One of the reasons that I think adults often find it more challenging to learn new things than children is that adults generally possess quite a number of expectations about what should be easy for them. There are certainly other factors: adults already have a solidified framework for their preexisting knowledge; so, any new information must be fit into this framework somehow, and sometimes the fit may not be perfect. There are also brain growth and adaptation differences between the age groups—the brain culls unused neurons as a child develops, so certain capacities get cut if they are never utilized. Consequently, an adult who never, say, learned to speak as a child may lose that ability forever (there are numerous cases of so-called feral child who suffer severe language and social impairments when returned to society.)
My own experience: I am currently taking a statistics class, and I am very aware that the mathematics and reasoning involved are quite rudimentary—the prerequisite is just one semester of calculus, and there have been only one or two places where knowledge about, say, integrals has been helpful. It's not as though basic calculus is a very difficult subject anyway, compared to God-knows-what-else that higher level mathematicians study (hyperbolic geometry? Abstract and linear algebra? Combinatorics?). Now, most of the time I do find it easy to understand and use the concepts in statistics, but every once in a while I get stuck on a particular problem or issue. And, at these points, my venomous pride comes into play: knowing that the material is simple, I berate myself all the more for not picking it up easily. I have to wonder though, is this ever helpful? Such self-castigation is counterproductive: I feel more frustrated and upset with myself, which in turn makes it more difficult to focus on the work, which again makes me upset and frustrated — and before you know it, we have a vicious cycle and/or positive feedback loop spiraling out of control.
Now, I began this post by speaking as though it is a bigger hindrance for adults than children (and it no doubt is). But, as it turns out, children are not always free from the detrimental effects of pride either.
Studies by Claudia M. Mueller and Carol S. Dweck indicate that complimenting children on their intelligence can actually have damaging rather than beneficial effects on their self-esteem and willingness to address difficult problems. This happens if the praise emphasizes ability rather than effort put forth.
From their article's abstract:
Contrary to this popular belief, six studies demonstrated that praise for intelligence had more negative consequences for students' achievement motivation than praise for effort. Fifth graders praised for intelligence were found to care more about performance goals relative to learning goals than children praised for effort. After failure, they also displayed less task persistence, less task enjoyment, more low-ability attributions, and worse task performance than children praised for effort. Finally, children praised for intelligence described it as a fixed trait more than children praise for hard work, who believed it to be subject to improvement.
Part of the very real problem is that children (and, of course, adults too) want to feel and look smart, particularly if they have been led to believe that they are smart. Sometimes this will incline a child to favor those activities which are easiest in order to maintain their smart image. After all, surely only ungifted plebians have to actually struggle in order to learn things — not like those brainiacs who breeze through the most abstruse material with the greatest of ease. Here's another quote from article's prepatory discussion:
For example, Dweck and her associates have demonstrated that children who hold performance goals are likely to sacrifice potentially valuable learning opportunities if these opportunities hold the risk of making errors and do not ensure immediate good performance (Elliott & Dweck, 1988). That is, "being challenged" and "learning a lot" are rejected in favor of "seeming smart" by children who subscribe to a performance orientation (Mueller & Dweck, 1997).
In other words, children who are overly focused on doing well (rather than trying hard) are reluctant to try new things, particularly if failure might compromise their image as "intelligent." Unfortunately, opening oneself to the possibility of failure is a very necessary part of trying any new activity: closing oneself off from potentially valuable but unfamiliar experiences may wind up stunting one's intellectual growth. (I plan to write more on this subject in the near future.)
Another fascinating point that Mueller and Dweck bring up is how the way children are praised can affect how they conceptualize intelligence. Children praised for their good performance (rather than their hard work) tend to see intelligence as a fixed, static trait rather than something which can be developed and improved. Something along the lines of, "either you're born with it or you ain't" — which seems to be an unfortunately all-too-common view for the average person. Failure and success are then seen in the light of ability rather than effort.
Society really doesn't help with this. We venerate the myth of genius, the prodigy, the wonder-child who's "always right" through some innate, Nature-given powers. However, I think the reality is that these cases (if they can even be said to exist) are very, very, very rare. So rare, in fact, that I strongly suspect that the vast majority of people who are thought of as "geniuses" really did not possess much more in the way of "raw brainpower" or "talent" than the average person. Thomas Edison said, "Success is 10% inspiration and 90% perspiration" — and if you don't believe a prolific inventor of his caliber, who can you believe? Vincent van Gogh worked like a fanatic at honing his painting skills: he may have been talented to begin with, but his brilliance may have been moreover due to his hard work and perseverance. If one examines Albert Einstein and Isaac Newton's lives, one does not necessarily find early displays of talent so much as early displays of intense, self-motivated interest in understanding the world.
To return to my own problems with my statistics course: clearly it does not benefit me to get worked up over my own failings. High standards can be very helpful at times as something to aim towards, but I do not see any compelling reason to allow rampant self-flagellation in the process. The key is to dedicate energy and thought toward growth; be aware when you fall short of your target, but why be cruel to yourself if you don't meet it? Does needless criticism help you to grow more? I doubt it. When I worry that I am dense for not comprehending a subject easily, I am distracting myself from what is really important — namely, that I engage the material, attempt to absorb it with an open mind, and enjoy the experience.
The same ought to apply for children: maintain high expectations, but only if you can present these expectations in a friendly, encouraging manner. Teach them to enjoy struggling — putting forth effort — rather than gold stars and A+'s. Teach them not to fret so much about intellectual pride.