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Studies in the psychological laboratory 363
inferences from the pattern of the laboratory findings on the quality
of human cognition for understanding failures in strategic cognition.
In Chapter 9, we provided a catalogue of the results of research in
the psychological laboratory and discussed possible implications of
these for probability assessment. In this chapter, our focus is somewhat
different: we exemplify those psychological processes which, in our
view, underpin cognitive inertia.
Studies in the psychological laboratory
As we saw in Chapter 9, research within what became known as the
‘heuristics and biases’ paradigm focused on the rules of thumb that
decision makers can use in making judgments. The overall conclusion
of this research was that the heuristic principles used could lead to
bias. Some authors went as far as to coin the phrase ‘cognitive cripple’
to describe Man’s performance on laboratory, paper-and-pencil tasks. 11
Several aspects of this research link directly to the phenomenon of
strategic inertia as we have described it. In a number of investigations,
Edwards and his colleague 12 found that unaided revision of opinion was
often less than Bayes’ theorem (a normative theory of opinion revision,
see Chapter 8) would prescribe. This result was termed ‘conservatism’.
Most of the laboratories’ research has used the ‘book-bag-and-pokerchip’
paradigm. The basic paradigm was as follows. The experimenter
holds three opaque book bags. Each contains 100 poker chips in different,
but stated, proportions of red and blue. The experimenter chooses one
bag at random, shuffles the poker chips inside and successively draws
a single poker chip from the bag. After each draw, the poker chip is
replaced and all the poker chips are shuffled before the next draw.
The subjects’ task is to say how confident (in probability terms) he
or she is that the chosen bag is Bag 1, Bag 2 or Bag 3. The data from
a large number of laboratory studies, using tasks very similar to the
one described, show that the amount of opinion revision is often less
than the theorem would prescribe. However, theamount of conservatism
shown in a particular task is highly situation specific. Pitz, Downing and
Reinhold 13 documented an ‘inertia effect’, where people tended not to
revise their probabilities downward once the initial part of a sequence
of data had favored one of the hypotheses (bags) under consideration.
In other words, people seem unwilling to reduce their probabilities on
favored hypotheses following disconfirming evidence. Highly diagnostic
data are not recognized as such. Winkler and Murphy 14 argued that