Yes, your brain has much more processing power than anybody's laptop. But I think the people you quote are referring to the available general-purpose processing power.
Your visual cortex, for instance, packs a huge amount of processing power, but it's specialized for one task - processing visual information. You can't just tell it to crunch numbers and get a useful output, because it isn't built for that. Yes, there are clever tricks for employing your visual cortex in calculating big numbers, but even those don't take full advantage of it - the author of the linked paper says he was able to multiply two random 10-digit numbers together over a period of 7 hours. If you could use all the power in your visual cortex, you'd get the result instantly.
The brain packs a huge amount of power, but most of it is very specialized and hard to take advantage of, unless your task happens to be one similar to the domain that your brain has specialized circuitry for. Yes, with enough practice and the right tricks, people can learn to perform impressive feats of arithmetic and memory, so the circuitry is to some extent reconfigurable. But no human yet has managed to outdo modern computers in pure number-crunching. And getting even that far takes a lot of practice, so the circuitry isn't usefully available for most tasks.
We do have some processing power available for truly general-purpose computing. Given any (non-quantum) algorithm, a pen and some paper, you can simulate that algorithm with enough time. We had people do that before coming up with digital computers. But it's going to take a while, because your usefully available general-purpose computing power is very limited. In contrast, practically all of the laptop's processing power is general-purpose and usefully available - give it the same algorithm, and it's going to run through it a lot faster than you will.
From time to time I encounter people who claim that our brains are really slow compared to even an average laptop computer and can't process big numbers.
At the risk of revealing my complete lack of knowledge of neural networks and how the brain works, I want to ask if this is actually true?
It took massive amounts of number crunching to create movies like James Cameron's Avatar. Yet I am able to create more realistic and genuine worlds in front of my minds eye, on the fly. I can even simulate other agents. For example, I can easily simulate sexual intercourse between me and another human. Which includes tactile and olfactory information.
I am further able to run real-time egocentric world-simulations to extrapolate and predict the behavior of physical systems and other agents. You can do that too. Having a discussion or playing football are two examples.
Yet any computer can outperform me at simple calculations.
But it seems to me, maybe naively so, that most of my human abilities involve massive amounts of number crunching that no desktop computer could do.
So what's the difference? Can someone point me to some digestible material that I can read up on to dissolve possible confusions I have with respect to my question?