I think in the early '90s, you coined the term "desirable difficulties." Now these
are obviously not the sort of things that would occur to the students who would immediately
think of them when studying for an exam or something. Could you just explain desirable difficulties?
Well, the notion of desirable difficulties is that it refers to a set of manipulations
that all have the property that they create challenges, a sense of difficulty, during
the acquisition process. That's the sense in which they are difficulties. They're
desirable in the sense that they enhance long-term retention and transfer. So therein the conditions
of learning or practice examples, rather than keeping them constant and predictable, reducing
using tests rather than presentations as learning, interleaving the separate things to be learned
rather than blocking practice on each at a time—there's a whole set of these that
create this misimpression. Actually, I've just given you the desirable difficulties.
They create the sense of difficulty but then are associated with better long-term retention.
Really, another way to put all this is a very old distinction going back to the 1930s between
performance and learning. Performance would be like how accurate you are, how rapidly
you can do something during the acquisition process. Learning is those changes, and relatively
permanent changes, that will support your being able to recall and use this information later.
That's what we would like to optimize.
But what happens is we can confuse performance during the process as evidence of learning.
Many things that make performance go up very rapidly—massed practice, continuous feedback,
keeping conditions constant and predictable—make performance go up really rapidly and then
are associated with very poor long-term learning.
The other thing that's made these results so important is various things where you ask
people, "What helped you learn better: this condition or that condition," or, "Predict
how well you'll do on a test that comes in a week." It shows that people are really
fooled by their current performance. It's not only an unreliable indicator of whether
learnings happen. It's sometimes exactly the opposite of that.
We're really at risk of misinterpreting whether we've acquired the skills and knowledge
that we are intending to acquire. On one hand, it's never been more important to know how
to learn because more learnings happen outside of formal supervision: we're on our own;
we're at a computer; we're doing this; we want to learn some new tech feat for job
purposes or whatever, across a whole lifetime. We need to know how to learn, but it's not
easy. Our intuitions mislead us. A lot of the standard practices that we've been exposed
to in schooling are not optimal. We would just—natural for us to think, "Well, if
our teachers did that, that's the way we should do it," and that's often wrong.
It's really a critical kind of juncture of: can people learn how to manage their—be
effective stewards of their own learning? And that's the ultimate sort of survival skill.
My name is Bob. I think about learning.