Date: Sat Nov 20 1993 00:51:00 Subj: Memory Tricks ABDUCT - Diagnoses of Alien Kidnappings

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Date: Sat Nov 20 1993 00:51:00 From: John Powell Subj: Memory Tricks ABDUCT ------------------------------- Diagnoses of Alien Kidnappings That Result From Conjunction Effect by Robyn M. Dawes and Matthew Mulford (The Skeptical Inquirer, Vol. 18, No. 1, Fall 1993, Copyright 1993 by the Committee for the Scientific Investigation of Claims of the Paranormal, 3965 Rensch Road, Buffalo, NY 14228, published quarterly with a membership/subscription rate of $25/yr.) Events and feelings may be better recalled when they occur in combination than singly, to the point that a conjunction of two alleged events or feelings may be iudged to have occurred with greater frequency in one's life than one of them alone. One part of a coniunction can facilitate recall of the conjunction, and hence of another part of the experience - and combinations of events can be judged to be more probable than their components (Tversky and Kahneman 1983). The observer to whom it is reported, however, knows that such a coniunction is necessarily less probable than any one of its components. Thus, the observer may attach special significance to such a conjunction. For example, in supporting a conclusion that post-traumatic stress from kidnapping by aliens is a major mental-health problem in this country (allegedly affecting at least 2 percent of the population), Hopkins and Jacobs (1992) cite the rate of affirmative responses to a recent Roper Poll question: "How often has this happened to you: Waking up paralyzed with a sense of a strange person or presence or something in the room ?" Their rationale for considering affirmative responses particularly diagnostic of alien kidnapping involves the conjunction of the two components in the question: "A fleeting sensation of paralysis is not unusual in either hypnogogic or hypnopompic states, but adding the phrase 'with a sense of a strange person or presence in the room' forcefu11y narrows the scope of the question" (p. 56). As part of a (much) larger study, we asked that same Roper Poll question of 144 subjects (mainly University of Oregon students and some townspeople interested in the $20 pay for two hours). Forty percent answered that this had happened to them at least once. A randomly selected control group of 144 subjects in the same study were asked simply how often they remembered waking up paralyzed. Only 14 percent answered that this had happened to them at least once, (chi-square = 24.26; p < .001, phi = .29). (See Table 1.) The contingency was stronger for women (phi = .44) than for men (phi = .17), significantly so according to a Goodman-Plackett chi-square value of 4.74. Nevertheless it was significant for both sexes (with chi-squares of 25.38 and 4.43, respectively). Thus, due to a conjunction effect in memory, the added phrase "with a sense of a strange person or presence . . . in the room" actually "broadens the scope" of the question, rather than narrowing it. Hopkins and Jacobs are, of course, correct in maintaining that the additional phrase _should_ "narrow the scope." It's just that the phrase doesn't. What they have discovered, therefore, is not evidence of alien kidnappings, but of a common irrationality in the way we recall our lives. References Hopkins, B., and D. M. Jacobs. 1992. "How This Survey Was Designed." In Bigelow Holding Company, _An Analysis of the Data from Three Maior Surveys Conducted by the Roper Organization_, pp. 55-58. Tversky, A., and D. Kahneman. 1983. Extensional versus intuitive reasoning: The conjunction fallacy in probability judgments. _Psychological Review_, 90: 293- 315. --- Robyn M. Dawes is University Professor in the Department of Social and Decision Sciences, Carnegie Mellon University, Pittsburgh, PA 15213-3890. Matthew Mulford is in the Department of Political Science, University of Oregon, Eugene 97403.


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