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Partmormal Communication / “Error Some Placl/"
container
or
in
another
room,
without
an
agent.
••Precognition”
tests,
introduced somewhat
later
(59). required the subject to m'akc anticipatory
guesses of the card order before the pack was shuffled or otherwise random-
ized.
Rhine introduced the term "ESP” in his
first major repkrt on the Duke
University work in
1 934
(50). He reported
a
total of 85,7?4 card-guessing
trials, carried out with a wide variety of subjects and under a wide range
of
test conditions. The results as a whole were astronomically
significant,
though informal exploratory trials were indiscriminately pooled with those
carried out under more carefully controlled conditions. Tl^ best-controlled
work during this period was the Pearce-Pratt distance seriesj of clairvoyance
tests (58). in which the subject. Pearce, located in one builjling, attempted
to identify the order of the cards as they were handled, but! not viewed, by
Pratt, the experimenter, located in another building. The
litvel of accuracy
obtained in
this series of 1,850
trials was associated with i probability of
As
a
stimulant
to experimental
research,
Rhine’s work had
unprece-
dented influence. For the
first time
a common methodology was adopted
and employed on
a
large
scale by
a number of independent and widely
separated
investigators. For
the
first
time,
also,
the
scientific community
was confronted with a body of data, collected through conventional meth-
ods, which
it could no longer ignore—nor too
hastily
accept. The wide-
scale adoption
of the
card-guessing methodology was accompanied
by
a
plethora of critical
articles, challenging almost every aspect of the evalua-
tive techniques and
the experimental
conditions. During ihe
period
be-
tween
1934 and
1940, approximately 60
critical
articles by 40 authors ap-
peared,
primarily
in
the
psychological
literature. While
cjird-guessing
is
no longer the primary methodology
in experimental
parapjsychology,
the
questions which
arose
over
its
use
are
of equal
relevant
to
the more
sophisticated approaches used today.
!
The first major issue [concerned the
validity of the assumption that the
probability of success in the\ card-guessing
experiments uw actually 1/5.
If chance expectation
is other than
1/5, the significance ot the observed
deviations would obviously be
in doubt. This
issue was qujckly resolved
by mathematical
proof and
through
empirical
“cross-check^,”
a form
of
control series in which responses (guesses) were deliberately compared with
target orders
for which they were not intended
(e.g., responses on run
n,
matched with the target sequence for run
«.,). Empirical cross-checks were
reported
for 24
separate experimental
series
involving
a
total
of
12,228
runs (305.700 individual
trials). While the actual experimental run
scores
(e-g- guesses on run
nj compared
to
targets
for run
n,) were highly
sig-
nificant and yielded a mean scoring rate of 7.23/25, the control cross-check
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;
:'-;
v
'
Paranormal Communication /
44Error Some Pic ttV*
It
is clear that at least some of the early exploratory series reported in
Rhine’s monograph were open to criticism for inadequate controls against
sensory cues. While Rhine did not base major conclusions on such poorly
controlled data, inclusion of them in his monograph provided a ready target
for critical reviewers and sidetracked discussion away from the better con-
trolled work, such as the Pearce-Pratt
series, which was not susceptible to
explanation by sensory cues.
Defects in an early commercial printing of ESP cards were reported by
several investigators (18, 25).
It was found that the cards were warped and
could under certain conditions be identified from the back. This discovery
circulated widely for a time as an explanation of all successful
(i.e.,
statis-
tically significant) experimental
series. The parapsychologists retorted
that
defective cards had not been employed in any of the experiments reported
in the literature and that, in any case, they could not account for results
from
studies
involving adequate
screening with
such
devices
as opaque
envelopes, screens, distance, or work involving the precognition paradigm
in which the
target sequences were not generated until
after the subject
had made his responses (53, 54, 72).
By 1940 nearly one million experimental trials had been reported under
conditions which precluded
sensory
leakage. These included
five
studies
in which the target cards were enclosed in opaque sealed envelopes (41, 45,
46, 54, 59), 16 studies employing opaque screens
(7, 8,
11,
19, S3, 34, 35, 38,
41, 42, 44, 45, 46, 59, 71), ten studies involving separation of subjects and
targets in different buildings (50, 51, 52, 53, 34, 32,
8, 77, 61, 60), and two
studies involving precognition tasks (59, 75). These data are summarized in
Table
1. The results were independently significant in 27 of the 33 experi-
ments. By the end of the 1930s there was general agreement that the better-
controlled ESP experiments could not be accounted
for on
the
basis of
sensory leakage.
The hypothesis that significant '‘extrachance" deviations in ESP experi-
ments might be attributable to motivated scoring errors was investigated in
several studies. In one investigation (26), 28 observers recorded 11,125 mock
ESP
trials. Of these, 126
(1.13 percent) were misrecorded. Observers
favor-
able
1: ESP card-guessing experiments (1934-1939) excluding sensory cues*
Method
Studies
N (Trials)
Mean/25
p<
"Clairvoyance" paradigm,
stimuli in sealed, opaque
envelopes
129,775
5.21
4.0 x 10-”
"Clairvoyance" paradigm,
stimuli concealed by opaque
sheens
497,450
5.44
2.0<X lO" 11
Distance6
164,475
5.37
jft-u
Precognition paradigm*
115,330
5.15
2.95 x 10" 4
References given in text.
b Includes work with both telepathy" and "clairvoyance" paradigms
* Stimuli generated after subjects made their responses
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CIA-RDP96-00789R0031 001 20001 -4
Journal of Communication , Winter 1975
able to the ESP hypothesis made
71.5 percent snore errors of commission
(increasing ESP
scores),
while
those who
were!
unfavorable
to
the ESP
hypothesis made
100
percent more
errors
of {omission
(decreasing ESP
scores). Murphy (37) reported an analysis of
1 75,000 trials from experiments
reporting positive evidence
for ESP and found jonly
175 errors
(0.10
per-
cent). Greenwood
(12) reported only 90 recording errors in rechecking his
500,000-trial control study, of which 76 were errors of omission.
Some critics also alleged that improper selection of data could account
for experimental successes. This could be done in several ways:
(a) selection
of subjects: (b) selection of particular blocks of tjata out of larger samples;
(c) selection of one of several forms of analysis; $nd (d) selective reporting
of
particular
studies. The
questions
raised
haye sometimes
been
stated
cynically
in
the
form,
“Parapsychologists
must’ run
100
subjects
before
they find one with
ESP ." As
if in defense agaipst
this charge, a number
of the reported studies specifically stated that all jof the data collected were
included in the analysis (see 43, pp. 118-124, Table
12).
Concerning
selection
of
subjects, Warner
(76) suggested two
criteria:
first,
results
of "poor”
subjects must be included up
to the point when
they are discontinued
since
it does not matter how many
trials a given
subject makes
as long as
all of the
trials
(for
all
subjects) are included;
second, exclude
all preliminary
trials
(for both “good" and
“poor"
sub-
jects) and use preliminary screening studies to select "good" candidates for
formal work. These criteria were generally endorsed by the chief critics of
the period (e.g., 23).
The question of post hoc selection of analyses was not a point of serious
concern in the period between
1934 and 1940, thbugh
it
is relevant to the
assessment
of some
of
the
process-oriented
investigations reported more
recently. The
question
of whether
nonsignificant
studies were withheld
from
publication
involves an
issue which
is of great Concern
to
the
be-
havioral sciences as a whole (70, 81) and one whicii is difficult to accurately
assess since there
is no way of knowing how manjy studies may have been
withheld from
publication
because
their
results {failed
to disconfirm
the
null hypothesis.
Several studies of American Psychological Association publication
poli-
cies (4, 70, 81) indicate that experimental studies
ift general are more likely
to be published
if the null hypothesis
is rejected
at the conventional
.05
and
.01 alpha
levels than
if
it
is not rejected. These studies also indicate
that a negligible proportion of published studies pre replications. Bozarth
and Roberts
(4), in a survey of
1,334
articles from psychological journals,
found that 94 percent of the articles involving statistical tests of significance
reported rejection of specific null hypotheses; only eight articles (less than
1 percent) involved replications of previously published studies.
With respect to the implications of such selection for the ESP hypothesis,
there are two partial answers. First, considering the degree of critical inter-
est which prevailed in the 1930s,
it seems unlikely |that nonsignificant find-
ings would have been repressed during this period; second, the high levels
its
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Paranorrfial Communication / "Error Some Place!"
„
Of significance attached
to some of the reported ESP investigations would
necessitate
postulating astronomical numbers of "chance"
trials
in order
to dilute the overall deviations to chance. To take one example, consider
the Pearcc-Pratt senes of 1,850
trials which yielded p =
IO-22
. As Soal and
Bateman
(f>6) pointed out,
it
is difficult to believe that 10™(ten thousand
million)
sets of
1,850
trials could have possibly been carried out between
1934 and
1940
(or, for that matter, since
1940). But, as Soal and Bateman
suggest,
.
. if we posit this absurd estimate as an upper limit [with overall
chance totals], that would
still give us odds of 10™
.
.
. against the supposi-
tion that the Pearce-Pratt results were a run of pure luck.”
The possibility of obtaining significant "extrachance” results by stopping
an experimental
series at "favorable” points was also raised
(9,
31). While
this
optional stopping" hypothesis was generally agreed to be of significance
only
in
cases
of marginally
significant
results,
it
led
to
the adoption
of
several procedural modifications:
specification of the total number of trials
m advance of data
collection, or accumulation
of data
in
blocks of pre-
determined size.
r
The possibility was raised by several critics that hand-shuffled cards may
display a tendency to stick together or otherwise produce patterns which
could produce spurious results
(24,
82). While the cross-check type of con-
trol
series,
described
earlier,
failed
to reveal any evidence of patterning
there was a general trend away from hand shuffling in the later published
studies, which
utilized
tables of prepared random numbers as a
basis
for
generating target sequences.
There was
and
is
(e.g.,
15)—a rather widespread
belief that most of
the evidence supporting the ESP hypothesis originated
in
the Duke Uni-
versity studies and that most independent replications by other investigators
were nonconfirmatory. A survey of the published
literature between
1934
and 1940 fails to support this claim. Table 2 shows all the published experi-
mental reports during
this period which provided
statistical treatment of
the
data.
Inspection
of
this
table
reveals
that
a majority
(61
percent)
of
the outside
replications report
significant
results
(p <
.01) and
that
the
proportion of significant studies was not significantly greater for the Duke
University group
(x
2 =
1.70,
df).
By 1940, the active methodological
controversy was over .
The issues raised were,
for the most
part, legitimate, and
investigators
modified
their procedures
to safeguard
their
results from methodological
criticism. The major issues raised since 1940 center on alleged anomalies in
probability theory and
the hypothesis of widespread
investigator fraud.
Spencer Brown
(68, 69) has suggested
that
statistically significant card-
guessing studies provide evidence, not of extrasensory modes of communica-
tion, but
of fundamental
defects
in
probability
theory. He makes
three
criticisms
of random number
sequences:
(a)
published random number
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