Page 218 - Deep Learning

The Growth of Competence 201

The fact that there are multiple theories and models of skill acquisition
should not fool us into conducting experiments with the purpose of selecting
one of them as the better theory. Competitive comparisons of goodness of
fit to experimental data are only meaningful when two hypotheses are mutu-
ally incompatible in the strong sense that if one is true the other cannot be.
But this condition does not hold for hypotheses about individual skill acquisi-
tion mechanisms because nothing prevents human beings from learning in
multiple ways. The theoretical task is not to pit different learning mechanisms
against each other in a race to account for this or that phenomenon, but to
assemble a repertoire of mechanisms such that we can explain as many aspects
of skill acquisition and skill adaptation as possible.
Human beings are efficient learners, and reliance on a protracted period of
learning is a species-characteristic trait, so it is plausible that we have evolved to
be maximally efficient learners. As our eyes are maximally efficient in the sense
that the retina can react to a single photon, so our ability to learn might have
evolved to make use of every bit of information. to be maximally efficient
66
is to make maximal use of all information that might be available to a learner
during practice. This Principle of Maximally Efficient Learning is an example of
what cognitive scientists call a rationality principle. it is an idealization, but
67
it is close enough to the truth to anchor the search for an empirically adequate
theory. The implication is that to propose a theory of skill acquisition is to
assemble a repertoire of nine different learning mechanisms to make use of the
nine types of information.
The pool of hypotheses proposed and formalized in simulation mod-
els already contains one or more well-specified mechanisms to make use
of each of the nine information types. The surprising conclusion is that we
already possess a first-approximation, multimechanism theory of skill acquisi-
tion. More precisely, we possess a family of such theories in which the mem-
bers vary slightly, depending on exactly which variant of each mechanism we
select from the smorgasbord of proposals. Abstracting over those details for
a moment, the nine Modes Theory claims that people acquire skills through
nine different learning mechanisms: (a) Proceduralization, or translating ver-
bal instructions into executable practical knowledge, perhaps in the form of a
set of production rules. (b) Practical reasoning, or reasoning from prior declar-
ative knowledge about the task environment to a conclusion about what to do.
(c) Analogy, or mapping the current task onto an analogical task in memory
and using the strategy for the analogue as a template for the strategy-to-be-
learned. (d) Internalization of demonstrations or solved examples. (e) Caching
outcomes of unselective search (trial and error). (f) Generalization of tentative