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Approved For Release 2000/08/08
: CIA-RDP96-00789R002200410001-2
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Final Report— Objective
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December 1986
Covering the Period 31 July 1987 to 30 September 1988
META-ANALYSIS OF FORCED-CHOICE
PRECOGNITION EXPERIMENTS
By:
EDWIN C. MAY
SRI International
CHARLES HONORTON
DIANE B. FERRARI
GEORGE HANSEN
-
Psychophysical Research Laboratories
Prepared for:
Peter J. McNelis, DSW
CONTRACTING OFFICER'S TECHNICAL REPRESENTATIVE
CONTRACT
DAMD1 7-85-C-51 30
SRI Project 1291
Approved by:
MURRAY J. BARON, Director
Geoscience and Engineering Center
333 Ravenswood Ave.
•
Menlo Park, CA 94025
For Releak'l
W^9fiS)S^2^4Wo01 -2
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I INTRODUCTION
We have subcontracted to Psychophysical Research Laboratories (PRL)
to conduct
a
meta-analysis of the forced-choice precognition literature.
Mr. Honorton, the director, has met
the requirements of the subcontract.
Attached,
is the deliverable from PRL.
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Experiments
CHARLES HONORTON
DIANE BAILEYFERRARI
GEORGE HANSEN
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Approved For Release 2000/08/08
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TABLE OF CONTENTS
ABSTRACT
OBJECTIVES
DELINEATING THE DOMAIN
Source of Studies
Criteria for Inclusion
Outcome Measures
General Characteristics of the Domain
OVERALL CUMULATION
Replication across Investigators
The Filedrawer Problem
OUTLIER ELIMINATION
STUDY QUALITY
Study Quality Criteria
Study Quality Analysis
Quality Extremes
Quality Variation in Publication Sources
Study Quality in relation to Year of Publication
“REAL-TIME” ALTERNATIVES TO PRECOGNITION
Method of Determining RNT Entry Point
Use of Mangan’s Method
MODERATING VARIABLES
Selected versus Unselected Subjects
Individual versus Group Testing
Feedback
Time Interval
Influence of Moderating Variables in Combination
DISCUSSION
REFERENCES
CHRONOLOGICAL LISTING OF STUDY REFERENCES
.... 30
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Approved For Release 2000/08/08
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ABSTRACT
We report a meta-analysis of forced-choice precognition experiments published in
English-language parapsychology journals between 1935 and 1987. These studies involve
attempts by subjects to predict the identity or order of target stimuli selected randomly over
intervals ranging from several hundred milliseconds to one year following the subject’s
responses. The database includes 309 studies reported by 62 senior authors. Nearly 2 million
individual trials were contributed by more than 50,000 subjects. Study outcomes are assessed
in terms of overall level of statistical significance and effect size.
We find a small, but consistent, and highly significant overall tendency for directional
hitting (z = 12.14). Analysis based on investigators’ predictions ofconditions associated with
hitting and missing yields a much stronger result (z = 24.23). Thirty percent of the studies
(and 39% of the investigators) have directional outcomes that are significant at the 5%
significance level. Assessment of the vulnerability of this database to selective reporting of
positive results indicates that a ratio of 50 unreported studies averaging null results would be
required for each reported study in order to reduce the overall significance of the observed
outcomes to nonsignificance.
No systematic relationship exists between study outcomes and eight indices of research
quality. Magnitude of effect has remained essentially constant over the survey period, while
research quality has improved substantially.
Four moderating variables appear to covary significantly with study outcome:
• Studies using subjects selected on the basis ofprior testing performance
show significantly larger effects than studies involving unselected sub-
jects.
• Subjects tested individually by an experimenter show significantly larger
effects than those tested in groups.
• Studies in which subjects are given trial-by-trial or run-score feedback
have significantly larger effects than those with limited or no subject
feedback.
• Studies with brief intervals between subjects’ responses and target
generation show significantly stronger effects than studies involving
longer intervals.
The combined impact of these moderating variables appears to be very strong. A nearly
perfect replication rate is observed in the subset of studies using selected subjects, who are
tested individually and receive trial-by-trial feedback.
Psychophysical Research Laboratories
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