[Jdm-society] Re: Linda

[Julie Irwin {irwinj}]

oops, two of the smartest people I know seem to think I said that the
conjunction fallacy was the result of conversational norms, so I'm
worried that other such people think this, too.  I tried to be clear in
my "play" that I think that the conjunction fallacy (and other uses of
the representativeness heuristic) are really real and explain a lot of
behavior.  I was just trying to explain disagreements over Linda, who
could inspire lots of other ways of thinking, too.

(Can you believe we're still talking about her, all of these years
later?)

cheers,
Julie

Julie R. Irwin
Marketing Department
McCombs School of Business
University of Texas
Austin, TX  78703 
512-471-5419
512-471-1034 (fax)


-----Original Message-----
From: jdm-society-bounces at mail.sjdm.org
[mailto:jdm-society-bounces at mail.sjdm.org] On Behalf Of Jonathan Baron
Sent: Monday, February 14, 2005 5:37 AM
To: jdm-society at mail.sjdm.org
Subject: Re: [Jdm-society] Re: Linda

Our library has access to PsycInfo, a really useful resource.  I
looked up "conjunction fallacy" or "conjunction effect" and found
the following two abstracts, which seem to me to settle the issue
(as well as research in psychology ever settles anything) of
whether the effect depends entirely on disagreement between
subjects and experimenter on what the question means:

A Different Conjunction Fallacy  
Bonini, Nicolao; Tentori, Katya; Osherson, Daniel 

Source  Mind & Language. Vol 19(2), Apr 2004, pp. 199-210 
  
Abstract Because the conjunction p-and-q implies
p, the value of a bet on p-and-q cannot exceed the value of a bet 
on p at the same stakes. We tested recognition of this principle
in a betting paradigm that (a) discouraged misreading p as
p-and-not-q, and (b) encouraged genuinely conjunctive reading of
p-and-q. Frequent violations were nonetheless observed. The
findings appear to discredit the idea that most people
spontaneously integrate the logic of conjunction into their
assessments of chance. (PsycINFO Database Record (c) 2004 APA,
all rights reserved) (journal abstract )

On the reality of the conjunction fallacy 
Author  Sides, Ashley; Osherson, Daniel; Bonini,
Nicholao; Viale, Riccardo 

Source  Memory & Cognition. Vol 30(2), Mar 2002,
pp. 191-198 
  
Abstract  Attributing higher "probability" to a
sentence of form p-and-q, relative to p, is a reasoning fallacy
only if (1) the word probability carries its modern, technical
meaning and (2) the sentence p is interpreted as a conjunct of
the conjunction p-and-q. Legitimate doubts arise about both
conditions in classic demonstrations of the conjunction
fallacy. We used betting paradigms and unambiguously conjunctive
statements to reduce these sources of ambiguity about conjunctive 
reasoning in a sample of college students. Despite the
precautions, conjunction fallacies were as frequent under betting 
instructions as under standard probability
instructions. (PsycINFO Database Record (c) 2004 APA, all rights
reserved)

Jon
-- 
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page: http://www.sas.upenn.edu/~baron
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