Charan Ranganath: evaluation

Transcript context

…Well, I think somebody once said to me that kind of loosely philosophically that the reason we don’t remember the first few years of life, infantile amnesia is because how traumatic it is. Basically the error rate that you mentioned when your brain’s prediction doesn’t match reality, the error rate in the first few years of life, your first few months certainly, is probably crazy high. It’s non-stop freaking out. The collision between your model of the world and how the world works is just so high that you want whatever the trauma of that is not to linger around. I always thought that’s an interesting idea because just imagine the insanity of what’s happening in a human brain in the first couple of years. You don’t know anything and there’s just this stream of knowledge and we’re somehow, given how plastic everything is, it just kind of molds and figures it out. But it’s like an insane waterfall of information. I wouldn’t necessarily describe it as a trauma and we can get into this whole stages of life thing, which I just love. Basically those first few years there are, I mean think about it, a kid’s internal model of their body is changing. It’s just learning to move. I mean, if you ever have a baby, you’ll know that the first three months they’re discovering their toes. It’s just nuts. So everything is changing. But what’s really fascinating is, and I think this is one of those, this is not at all me being a scientist, but it’s one of those things that people talk about when they talk about the positive aspects of children is that they’re exceptionally curious and they have this kind of openness towards the world. And so that prediction error is not a negative traumatic thing. I think it’s a very positive thing because it’s what they use, they’re seeking information. One of the areas that I’m very interested in is the prefrontal cortex. It’s an area of the brain that, I mean, I could talk all day about it, but it helps us use our knowledge to say, “Hey, this is what I want to do now. This is my goal, so this is how I’m going to achieve it,” and focus everything towards that goal. The prefrontal cortex takes forever to develop in humans. The connections are still being tweaked and reformed into late adolescence, early adulthood, which is when you tend to see mental illness pop up. So it’s being massively reformed. Then you have about 10 years maybe of prime functioning of the prefrontal cortex, and then it starts going down again and you end up being older and you start losing all that frontal function. So I look at this and you’d say, “Okay,” you sit around episodic memory talks. While they always say children are worse than adults at episodic memory, older adults or worse than young adults at episodic memory. And I always would say, “God, this is so weird. Why would we have this period of time that’s so short when we’re perfect or optimal? ” And I like to use that word optimal now because there’s such a culture of optimization right now. And it’s like I realize I have to redefine what optimal is because for most of the human condition, I think we had a series of stages of life where you have basically adults saying, “Okay”, young adults saying, “I’ve got a child and I’m part of this village and I have to hunt and forage and get things done. ” I need a prefrontal cortex so I can stay focused on the big picture and the long haul goals. Now I’m a child, I’m in this village, I’m kind of wandering around and I’ve got some safety, and I need to learn about this culture because I know so little. What’s the best way to do that? Let’s explore. I don’t want to be constrained by goals as much. dering around and I’ve got some safety, and I need to learn about this culture because I know so little. What’s the best way to do that? Let’s explore. I don’t want to be constrained by goals as much. I want to really be free, play and explore and learn. So you don’t want a super tight prefrontal cortex. You don’t even know what the goals should be yet. If you’re trying to design a model that’s based on a bad goal, it’s not going to work well. So then you go late in life and you say, “Oh, why don’t you have a great prefrontal cortex then?” But I think, I mean if you go back and you think how many species actually stick around naturally long after their childbearing years are over, after the reproductive years are over? With menopause, from what I understand, menopause is not all that common in the animal world. So why would that happen? And so I saw Alison Gopnik said something about this so I started to look into this, about this idea that really when you’re older in most societies, your job is no longer to form new episodic memories, it’s to pass on the memories that you already have, this knowledge about the world, what we call semantic memory, to pass on that semantic memory to the younger generations, pass on the culture. Even now in indigenous cultures, that’s the role of the elders. They’re respected, they’re not seen as people who are past it and losing it. And I thought that was a very poignant thing, that memory is doing what it’s supposed to throughout these stages of life.…

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