as if simulating what reward lies down each path
And then there's more recent studies that suggest that the hippocampus genuinely is doing that, that simulating, uh, you know, this is, it's not really counterfactual reasoning, or at least that would be a pretty tendentious description of it, but it's perspective simulation. Um, and I suspect that that capacity for perspective simulation is, is quite widespread among animals.
It's a hypothetical, right? It's possible futures that could be actual.
So there's no sense of, well, that didn't happen, but what if it had happened? So that bit's not there.
Well, I think Andrew Barron and Colin Klein have this paper about insects and the origin of consciousness. And another one called Insects Have the Capacity for Subjective Experience. And their case is based on the idea that what they have is this integrative model of the agent in space where they model the environment around them. That may be prospection on a very short timescale, I suppose.
And then it's largely an open question about prospection on longer timescales. Some of the most interesting evidence there is probably the Porsche spider evidence, where these are jumping spiders that hunt other spiders. And they're famed for this detour behavior. where you put them on a platform where they can see prey item in the distance and they can see two paths to the prey item.
One of them has a break in it. If they take that path, they will fall through it and they go from side to side. They seem to be inspecting the two paths. Then they climb back down off the platform. So the paths are out of sight and they nearly always choose the unbroken path. Um, leading to a debate about how on earth they do something like that.
And of course, one possible explanation involves perspective simulation, where they are in the brain modeling what will happen if they take each path.
Yes, well, and I think in the Porsche Spider case, what's lacking is the neural evidence that we have in the rats. So say if you have both, if you have the behavior and you have neural recording practically showing the simulation happening in real time, then that's probably as strong evidence as you're ever going to get. And we don't have that for the Portia spiders, but it's very suggestive.
Right. Yeah, that's part of what's so impressive. In a brain of, I think, about 60,000 neurons, so really, really small, less than 10% of the size of the bee brain by neuron count, They're doing something that dogs clearly fail to do.
I think we can't really talk with confidence about this because it depends very much on your theory of the brain mechanisms involved.
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