Scribner, S. (1983) Mind in action: A functional approach to thinking. In M. Cole, Y. Engestrom. And O. Vasquez (Eds.) Mind, Culture and Activity: Seminal papers from the Laboratory of Comparative Human Cognition, (pp. 354-368). NY, NY: Cambridge University Press.
This "classic" and widely cited article is about the use of mathematics
knowledge by dairy workers who assemble and price orders
and take inventory in the warehouse.
The first thing we learned from our systematic observations is that
the preloaders had a large repertoire of solution strategies for what
looked like the "same problem."
We postulated a "law of mental effort": "In product assembly, mental work
will be expended to save physical work."
By comparing various modes of solution
in terms of the number of moves they required, we could determine
which strategy represented a "least-physical-effort solution" under a
given set of circumstances. We refer to these as optimal solutions.
Pricing delivery tickets is all symbolic work. Speed and accuracy count.
A problem by problem analysis of solution strategies showed that the
case price technique functioned as an effort saver in a manner analogous
to the nonliteral optimal solutions in the product assembly task - with
an important difference. The effort saved here was mental, not physical,
Use of case price either eliminated computation altogether or simplified
Practice makes for difference - the problem-solving process is restructured by the knowledge
and strategy repertoire available to the expert in comparison to the
One feature of skilled problem-solving is the dependency of problem solving
strategies on knowledge about the workplace. Skill in the dairy was not
Variability was an outstanding feature of skilled performance on all
Skilled practical thinking at work is goal-directed
and varies adaptively with the changing properties of problems and
changing conditions in the task environment.
contrast to the conventional psychological model of learning which assumes a progression from the particular and concrete to the general
and abstract, skill acquisition at work seems to move in the direction of
mastery of the concrete.
Work activities have certain peculiarities and cannot be considered
representative of all practical thinking in action.
At the end of one interview, a seasoned delivery driver described to
me the public's image of a milkman. He said , "Most people believe you
only need a strong back to be a milk man. But, come to think of it, there
is a lot of brain work involved." I think he is right.