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4.3 Schemas keep the complexity of problem solving in check
The discovery that the major difference between people who differed in ability was in terms
of what they held in long-term memory changed our view of cognition. [. . . ] Long-term
memory was not just used by humans to reminisce about the past but, rather, was a central
component of problem solving and thought. (Sweller, 2010a, p. 32)
4.3.1 Scripts and problem-solving schemas tell us what to do
The literature discusses various more specific types of schemas. An often-cited construct is the script or
event schema formulated by Schank and Abelson (1977). Scripts are schemas that encode knowledge of
recurring events and their stereotypical stages and other properties, and allow us to act comfortably and
efficiently in familiar situations. The event of a visit to a restaurant, which consists of typical stages like
ordering, eating, and paying, is a classic example. Similarly, a problem-solving schema tells us what to do
to accomplish a goal in a particular kind of situation. Sweller and Chandler provide a good example:
Someone who is competent at algebra will have a schema for multiplying out a denominator.
The schema will tell that person which of the infinite variety of algebraic equations is amenable
to multiplying out a denominator and the procedure for doing so. When faced with a problem
such as a/b = c, solve for a, we can immediately solve such a problem, despite the many
forms in which it could be presented, because our schema for this type of algebra problem
informs us, for example, that the solution requires multiplying out the denominator on the
left-hand side, irrespective of the complexity of the term on the right-hand side. Schemas,
stored in long-term memory, permit us to ignore the variety that would otherwise overwhelm
our working memory. (Sweller and Chandler, 1994, p. 187)
Schemas allow us to draw on our prior experience and general knowledge so as not to be overwhelmed by
the details of what we are currently experiencing. When we see an unfamiliar person – a specific instance of
a familiar, automated schema – we can easily tell that the person is a human and act accordingly, without
having to store or process every tiny detail of the person that our senses barrage us with. Schemas are
crucial to our success in whatever we do as they “allow us to carry out everyday activities with minimum
effort and to capitalize on the regularities of events and situations” (Preece et al., 1994, p. 128).
When faced with a complex problem to solve, we need to process various aspects of the problem and
its solution in working memory simultaneously. A problem-solving schema such as the algebra schema
described above allows us to ignore the specific details of the problem and recognize a more general
pattern for which we have a schema. When a schema is available, it allows the entire problem or a part
of the problem to be dealt with as a single chunk (see Section 4.1 above). In relation to one of their
experimental studies, Sweller and Chandler (1994) discuss the solving of a simple problem: marking a
point with given coordinates in a two-dimensional graphical coordinate system. They argue that for a
complete novice, solving this problem requires an understanding of roughly seven distinct items, e.g.,
the fact that x in P(x, y) refers to a location x on the x-axis. Where the complete beginner may be
overwhelmed, someone who has experience with such problems can incorporate the entire problem into a
single chunk that does not burden working memory greatly – or at all, if automated through practice.
4.3.2 Schemas are a key ingredient of expertise
Educational psychologists have long sought to understand the nature and development of expertise. On
the one hand, the goal has been to characterize the mental representations that experts have and the
ways in which experts put their knowledge to use when solving problems. On the other hand, researchers
have investigated the mental representations and associated processes of novices, and contrasted them
with those of experts. Through such comparisons, it is argued, we may better understand the changes
that take place as we learn, and thereby improve teaching and learning.
An easy explanation for the superior performance of experts in problem solving would be in their
superior ‘cognitive hardware’ such as a larger short-term working memory or superior intelligence. Early
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