Koehler BBS Comm thomsen

From: Phillips Barbara (bp195@psy.soton.ac.uk)
Date: Thu May 21 1998 - 12:17:06 BST


> ABSTRACT: Koehler's summary and critique of research on the base rate
> fallacy is cogent and persuasive. However, he may have overstated
> the case, and his suggestions for future research may be overly
> restrictive. While we agree that methodological approaches to this
> topic should be broadened, we argue that experimental laboratory
> research and the Bayesian normative standard are useful and should
> not be abandoned.

Did Koehler say that experimental laboratory research should be

> In fact, past research has identified a number of factors that
> influence the extent of base rate use. This is not surprising; one
> would be hard pressed to identify any judgmental phenomena that
> operates identically regardless of the context and task parameters.
> Variability in the extent to which a phenomenon occurs does not
> undermine its existence; it merely refines our understanding of when
> and how it happens.

Thomsen is making the point that new findings may simply mean that a
theory needs to be refined; rather than a new theory being developed.

> He suggests that there is little to be gained from further research
> along these lines, and urges researchers to abandon this approach in
> favor of more ecologically valid research examining the use of base
> rates in more realistic decision contexts. However, the fact that
> most research on the base rate fallacy up to this point has been
> experimental laboratory research does not imply that the pendulum
> should now swing to the opposite, correlational field research,
> extreme.

Perhaps Koehler is not saying that experimental research should be
abandoned altogether - just that further research should take a more
ecological approach. This makes sense as ecological studies should be
far more indicative of how people behave in real life. Results of
ecological studies may reveal that reliance on base rates differs
greatly according to the two methods. If this is the case, a detailed
consideration of why this occurs will be necessary in order to improve
our understanding of this area.

> there is no logical necessity that experimental laboratory research
> employ tasks and situations that are low in ecological validity. It
> is not at all difficult to imagine experimental laboratory research
> that incorporates most of the features Koehler exhorts researchers
> to employ: complex and ecologically valid judgment tasks, an
> examination of the effects of varying participant motivations on
> judgmental outcomes, comparisons of judgments to a variety of
> standards in addition to the Bayesian one, and so on.

If an experiment could be done which controlled all the variables and
was high in ecological validity, this would solve the problem!

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