But the really tricky part is how do we go from what the mind does, from cognitive principles, to what the brain does, to neuro principles? When we start to bridge this divide between the mind and the brain it becomes difficult for us to make those connections directly. For example, let's consider a simple experiment in which people were given a set of sentences, some of them easier and some of them more difficult, and asked to make grammatical judgments about them. What turns out that when those sentences are more complex, what happens is, there is what's called homologous activity, activity in the right hemisphere that occurs for the more complex sentences that doesn't appear for the simple sentences. We can think of this as a form of neural efficiency. The idea is that, as people become better at a task their brains become more efficient. And you might think of this in terms of language proficiency, right, or expertise. And in fact there has been some work looking at this within the expertise literature, to consider how does expertise develop. And when we look at the brain and we think about this, specifically Noigh, Bower and Fink looked at the nature of psychometric IQ. That is, how people perform on psychometric tests that measure IQ. And what they found was that, in general, those who performed better seemed to have, not only less activity, but in fact, when they were given novel tasks they would begin to show activity in the frontal lobes. So the frontal lobes would come online. And they would function and act, and become active in more difficult novel types of tasks. Those with lower psychometric IQ did not show, necessarily, as much activity. And specifically, there was a synchronisation between the left frontal lobe and the parietal lobe. So why would this occur? Well, the idea is that under easy conditions, efficiency rules. Right? People who are more expert at a task can do it better. But under novel, difficult conditions, then we have to have other systems to come online to aid and help in solving this new problem that requires synchronization. And finally synchronization of areas might also signal adaptability, that is how people adapt to certain different types of tasks under conditions that differ. Chantel Prat and Marcel Just have discussed this quite a bit considering how efficiency, synchronization and adaptability might help to account for how the brain functions. But notice that, what we're talking about is a set of tasks and we're talking about how the brain and people adapt to these different tasks. So what clearly emerges from this literature is that there's not a clear correspondence between brain activity and what task someone is doing. When I say clear is that, as tasks become more difficult, they require the engagement of larger and larger brain circuits. There is one interesting aspect of this, and you might remember when we talked about the expertise literature and the fact that Anders Ericson has noted that experts don't differ from novices in IQ, and the question is why is this? Well, Noight, Bower and Fink have somewhat of an answer for that. Which is that, when experts begin at a very young age to engage in a task, they actually bypass the frontal lobes. So in fact, a lot of expertise affects for those who learn early in life appear actually in the parietal lobe. And we could think about this in a very interesting way. Why is early learning so good? Of course when it's continued across time, because we did show examples of people that are cut off from their first language, and then don't continue to develop. But why is that early learning so strong? Well, in part it's strong because the frontal lobes aren't up and running yet. And in fact, the parietal lobes and other more posterior regions can take over a function, and so they are no longer reliant on frontal lobe function. They become so automatic that people actually would rather not think about them than think about them.