Page 229 - Deep Learning

212 Adaptation

The dissociation between action and judgment is well supported by
everyday experience. For example, an athletic coach is not necessarily a world
champion; a good editor is not necessarily a successful author; and so on. The
ability to judge a performance or a product benefits from some level of skill
in the relevant domain but does not require superior performance. On the
other side of the coin, superior performance is not necessarily accompanied
by connoisseurship. An artist or an inventor may or may not be able to recog-
nize genius in others. The dissociation between action and judgment is also
15
supported by different types of experimental evidence. For example, young
children can accurately judge the performance of someone else on numeric
tasks as either correct or incorrect, even though they might be unable to pro-
duce the correct performance themselves. There is neuroscience evidence for
specific brain areas that deal with internal conflicts, error detection and error
correction. 16
In short, a person might possess the declarative knowledge required to
judge a performance as inappropriate, incorrect or unhelpful, but nevertheless
lack the practical knowledge required to perform better. This is not an exotic
possibility but the normal case. The distinction between practical and declara-
tive knowledge resolves the paradox that people can detect their own errors
but it raises the question of how declarative knowledge can be represented in
memory so as to serve this evaluative function.

Error Signals as Constraint Violations
If the function of declarative knowledge is to support judgment, then it is
helpful to conceptualize the smallest unit of declarative knowledge as a con-
straint rather than a proposition. A constraint is not an assertion about the
world but a prescription. It states what ought to be the case rather than what
is the case. The set of all constraints that apply in a particular task environ-
ment – the constraint base – defines what is meant by a correct performance
in that environment. A task performance that does not violate any of the
constraints in the relevant constraint base is appropriate or correct. Errors –
conflicts between expected and observed outcomes – appear as constraint
violations. For example, the set of all traffic laws is the constraint base for the
traffic environment. A speed limit is a constraint on a driver’s performance,
as is the rule to drive on the right-hand side of the road. The traffic laws do
not specify how people in fact drive; they specify how they ought to drive. A
driving performance that does not violate any of the traffic laws is correct in
the sense of being legal.