Recent research in cognitive
psychology shows that people consistently make mistakes on simple everyday
tasks, even when the subjects
are knowledgeable, intelligent people, who undoubtedly possess the necessary
knowledge and skills to perform correctly on those
tasks. The source of these mistakes is often shown to
be the insuppressible influence of intuitive thinking.
This research, the heuristics and biases program, has
been carried out by Kahneman and Tversky and oth-
more recent and, in fact, largely reflecting cultural
evolution). S1 processes are characterized as being
fast, automatic, effortless, unconscious, and inflexible
(difficult to change or overcome). In contrast, S2
processes are slow, conscious, effortful and relatively
flexible. In addition, S2 serves as monitor and critic of
the fast automatic responses of S1, with the “
authority” to override them when necessary. In many situations, S1 and S2 work in concert, but there are
situations (such as the ones concocted in the heuristics and biases research) in which S1 produces quick
automatic non-normative responses, while S2 may or
may not intervene in its role as monitor and critic.
A brief analysis of the bat-and-ball data can
demonstrate the usefulness of dual-process theory for
the interpretation of empirical data. According to this
While people in everyday situations prefer responses over careful
systemic reasoning, students solving mathematical problems would be expected to consciously train
their methodical thinking to check, and override if necessary, their immediate intuitive responses.
From these findings we may understand the strong influence intuition.
ers during the last 30 years, and has led to Kahneman’s receiving the 2002 Nobel Prize in economics. 1
In his Nobel Prize lecture, Kahneman opened with
the following story:
A baseball bat and ball cost together one dollar and
10 cents. The bat costs one dollar more than the ball.
How much does the ball cost?
Almost everyone reports an initial tendency to
answer “ 10 cents” because the sum $1.10 separates
naturally into $1 and 10 cents, and 10 cents is about
the right magnitude. Indeed, many intelligent people
yield to this immediate impulse: 50% (47/93) of
Princeton students and 56% (164/293) of students at
the University of Michigan gave the wrong answer [ 2,
What are our mind’s mechanisms that may
account for these empirical findings? One current
influential model in cognitive psychology is
Dual-Process Theory [ 4, 10, 11]. According to this theory,
our cognition and behavior operate in parallel in two
quite different modes, called System 1 (S1) and System 2 (S2), roughly corresponding to our common
sense notions of intuitive and analytical thinking.
These modes operate in different ways, are activated by different parts of the brain, and have different evolutionary origins (S2 being evolutionarily
1Tversky unfortunately died several years earlier.
theory, we may think of this phenomenon as a “
cognitive illusion” analogous to the famous optical illusions from cognitive psychology. The surface features
of the problem cause S1 to jump immediately with
the answer of 10 cents, since the numbers one dollar
and 10 cents are salient, and since the orders of magnitude are roughly appropriate. The roughly 50% of
students who answer 10 cents simply accept S1’s
response uncritically. For the rest, S1 also jumps
immediately with this answer, but in the next stage,
S2 interferes critically and makes the necessary adjustments to give the correct answer (five cents).
Recently, a similar phenomenon has been found in
advanced mathematical thinking, with college students learning abstract algebra [ 6]. While it seems
natural that people in everyday situations prefer
(however unconsciously) quick approximate
responses that come easily to mind over careful systematic rule-bound reasoning, students solving mathematical problems during a university course would
be expected to consciously train their methodological
thinking to check, and override if necessary, their
immediate intuitive responses. From these findings
we may understand the strong influence intuition,
especially its tendency to be influenced by surface
clues, has on our thinking. In this article we demonstrate that a similar phenomenon—and a similar
explanation—may also hold for OOD tasks carried
out by experts in industry.
A note on terminology: We follow Kahneman and