How the brain decides what's real | Nadine Dijkstra

[00:00:00]One hypothesis that [music] we've been entertaining is that this reality monitoring, so deciding whether something is real or imagined, is [music] a function that your brain needs to develop. Maybe kids just don't have a reality to monitor yet. So for them, whether they are making it up or whether it's really there is kind of the same.

[00:00:22]>> Nadina [music] Dystra, welcome to how the light gets in.

[00:00:24]>> Thank you. Thank you for having me. So you are a cognitive neuroscientist uh and you lead imagine reality lab. Um so many people these days uh like to argue that reality is a controlled hallucination created by the brain. What do you make of that view?

[00:00:40]>> So I think using the word hallucination is maybe a little bit um it's not helpful I think because it makes it sound like it's like something is wrong and it's something you have to do something about. Um, so in that sense, I think that word itself is not helpful.

[00:00:54]But I do, you know, I do as an earth scientist, we know that the brain fills in what we perceive as reality. It kind of constructs our reality in an active way. We're not just passively perceiving reality like our eyes or a camera. So in that sense, yes, we are imagining our reality, but I wouldn't use the word hallucination.

[00:01:12]>> Imagining. What? So what's the difference between imagination and hallucinating? Sorry. So hallucinating just something's wrong, you say?

[00:01:19]>> I think that's what it is. So um it suggests something is wrong and and the way that we we imagine our own reality is usually in very efficient and it's adaptive. It's our brain has developed this way because it's a very efficient way of processing the information that's out there in the world. So we don't have to start from scratch every time we get signals into our eyes but we can use our prior knowledge to kind of fill in the gaps. Um and it's it's usually it works well and usually it goes right. So >> okay. So all is all of reality imagined then or is just parts of it?

[00:01:49]>> Well, as a narrative scientist, I don't say anything about what reality is. I just say how we perceive reality. Uh the way we perceive reality is a combination by what comes into our senses which is based on you know things that are actually out there in the world. But then how we interpret and perceive it is then also uh influenced by our prior knowledge and expectations.

[00:02:08]>> So at no point we come in contact with reality.

[00:02:12]>> I mean our senses get signals from reality. Yes.

[00:02:16]>> But is is that kind of fundamental reality is or or is that the reality that >> we perceive is created?

[00:02:21]>> Well, again, as a neuroscientist, I don't say what fundamental reality is. I don't know what fundamental reality is.

[00:02:26]I don't know what that question means.

[00:02:28]Uh but I do know that the way we perceive reality is something that's constructed by our brain.

[00:02:33]>> Okay. Um and so just is is there a kind of self-reflective problem uh there?

[00:02:38]Because isn't that thought itself a creation of your brain? And therefore, >> Exactly. That's why I'm very careful to say if I could say anything about what reality is. What I can do is measure what go what goes on in your brain when you decide whether something is real or not. For example, so we've done experiments where we ask people to imagine things and then sometimes if they imagine something really really vividly they say it's real. Well, we know nothing is out there in the world.

[00:03:02]So we know that in that case that's that is a hallucination because it's incorrect. But we can really look at what happens in your brain when you decide whether or not something is real.

[00:03:10]And that's what I am interested in. Not about whether it's real or not, but about how your brain decides whether something is real.

[00:03:16]>> Okay. And by what does real mean? Real means kind of uh confirmed by other people.

[00:03:22]>> It's what it feels like for you, right?

[00:03:24]So, so how do you decide whether something is real? It's because it feels real, right?

[00:03:30]>> But but you you saying uh something if something isn't there, it's not real.

[00:03:34]But can there be phenomena that appear only to my mind or to someone's mind?

[00:03:41]Yeah.

[00:03:42]>> Yeah. I guess so that's a good point.

[00:03:44]And I think reality in that sense exists a little bit on a spectrum where what we now see we can kind of agree on that that's black and like what I'm wearing is orange and all of those things. But then there's this there there's a spectrum where as you start to diverge more and more from what people agree on, you maybe becomes less and less real in that sense. But there's a social a social definition of real, right?

[00:04:05]>> Which is >> Yeah. because lots of people who have hallucinations uh on psychedelics, for example, kind of think that they're more real or more true than the reality that we see. What do you make of that?

[00:04:15]>> I don't see why that would be the case.

[00:04:16]It's still their brain interpreting signals coming into their senses. I don't I don't I don't see any argument of why their brain on psychedelics would interpret those senses as more real than than a a non-sychedelic brain. Mhm.

[00:04:32]>> And so is is does this rely on kind of a physicalist notion of consciousness, do you think? And if so, what's your kind of answer to the hard problem of consciousness?

[00:04:42]>> What's my answer to the hard problem of consciousness? That's your question.

[00:04:44][laughter] >> I mean, it seems kind of um embedded a little bit cuz you're saying kind of uh reality or we perceive just uh electrical signals in the brain. All perception just is uh electrical signals in the brain.

[00:04:58]>> Yeah. But that seems to be going that seems to have >> so I think I do have an implicit physicalist or materialist philosophy but it's not something that I would I would I would defend until the end. It's just something that I a working assumption. So I look for physical correlates of subjective experiences.

[00:05:15]>> That's yeah >> so obviously AI is very big right now.

[00:05:19]Uh I is the is the brain a computer in your view or is uh something non-mputational about the brain?

[00:05:25]>> Yeah. I think thinking about the brain as a computer is useful. I think it allows us to solve some problems and see what might go wrong when people have symptoms that are bothering them. So I think it's a useful model of the brain.

[00:05:37]I don't know if it's a complete model or a completely accurate model. I also don't know that if we would simulate the brain in a computer if that simulation would be conscious. It's kind of like if you simulate a rainstorm is not wet.

[00:05:50]Right. So I think that's that's where philosophy would come in for me. But I do think it's a useful model. Yeah. M >> what does the future of neuroscience look like with AI uh embedded? Obviously kind of Musk has this neurolink going on. Um I mean what what's the future of neuroscience uh and the AI connection uh with that?

[00:06:09]>> So I think always neuroscience and NI have been super intimately linked. So AI kind of was inspired by neuroscience by by cognitive science back in the day when we couldn't measure brains. We just thought about how thinking would work and then that led to inspiration of neural networks and and I think now we're at the stage where there's a virtual cycle. It's not only that the brain inspires AI but AI can inspire the way the brain works as well. So we can we can run AI simulations to get inspiration of how specific kind of functions might be implemented in brains. And I think that's going to continue. It's going to be a mutually inspiring field. Um and I think it's it's also going to make some problems more efficient to solve. we can use AI to to generate more efficient analysis.

[00:06:53]So, yeah.

[00:06:54]>> What what would you say are the biggest problems facing neuroscience today?

[00:06:59]>> Well, the consciousness one is a pretty big one, but I don't know if that's a neuroscience problem at the moment or if that's a philosophical problem at the moment. It seems like a theory problem at the moment because um neuroscientists there was this really big project where neuroscientists wanted to just replicate the brain. They wanted to build the brain in a computer. But even if you've built the brain in a computer, you still have not solved the problem of consciousness. So I think those are Yeah, it's a it's a hard one, but that's I think that's one of the one of the interesting ones.

[00:07:25]>> Yeah. Do do you think that's coming?

[00:07:26]Kind of being able to build a brain in a computer. Maybe it won't be conscious, but could it do all the other things that brains do?

[00:07:34]>> Maybe. Yeah. I mean, I just went to Enders uh Senberg's talk and and we are getting closer to to to at least emulating some of the functions of brains in computers. Um I don't I don't see any like natural limit to that. And then the second question of whether that simulation would be conscious that's an independent question I think.

[00:07:53]>> Okay. Returning to imagination that h how crucial is imagination to human beings.

[00:07:59]>> So there's I I guess there's different definitions of imagination. the imagination that when I talk about when what your reality is imagined that's the kind of automatic filling in like you have this blind spot in your eye right where where your nerve leaves your eyeball and that you shouldn't see anything there but we always we don't have a have a gap in our perception that's imagination that's part is imagined and I think that's really crucial because that's essential to how we perceive the world then you have the the more creative imagination of being able to create new associations and new and new concepts and new new ways of thinking and I think that's crucial for for more kind of development in in a more broad sense of the word. Yeah.

[00:08:39]>> Is that kind of a something special about human beings or can animals do that and and how crucial is is it to kind of self uh consciousness in human beings that act of imagination?

[00:08:49]>> Um so I think some human humans some non-human animals can also generate offline perception. So they can they can like simulate for example there's rats running in a maze and they can simulate alternative paths to the ones that they've just taken. You could say that's a form of imagination. I guess the the the the extent of the creativity of that is probably less than in humans. Um self-consciousness as in being aware that you are a self or self-consciousness as in having a subjective experience.

[00:09:20]>> Uh self-consciousness in that you are aware that you're aware. They're aware that you're aware >> and then you have an idea of identity of yourself.

[00:09:29]>> So I guess in order to have an awareness of your of you as as a as a c as a being, you need to kind of be able to decouple your perception from the immediate environment. You should you should not just be like a response output thing. You need some kind of offline processing. You could call that imagination. Sure. And then yes, that's but that's kind we're stretching the concept a little bit here, I think.

[00:09:49]Yeah. And so and your research looks at how the brain distinguishes between reality and imagination and as I understand it it can't sometimes can't discipline those things.

[00:09:58]>> Yeah.

[00:09:58]>> What consequences does that have?

[00:10:01]>> Well, I mean I guess when it if it goes wrong too often so so what we've studied we've studied in healthy brains people who are otherwise completely functioning there's no no diagnosed disorder or anything and then and then under very specific circumstances we show that we can get them to confuse their mental imagery for perception. But I think that's because we're pushing the right circumstances and that's that's because we're showing that that's the way the system works. But it works well. Like it usually this is this is a function that that that works well usually. I guess the problem if if that if that goes wrong is people can develop things like psychosis or schizophrenia where they start to really decouple from the consensus of reality and then um I guess their behavior becomes dysfunctional and they can't function in our in our society anymore. That's that's the extreme end of that. Yeah, >> obviously. Well, maybe not obviously actually, but ch children seem to imagine more than adults. Guess why is that? Why do we lose that?

[00:10:55]>> That's a really good question. So, we've been thinking about this quite a lot.

[00:10:58]And one hypothesis that we've been entertaining is that this reality monitoring, so deciding whether something is real or imagined, is a function that your brain needs to develop. And we think it's something that relies on your prefrontal cortex, which is kind of the latest brain areas to develop. Maybe kids just don't have a reality to monitor yet. So for them whether they are making it up or whether it's really there is kind of the same because we know the brain processes those things similarly but just in adults we've we have this add-on solution that makes sure we don't we don't confuse the two but maybe in children that that actual function of reality monitor it just doesn't work that well yet that's our current hypothesis would >> would the world be a better place if we could imagine better as adults as we do as children >> if we could imagine better no I think that would lead to a lot of dysfunction because we won't be able to keep it apart from reality Right. So I think we need as a functioning societ so society to kind of diverge on or like to get at at a shared reality that we can agree with in order to to you know to live functionally.

[00:11:57]>> Isn't imagination kind of crucial to any possible future though? You know we can't build a future without first imagining. I guess >> that's true. Yeah. Yeah. That's true. I think that's true. But I think there's a difference between having extremely good imagination and having imagination that's useful. I think the the imagination that's most useful is is pretty good but not too good. I think that's uh that's what we need. [music] Yeah.

[00:12:19]>> Wonderful. Nadina, wonderful to meet you and thank you for coming to Hala.

[00:12:22]>> Thank you. [music] [music] [music]