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STANFORD RESEARCH INSTITUTE
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12 March 1974
Progress Report No. 1
Covering the Period 28 January to 1 March 1974
Stanford Research Institute Project 3183
PERCEPTUAL AUGMENTATION TECHNIQUES
-
by
Harold E. Puthoff
Client Private
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I
OBJECTIVE
The purpose of the program is to determine the characteristics of
those perceptual modalities through which individuals obtain information
about their environment, wherein such information is not presented to
any known sense.
The program is divided into two categories of investigation of
approximately equal effort, applied research and basic research.
The
purpose of the applied research effort is to explore experimentally
the potential for applications of perceptual abilities of interest,
with special attention given to accuracy and reliability. The purpose
of the basic research effort is to identify the characteristics of
individuals possessing such abilities, and to identify neurophysiologica
correlates and basic mechanisms involved in such functioning.
II
PROGRESS DURING THE REPORTING PERIOD
A.
Applied Research
1.
Remote Viewing
A number of efforts were begun with respect to obtaining
further information concerning remote viewing phenomena. First, an
experiment has been designed in consultation with SRI psychologists
which will yield precise statistical data as to discrimination ability.
Ten sites known to the subject are to be visited in random sequence by a
target demarcation team. The subject must then make a choice as to
which site is being visited, in addition to providing descriptive material
for content analysis.
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Secondly, a pilot series involving real-time questioning of the
subject by the target team via walkie talkie is being explored to provide
information for designing a protocol to investigate real-time correlations.
One viewing with positive results has been carried out.
Finally, a preliminary remote viewing pilot experiment was
carried out with a subject (H. H. ) previously screened by the EEG correlates
experiment described in our paper submitted for publication (Appendix I).
The target chosen at random was a small red clapboard schoolhouse
structure with a bell steeple on top in a miniature golf course. The
subject's response was that she saw a red clapboard structure with a
steeple that seemed to be artificial as in a movie set. Based on this
result, a series of remote viewing experiments under strict protocols
are planned with this subject.
2.
Detection of Variable Density Target Material
Twenty-seven envelopes were submitted by the sponsor to the
client containing target drawings of variable content and density.
Several hundred sorting trials resulting from six passes per day through
the 27 cards have been carried out, the goal to date being delineation
of the twelve low density target cards from the pencil (6) and blank (9)
cards. The numbered envelopes containing the target material,
sealed and specially secured by the sponsor, are randomized before each
trial and placed inside non-numbered opaque envelopes before being
presented to the subject for sorting. Statistical analysis of the
results and comparison with the key (unknown to the client) will be
carried out after completion of the experimental series.
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B.
Basic Research
1.
Testing Program
During the first month of this program, the Wechsler Adult
SG11
Intelligence Scale (WAIS) instrument was administered by
SG1D
of
to three subjects screened in other
programs as being gifted in the area of paranormal perception. They are
Mr. Patrick H. Price, screened for remote viewing ability, Mrs. Hella Hammid,
screened for EEG correlates to remote stimuli, and Mr. Duane Elgin,
screened for high scoring response to a random target generator. Further
in-depth interviewing of the first two subjects was carried out by
SG11
SG11
SG11
and his colleague,
preparation by
and will be available to the contract
A report is in
SG11
technical representatives when completed.
On the basis of discussion with technical representative,
SRI representatives have consulted with a number of
Bay Area neurophysiologists concerning administration of the Halstead.
Reitan (H-R) Neuropsychology Test Battery. Those contacted include
Dr. Karl Pribram of the Stanford Medical School, Dr. Robert Ornstein
of the Langley-Porter Neuropsychiatric Clinic, and Dr. Donald Lim of
the Veteran's Administration Hospital in Palo Alto. To date satisfactory
arrangements for administration of the H-R instrument have not yet been
made, as only the latter facility has personnel experienced in its
administration, but not ordinarily available for subcontracted consulting.
The three individuals named above have, however, agreed to help locate
an appropriate individual or facility to carry out such testing so no
difficulty is anticipated in meeting this requirement.
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A measure of the visual acuity of one subject (P.P. ) was
obtained utilizing one of the instruments available in the optics
group of the Electronics and Bioengineering Laboratory of SRI. The
measurement method involves forced-choice discrimination on the part of
the subject between alternate zero and finite-contrast grating images,
for each of a number of spatial-frequency gratings. (See Appendix II. )
The system, which is automated, tracks and records the subject's
forced-choice responses to yield a curve of threshold (75% correct choice)
contrast sensitivity as a function of spatial frequency. As might be
expected, higher contrast is required at the low and high frequency
tails of the distribution, as compared with the middle range, to
discriminate between grating and uniform images. The purpose of the
.
test with regard to our program was to determine whether a subject
possessing an unusual ability to view remote stimuli also possessed an
unusual visual acuity response in a threshold-determining instrument,
either because of unusual acuity in the ordinary sense, or through the
use of an extraordinary ability to discriminate between a target and a
blank under conditions of vanishingly-small information content.
The resultant curve lay within the range of expected human
variation indicating no unusual response activity.
2.
Measurement Program
A 10-channel polygraph facility under the direction of
Dr. Jerry Lukas of the Sensory Sciences Research Center has been brought
into the program and certain functions tailored to our specification.
The facility will be used initially to monitor GSR, blood flow
(plethysmograph), and EEG activity of subjects carrying out tasks
involving perception of remote stimuli. For our purposes, the display
of raw data has been augmented by a computer program which has been
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written and debugged to provide on-line 5-second averages of EEG activity
in the theta, alpha, and beta bands. Discussions are now in progress
on experimental protocols to be employed in the utilization of this
facility.
.
EEG data taken prior to this program, but unanalyzed, has been
subjected to analysis in an effort to determine whether a particular
protocol was a viable instrument for defining correlates of remote
perception. The description of the experiment and the results of the
analysis is given in the EEG section of a paper submitted for publication
to Nature, given here as Appendix I.
In an effort to determine the effects of motivation on
paranormal functioning, the following test procedure has been initiated.
One subject (P.P.) has completed 7075 trials on guessing the state of a
four-stage electronic random target generator without monetary reward
being associated with the scoring, and is now repeating the series wit!
a monetary reward scaled to scoring. Upon completion of the series,
the results will be analyzed to determine whether the difference betwe :1
scoring under the two conditions is significant. The reward system,
shown in Table 1, is scaled linearly with difficulty.
Table 1
REWARD SYSTEM FOR SCORING ON 25-TRIAL RUN, P=1/4 PER TRIAL
Nr. hits/25-trial run, N
Prob. of at least N hits
Reward
10
0.071
$ 1
11
0.030
2
12
0.010
5
13
0.0034
12
14
0.00092
35
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INFORMATION TRANSMISSION UNDER CONDITIONS OF SENSORY SHIELDING
Russell Targ
Harold Puthoff
Electronics and Bioengineering Laboratory
Stanford Research Institute
Menlo Park, California
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FIGURE CAPTIONS
1. Target pictures and responses drawn by Uri Geller under shielded
conditions.
2. Computer drawings and responses drawn by Uri Geller.
a. Computer drawing stored on video display
b. Computer drawing stored in computer memory only
c. Computer drawing stored on video display with zero intensity
3. Occipital EEG spectra, 0 to 20 Hz, for one subject (H.H. ) acting as
receiver, showing amplitude changes in the 9 - 11 Hz band as a
function of strobe frequency.
Three cases: 0, 6, and 16 flashes per
second (12 trial averages) .
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INTRODUCTION
In this paper we present results of experiments suggesting the
existence of one or more perceptual modalities through which individuals
obtain information about their environment, wherein this information is
not presented to any known sense.
Such perceptual abilities are often
considered to be paranormal. The literature in the field"
1-3
coupled with
our own observations have led us to conclude that such abilities can be
studied under laboratory conditions.
The phenomena we have investigated most extensively pertain to the
ability of certain individuals to describe graphical material or remote
scenes shielded against ordinary perception. In addition, we also performed
pilot studies to determine if electroencephalographic (EEG) recordings
might indicate perception of remote happenings even in the absence of
correct overt responses.
. In these experiments we concentrated on what we considered to be our
primary responsibility -- namely, to resolve under conditions as unambiguous
as possible the basic issue of whether a certain class of paranormal
perception phenomena exists. Therefore, we conducted our experiments with
sufficient control, utilizing visual, acoustic, and electrical shielding,
to ensure that all conventional paths of sensory input were blocked. At
all times we were vigilant in the design of our experiments to take
measures to prevent sensory leakage and to prevent deception, whether
intentional or unintentional, on the part of our subjects.
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The overall goal of our research program is the determination of the
laws underlying these phenomena. That is, our goal is not just to catalog
interesting events, but rather to uncover patterns of cause-effect rela-
tionships that lend themselves to analysis and hypothesis in the forms
with which we are familiar in scientific study. The results presented
here constitute a first step toward that goal, in that we have established
under known conditions a data base from which departures as a function of
physical and psychological variables can be studied in future work.
In this paper we describe three related experiments which we consider
to represent a single ability exhibiting different rates of information
transmission. First, we conducted experiments with Mr. Uri Geller in
which we examined his ability, while located in an electrically shielded
room, to reproduce target pictures drawn by experimenters located at remo
locations. Second, we conducted double-blind experiments with two
individuals, Mr. Ingo Swann and Mr. Pat Price, in which we measured their
ability to describe remote outdoor scenes many miles from their physical
location. Finally, we conducted preliminary tests using electroencephalo-
grams (EEG), in which subjects were asked to perceive whether a remote
light was flashing, and to determine whether a subject could perceive the
presence of the light, even if only at a noncognitive level of awareness.
REMOTE PERCEPTION OF GRAPHIC MATERIAL
We describe here a series of experiments in paranormal perception
with a 27 year old Israeli subject, Uri Geller. In preliminary testing
Mr. Geller apparently demonstrated an ability to reproduce simple pictures
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(line drawings) which had been drawn and placed in opaque sealed envelopes
which Mr. Geller was not permitted to handle. However, since each of
the targets was known to at least one experimenter in the room with
Mr. Geller, it was not possible on the basis of the preliminary testing
to discriminate between Mr. Geller's direct perception of envelope contents
and perception via some mechanism involving the experimenters, whether
paranormal or subliminal.
Therefore, an experimental study was undertaken to examine the
phenomenon under conditions specifically designed to eliminate all
conventional information channels, overt or subliminal. This was accomplished
by separating Mr. Geller from both the target material and anyone knowledgeable
of the target material, as in the recent experiments by Musso and Granero.
4
The first part of the study consisted of a series of thirteen separate
drawing experiments carried out over a seven day period. The thirteen-
experiment data set constitutes the entire set of consecutive experiments
.
carried out in the time available for the study, with no experiments deleted.
.
The protocol for the experiments was as follows: At the beginning
of the experiment either Mr. Geller or the experimenters entered a shielded
room so that from that time forward Mr. Geller was at all times visually,
acoustically, and electrically shielded from personnel and material at the
target location. Only following Mr. Geller's isolation from the experimenters
was a target chosen and drawn, a procedure designed to eliminate pre-
experiment cueing. The method of target selection involved random
procedures, such as randomly opening a dictionary and selecting the first
word describing an object that could reasonably be drawn. Furthermore,
.
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in order to eliminate the possibility of pre-experiment target forcing,
Mr. Geller was kept ignorant as to the identity of the person selecting
the target and as to the method of target selection. Mr. Geller's task
was then to reproduce with pen on paper the line drawing being generated
by the experimenters at the target location.
Following a period of effort
ranging from a few minutes to half an hour, Mr. Geller either passed
(when he did not feel confident) or indicated he was ready to submit a
drawing to the experimenters, in which case the drawing was collected
before Mr. Geller was permitted to see the target.
In order to prevent sensory cueing of the target information,
Experiments 1 through 10 were carried out using a shielded room in SRI's
facility for EEG research.
The degree of acoustic and visual isolation
provided for this experiment is that afforded by a double-walled steel
room, locked by means of an inner and outer door, each of which is secure .
with a refrigerator-type: locking mechanism. The person inside the room
is continuously monitored by means of a one-way audio monitor.
The
target picture was never discussed by the experimenters after the picture
was drawn or brought near the shielded room. In our detailed examination
of the shielded room and the protocol used in these experiments, no sensory
leakage has been found.
The conditions and results for the ten experiments carried out in the
shielded room are displayed in Table 1. As indicated in the Table, all
experiments, except Experiments 4 and 5, were conducted with Mr. Geller
closeted inside the shielded room.
In Experiments 4 and 5, the procedure
was reversed -- i.e., the target was located inside the shielded room, with
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Experiment
Date
Geller Location
Target Location
Target
Figure
Shielded room
#1ª
Adjacent room (4.1 m) º
Firecracker
la
2
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Shielded room
#1
Adjacent room (4.1 m)
Grapes
1b
3
8/5/73
Shielded room #1
Office (475 m)
Devil
1c
4
8/5/73
Room adjacent to
shielded room #1
Shielded room #1
(3.2 m)
Solar system
1d
5
8/6/73
Room adjacent to
shielded room #1
Shielded room #1
(3.2 m)
Rabbit
No drawin
6
8/7/73
Shielded room
#1
Adjacent room (4.1 m)
Tree
No drawing
7
8/7/73
Shielded room #1
Adjacent room (4.1 m)
Envelope
No drawing
5
8
8/8/73
Shielded room
#1
Remote room (6.75 m)
Came 1
le
9
8/8/73
Shielded room #1
Adjacent room (4.1 m)
Bridge
1f
10
8/8/73
Shielded room
#1
Adjacent room (4.1 m)
Seagull
1g
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Shielded room
#2℃
Computer (54 m)
Kite (computer CRT)
2a
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Shielded room #2
Computer (54 m)
Church (computer
memory)
2b
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Shielded room #2
Computer (54 m)
Arrow through heart
(computer CRT, zero
intensity)
2c
a
EEG Facility shielded room (see text).
b
Perceiver-target distances measured in meters.
SRI Radio Systems Laboratory shielded room (see text).
TABLE 1. SUMMARY: REMOTE PERCEPTION OF GRAPHIC MATERIAL
1
8/4/73
a
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Mr. Geller on the outside in an adjacent room.
For those experiments in
which Mr. Geller was inside the shielded room, the target location was
in an adjacent room at a distance of about 4 meters, except for Experiments
3 and 8, in which the target locations were, respectively, an office at
a distance of 475 meters and a room down the hall at a distance of about
7 meters.
In Experiment 1, the object drawn on the basis of random dictionary
selection was a firecracker, shown in Fig. 1(a). Mr. Geller's immediate
verbal response via the audio monitor was that he saw "a cylinder with
noise coming out of it."
He made two responses to the target, also shown
in Fig. 1 (a).
In Experiment 2, the target -- also chosen by random dictionary selecti ....--
was a cluster of grapes. Mr. Geller said that he was quite certain that
he had the picture.
1
Both the target picture and Mr. Geller's response
have 24 grapes in the cluster (Fig. 1(b)).
In Experiment 3, Mr. Geller was locked in the shielded room with one
experimenter outside as a monitor while the target was drawn in another
building 475 meters away. The target, again randomly selected from the
dictionary, was a devil (Fig. 1(c)). Mr. Geller spent 30 minutes on his
drawing and expressed. considerable difficulty in getting the target. The
results are interesting from the standpoint of possible insight into the
process that they provide. His drawings consisted of representations of
Biblical symbology, including the "Moses tablets," an apple with a worm,
a snake, and a concluding composite picture with the tablets on top of
the world and the trident outside.
Of these only the trident corresponds
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(c)
01
DEVIL
TARGET
RESPONSE 1
0
0-0
DEN
RESPONSE 2
TARGET
RESPONSE
TARGET
RESPONSE 1
RESPONSE 2
RESPONSE 32
(a)
(b)
7
Sun
S . a. S
TARGET
1
TARGET
2
TARGET
1
-
TARGET
RESPONSE
RESPONSE
RESPONSE
RESPONSE
(d)
(e)
(f)
(g)
FIGURE 1
GRAPHICAL MATERIAL CONSISTING OF TARGET PICTURES AND RESPONSES DRAWN BY URI GELLER
UNDER SHIELDED CONDITIONS
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BRIDGE

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directly to an element in the target drawing.
One is led to speculate that
the Biblical elements in these three drawings are perhaps associational
material triggered by the target.
The target picture for Experiment 4 was drawn by an experimenter
while he was inside the shielded room, with Mr. Geller outside the room
with another experimenter.
In this case the target (Fig. 1(d)) was a
representation of the solar system.
Mr. Geller's response to the target
while outside the room coincides quite well with the target drawing.
In Experiment 5, the person-to-person link was eliminated by arranging
for a scientist outside the usual experimental group to draw a picture,
lock it in the shielded room before Mr. Geller's arrival at SRI, and
leave the area.
Mr. Geller was then led by the experimenters to the
shielded room and asked to draw the picture inside the room.
He said tha
he got no clear impression and therefore did not submit a drawing.
The
elimination of the person-to-person link was examined further in the
second series of experiments with this subject, which is described later.
Experiments 6 and 7 were carried out while we recorded Mr. Geller's
EEG during his efforts to perceive the target pictures.
The target pictures
were, respectively, a tree and an envelope.
He found it difficult to hold
adequately still for good EEG records, said that the experienced difficulty
in getting impressions of the targets, and again submitted no drawings.
For Experiment 8, the target picture was a camel and Mr. Geller's
response was a horse (Fig. 1 (e) ).
In Experiment 9, the target was a bridge.
Mr. Geller's drawing bears some resemblance to the target (Fig. 1(f)), but
before seeing the target picture he stated that he did not know what the
picture was.
8
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At the beginning of Experiment 10, Mr. Geller expressed extreme
confidence and entered the shielded room. The target then chosen for
Experiment 10 was a bird in flight.
Mr. Geller said
almost immediately,
via the audio monitor in the shielded room, that he saw a swan flying over
a hill and that he was sure that his drawing was .correct (Fig. 1 (g)).
Experiments 11 through 13 were carried out in SRI's Engineering
Building, to make use of the computer facilities available there.
For
these experiments, Mr. Geller was secured in a double-walled, copper-screen
Faraday cage 54 meters down the hall and around the corner from the
computer room.
十
For Experiment 11, a picture of a kite was drawn by one of the
experimenters on the face of a cathode ray tube display screen, driven
by the computer's graphics program.
Mr. Geller's response, shown in
Fig. 2(a), was a square with diagonals.
For Experiment 12, a picture of a church was drawn and stored in the
memory of the computer. Mr. Geller's responses are shown in the drawings
of Fig. 2(b). Although his responses have some elements in common with
the target drawing, he did not recognize the target as a church.
In Experiment 13, the target drawing, an arrow
through a heart (Fig. 2(c)),
was drawn on the face of the cathode ray tube and
then the display intensity
was turned off so that no picture was visible. Mr. Geller immediately
The Faraday cage provides 120 dB attenuation for plane wave radio frequency
radiation over a range of 15 KHz to 1 GHz.
For magnetic fields the attenuation
is 68 dB at 15 KHz and decreases to 3 dB at 60 Hz.
.
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-
......
aocao
TARGET
TARGET
1
TARGET
RESPONSE 1
10
RESPONSE 1
RESPONSE
RESPONSE 2
RESPONSE 2
(a)
(b)
(c)
FIGURE 2
GRAPHICAL MATERIAL FROM COMPUTER DRAWING EXPERIMENTS WITH URI GELLER. (a) PICTURE
STORED ON VIDEO DISPLAY. (b) PICTURE STORED IN COMPUTER MEMORY ONLY. (c) PICTURE
STORED ON VIDEO DISPLAY WITH ZERO INTENSITY.
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drew an arrow under a rectangle and then drew another arrow inside a suit-
case, which he considered a better representation of the target.
To obtain an independent evaluation of the correlation between target
and response data, the experimenters submitted the data for judging on a
"blind" basis by two SRI scientists who were not otherwise associated
with the research. For the ten cases in which Mr. Geller provided a
response, the judges were asked to match the response data with the
corresponding target data (without replacement) .
In those cases in which
Mr. Geller made more than one drawing as his response to the target, all
the drawings were combined as a set for judging.
The two judges each
matched the target data to the response data with no error. For either
judge such a correspondence has an a priori probability, under the null
hypothesis of no information channel, of p = (10!)~ ~ 3 x 10-7.
The quality of match between target and response in certain cases,
together with the overall probability of matching obtained by the judges,
constitute strong evidence for the existence of a potentially useful
information channel.
A second series of experiments was carried out to determine whether
direct perception of envelope contents was possible without some person
knowing of the target picture.
One hundred target pictures of everyday objects were drawn by an SRI
artist and sealed by other SRI personnel in double envelopes containing
black cardboard.
The hundred targets were divided randomly into groups
of 20 for use in each of the three days' experiments.
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On each of the three days of these experiments, Mr. Geller passed.
That is, he declined to associate any envelope with a drawing that he made.
On each day he made approximately 12 recognizable drawings, which he felt
were associated with the entire target pool of 100. He seemed to be
disturbed by the existence of such a large target pool. On each of the
three days, two of his drawings could reasonably be associated
with two of the 20 daily targets. On the third day, two of his drawings
were very close replications of two of that day's target pictures. We
consider that the drawings resulting from this experiment do not depart
significantly from what would be expected by chance, which appeared to
be Mr. Geller's conclusion also, leading to passes on his part.
Thus, it would appear that eliminating a person knowledgeable of the
target degrades the quality of the information channel.
However, based
on Mr. Geller's subjective impression, there is also the possibility tha.
advance preparation of a large target pool, in comparison with single
target preparation, results in cross talk -- i.e., diffuses the identity of
the target.
In a simpler experiment Mr. Geller was successful in obtaining
information in which no persons were knowledgeable of the target. A double
blind experiment was performed in which a single die was placed in a small
steel box. The box was then vigorously shaken by one of the experimenters
and placed on the table. The orientation of the die within the box was
unknown to the experimenters at that time.
Mr. Geller would then write
down his perception as to which die face was uppermost. Thus, in this
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case the target pool was known, but the targets were individually prepared
in a manner blind to all persons involved in the experiment.
This experi-
ment was performed ten times, with Mr. Geller passing twice and giving a
response eight times.
In the eight times in which he gave a response,
he was correct each time.
+
The probability of this occurring by chance
is approximately one in a million, (1/6)8.
To summarize the work with Mr. Geller, 5
we observe that in certain
situations significant information transmission can take place under
shielded conditions.
Factors which appear to be important and therefore
candidates for future investigation include whether the subject knows the
set of targets in the target pool, the actual number of targets in the
target pool at any given time, and whether the target is known by any of
the experimenters.
REMOTE VIEWING OF NATURAL TARGETS
In experiments carried out in our program to investigate the abilities
of a New York artist, Mr. Ingo Swann, he expressed the opinion that the
insights gained during experiments at SRI had strengthened his ability to
view remote locations that had been researched before he joined the SRI
program.
6
-
To test Mr. Swann's assertion, a pilot study was set up in which a
-1
The distribution of responses consisted of three 2s, one 4, two 5s, and
two 6s.
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series of targets from around the globe were supplied to the experimenters
by SRI personnel on a double-blind basis.
In our estimation, Mr. Swann's
ability to describe correctly details of buildings, roads, bridges, and
the like indicated that he could perceive remote locations, sometimes in
great detail, given only their geographic latitude and longitude. Thus,
we considered the descriptions were sufficiently accurate to warrant our
setting up a research program in remote viewing.
We present here the results of a remote viewing experiment, carried
out with a second subject in the remote viewing program, Mr. Pat Price,
a former California police commissioner and city councilman.
This experi-
ment consisted of a series of double-blind, demonstration-of-ability tests
involving local targets in the San Francisco Bay area which could be
documented by several independent judges. We planned the experiment
considering that natural: geographical places or man-made sites that h
existed for a long time are more potent targets for paranormal perception
experiments than are artificial targets prepared in the laboratory. This
is based on the opinions of Mr. Swann and Mr. Price that the use of
artificial targets involves a "trivialization of the ability" as compared
with natural pre-existing targets.
In each of nine experiments involving Mr. Price as remote-viewing
subject and SRI experimenters as a target demarcation team, a remote
location was chosen in a double-blind protocol. Mr. Price, who remained
at SRI, was asked to describe this remote location, as well as whatever
activities might be going on there.
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Data from the nine experiments are presented in the following para-
graphs. Final judging indicated that several descriptions yielded
significantly correct data pertaining to and descriptive of the target
location.
REMOTE VIEWING PROTOCOL
In the nine double-blind remote-viewing experiments, the following
procedures were used. An experimenter was closeted with Mr. Price at
SRI to wait 30 minutes to begin the narrative description of the remote
location.
The SRI locations from which the subject viewed the remote
locations. consisted of an outdoor park (Experiments 1,2), the double-walled
copper-screen Faraday cage discussed earlier (Experiments 3, 4, 6-9), and
an office (Experiment 5).
A second experimenter would then obtain a target location from an
individual in SRI management, the director of the Information Science and
Engineering Division, not otherwise associated with the experiment. This
location was either in the form of traveling orders previously prepared,
sealed, and randomized by the target selecter (Experiments 1, 2, 5, 6),
or by his driving the target demarcation team to the target himself without
any written indication (Experiments 3, 4, 7-9). The set of targets was
chosen from a target-rich environment by asking the selector to use his
judgment in providing a set of nine target locations which were clearly
differentiated from each other and within thirty minutes driving time
from SRI.
In all cases, the target demarcation team proceeded directly
to the target by automobile without communicating with the subject
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1

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or experimenters remaining behind. Since the experimenter remaining with
the subject at SRI was in ignorance both as to the particular target and
also as to the target pool, he was free to question Price to clarify his
descriptions. The demarcation team then remained at the target site for
an agreed-upon thirty minute period following the thirty minutes allotted
for travel.
During the observation period, the remote-viewing subject
would describe his impressions of the target site into a tape recorder.
A comparison was then made when the demarcation team returned. To represent
best the detail and style of these narratives, we have included the entire
unedited text of one of the better narratives containing very few incorrect
statements, Experiment 7, in an appendix.
In general, the descriptions contained inaccuracies as well as correct
statements. To obtain a numerical evaluation of the accuracy of the rem .te
viewing experiment, the nine original target locations were subjected to
independent judging on a blind basis by five SRI scientists who were no'
otherwise associated with the research. The judges were asked to match
the nine locations, which they independently visited, against the typed
manuscripts of the tape-recorded narratives of the remote viewer. The
transcripts were unlabeled and presented in random order. The judges
were asked to find a narrative which they would consider the best match
for each of the places they visited. A given narrative could be assigned
to more than one target location. The hypothesis is that the judges,
when asked to match the actual targets with the transcripts, would place
the actual target in the most favored category more often than they
would be expected to by chance. Table 2 shows the distribution of the
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..
PLACES VISITED BY JUDGES
DESCRIPTIONS CHOSEN
BY JUDGES
1
2
3
4
5
6
7
8
9
Hoover Tower
1
$
ABC
DE
D
Baylands Nature
Preserve
2
ABC
E
D
D
Radio Telescope
3
ACD
BE
Redwood City Marina
4
CD
ABD
E
E
Bridge Toll Plaza
5
ABD
DCE
Drive-In Theatre
6
B
A
C
E
Arts and Crafts
Garden Plaza
7
ABC
E
Church
8
C
AB
Rinconada Park
9
CE
AB
TABLE 2.
Distribution of correct selections by Judges A, B, C, D, and E in remote
viewing experiments. Of the 45 selections (5 judges, 9 choices),
24 were correct.
Boxes heavily outlined indicate correct choice.
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judges' choices. For purposes of display we present the table such that
the main diagonal corresponds to the correct choices. The number of
correct matches by judges A through E is 7, 6, 5, 3, and 3, respectively.
The expected number of correct matches from the five judges was five; in
the experiment twenty-four such matches were obtained.
Among all possible analyses, none is more conservative than a
permutation analysis of the majority vote of the judges' selections
assuming assignment without replacement. By majority vote, six of the
nine descriptions and locations were correctly matched.
Under the null
hypothesis (no remote viewing and a random selection of descriptions
without replacement), this outcome has an a priori probability of p =
5. x 10-4, since, among all possible permutations of the integers one
though nine, the probability of six or more being in their natural
A
tion in the list has that value.
Therefore, although Price's descrip-
Mis contain inaccuracies, the descriptions are sufficiently accurate
ti
to permit the judges to differentiate among the various targets to the
degree indicated.
EEG EXPERIMENTS
An experiment was undertaken to determine whether a physiological
measure such as EEG activity could be used as an indicator of information
transmission between an isolated subject and a remote stimulus. We
hypothesized that perception could be indicated by such a measure even
in the absence of verbal or other overt indicators.
7,8
In other words,
this experiment examines the hypothesis that perception may take place
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at noncognitive levels of awareness and be measurable, even though not
expressed verbally.
It was assumed that the application of remote stimuli would result
in responses similar to those obtained under conditions of direct stimu-
lation.
For example, when normal subjects are stimulated with a flashing
light, their EEG typically shows a decrease in the amplitude of the resting
9
rhythm and a driving of the brain waves at the frequency of the flashes.
We hypothesized that if we stimulated one subject in this manner (a sender) ,
the EEG of another subject in a remote room with no flash present, (a
receiver), might show changes in alpha (9-11 Hz) activity, or possibly
EEG driving similar to that of the sender.
Applying this concept, we informed our subject that at certain times
a light was to be flashed in a sender's eyes in a distant room, and if
the subject perceived that event, consciously or unconsciously, it might be
evident from changes in his EEG output.
The receiver was seated in the
visually opaque, acoustically and electrically shielded double-walled steel
room previously described.
The sender was seated in a room across the hall
from the EEG chamber at a distance of about 7 meters from the receiver.
In order to find subjects who were responsive to such a remote
Stimulus, we initially worked with four female and two male volunteer
subjects, all of whom believed that success in the experimental situation
might be possible.
These were designated "receivers."
The senders were
either other subjects or the experimenters.
We decided beforehand to
run one or two sessions of 36 trials each with each subject in this
selection procedure, and to do a more extensive study with any subject
:
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whose results were positive.
A Grass PS-2 photostimulator placed about 1 meter in front of the
sender was used to present flash trains of 10 sec duration.
The receiver's
EEG activity from the occipital region (Oz), referenced to linked mastoids,
was amplified with a Grass 5P-1 preamplifier and associated driver
amplifier with a bandpass of 1 to 120 Hz.
The EEG data were recorded on
magnetic tape with an Ampex SP 300 recorder.
On each trial, a tone burst of fixed frequency was presented to both
sender and receiver, and was followed in one second by either a ten-second
train of flashes or a null flash interval presented to the sender. Thirty-
six such trials were given in an experimental session, consisting of 12 null
trials -- i.e., no flashes following the tone -- 12 trials of flashes at 6 fps,
12 trials of flashes at 16 fps, all randomly intermixed.
Each of the
t: . als generated an 11-second EEG epoch. The last 4 seconds of the epoch
...
wa, selected for analysis to minimize the desynchronizing action of the
warning cue. This 4-second segment was subjected to Fourier analysis on a
LINC 8 computer.
Spectrum analyses gave no evidence of EEG driving in any receiver,
although in control runs the receivers did exhibit driving when physically
stimulated with the flashes. However, of the six subjects studied
initially, one subject (H.H. ) showed a consistent alpha blocking effect.
We therefore undertook further study with this subject.
Data from 7 sets of 36 trials each were collected from this subject
on three separate days. This comprises all the data collected to date
with this subject under the test conditions' described above. The alpha
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band was identified from average spectra, then scores of average power
and peak power were obtained from individual trials and subjected to
statistical analysis.
Of our six subjects, H.H. had by far the most monochromatic EEG
spectrum.
Figure 3 shows an overlay of the three averaged spectra from
one of this subject's 36-trial runs, displaying changes in her alpha
activity for the three stimulus conditions.
Mean values for the average power and peak power for each of the
seven experimental sets were given in Table 3. The power measures were
less in the 16 fps case than in the 0 fps in all seven peak power measures
and in six out of seven average power measures.
Siegel's two-tailed t approximation to the nonparametric randomization
test
10
was applied to the data from all sets, which included two sessions
in which the sender was removed. Average power on trials associated with
the occurrence of 16 fps was significantly less than when there were no
flashes (t = 2.09, df = 118, p < . 04). The second measure, peak power,
was also significantly less in the 16 fps conditions than in the null
condition (t = 2.16, df = 118, p < . 03). The average response in the 6
fps condition was in the same direction as that associated with 16 fps,
but the effect was not statistically significant.
Spectrum analyses of control recordings made from saline with 12K
ohms resistance in place of the subject with and without the addition of
a 10 Hz, 50 uV test signal applied to the saline solution, revealed no
indications of flash frequencies, nor perturbations of the 10 Hz signal.
These controls suggest that the results were not due to system artifacts.
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0
6
VOLTAGE - . arbitrary units
16
·
5 Hz
10 Hz
15 Hz
THREE CASES - 0, 6 and 16 Hz flashes (12 trial averages)
FIGURE 3 OCCIPITAL EEG FREQUENCY SPECTRA, 0 TO 20 Hz, OF ONE SUBJECT (H.H.)
ACTING AS RECEIVER SHOWING AMPLITUDE CHANGES IN THE 9-11 Hz BAND
AS À FUNCTION OF STROBE FREQUENCY
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Flash
Frequency
Average Power
Peak Power
Sender
0
6
16
0
6
16
J.L.
94.8
84.1
76.8
357.7
329.2
289.6
R.T.
41.3
45.5
37.0
160.7
161.0
125.0
No Sender
(Subject informed)
25.1
35.7
28.2
87.5
95.7
81.7
J.L.
54.2
55.3
44.8
11
191.4
170.5
149.3
J.L.
56.8
50.9
32.8
240.6
178.0
104.6
R.T.
39.8
24.9
30.3
11
145.2
74.2
122.1
No Sender
(Subject not
informed)
86.0
53.0
52.1
318.1
180.6
202.3
Averages
56.8
49.9
43.1
214.5
169.8
153.5
-12%
-24% (P <. 04)
-21%
-28% (P <. 03)
.
TABLE 3.
.
EEG data for H.H. showing average power and peak power in the
9 - 11 Hz band, as a function of flash frequency and sender.
Each table entry is an average over 12 trials.
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Further tests also gave no evidence of radio frequency energy associated
with the stimulus.
Subjects were asked to indicate their conscious assessment for each
trial as to which stimulus was generated. They made their guesses known
to the experimenter via one-way telegraphic communication. An analysis
of these guesses has shown them to be at chance, indicating the absence
of any supraliminal cueing.
Thus, we note that in this pilot study, one of six subjects showed
significant EEG changes associated with the presence of remote stimuli
under conditions of sensory shielding.
This form of noncognitive arousal
evidenced by alpha blocking has also been observed by Tart (1963), using
.. small electric shock stimulus applied to himself as sender in a similar
:
periment.
.7
We hypothesize that the protocol described here may prove
.
be useful as a screening procedure for latent remote perceptual ability
-
in the general population.
DISCUSSION
We have presented evidence for the existence of a biological informa-
tion channel whose characteristics appear to fall outside the range of
known perceptual modalities. The precise nature of the channel or
channels is as yet undefined, but may involve either direct perception
of hidden information content, perception of mental images of persons
knowledgeable of target information, precognition, or some combination
of these or other information channels.
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We have worked with three individuals, two of whom are reported on
in detail here, whose remote perceptual abilities were sufficiently
developed that they were able to describe both pictorial and geographical
material blocked from ordinary perception.
In addition to experiments which centered on subjects' conscious
perceptions, we have also conducted EEG experiments in which we have found
statistically significant evidence of direct physiological indications
of nonconscious perception of remote stimuli. The observation that a
nonconscious link with physiological correlates can exist between separated
individuals is one that merits considerable study.
From these experiments we conclude that
· A channel exists whereby information about a remote location can
be obtained by means of an as yet unidentified perceptual modality.
.
· As with all biological systems, the information channel appears
to be imperfect, containing noise along with the signal.
· While a quantitative signal-to-noise ratio in the information-
theoretical sense cannot as yet be determined, the results of our
experiments indicate that the functioning is at the level of
useful information transfer.
It may be that remote perceptual ability is widely distributed in
the general population, but because the perception is generally below an
individual's level of awareness, it is repressed or not noticed. For
example, two of our subjects (H. H. and P. P. ) had not considered themselves
to have unusual perceptual ability before their participation in these
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experiments. We conjecture that it is partially the prevailing philosophical
attitudes of the times in which we live that prevent such ability as may
exist from surfacing to a greater extent. Our shared cultural constraints
deny permission for the demonstration of such abilities.
With regard to the methodology itself, our observation of the phenom-
.
ena leads us to conclude that experiments in the area of so-called paranormal
phenomena can be scientifically conducted. The results presented here
offer a basis from which departures as a function of other observables
can be studied. Our goal for future experimentation is the investigation
of the physical and psychological laws underlying these phenomena, rather
than just the addition of further demonstrations of the statistical
hopearance of paranormal phenomena in the laboratory.
'KNOWLEDGMENTS
This research was sponsored by The Foundation for Parasensory Investi-
gation, New York City. We wish to thank its president, Mrs. Judith Skutch,
and their representative, Dr. Edgar D. Mitchell of the Institute of Noetic
Sciences -- as well as our SRI associates, Mr. Bonnar Cox, Mr. Earle Jones,
and Dr. Dean Brown -- for their support and encouragement throughout this
work.
We also wish to acknowledge Dr. Wilbur Franklin of Kent State Uni-
versity for his contribution, especially in the early phases of this research.
Finally, we acknowledge the many constructive suggestions provided us
through conversations with Mrs. Jean Mayo, Dr. Charles Tart, University of
California, and Dr. Robert Ornstein and Dr. David Galin of the Langley
Porter Neuropsychiatric Institute.
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REFERENCES
1. J. Pratt, J. B. Rhine, C. Stuart and J. Greenwood, EXTRA SENSORY PERCEPTION
AFTER SIXTY YEARS, New York, Henry Holt, 1940.
2. S. Soal and F. Bateman, MODERN EXPERIMENTS IN TELEPATHY, London, Faber
and Faber, 1954.
3. L. L. Vasilliev, EXPERIMENTS IN MENTAL SUGGESTION, Hampshire, England,
ISMI Publications, 1963.
4. J. R. Musso and M. Granero, "An ESP Drawing Experiment With a High-
Scoring Subject," J. of Parapsychology, Vol. 37, pp. 13-37, March, 1973.
5. It has been widely reported that Mr. Geller has demonstrated the ability
to bend metal by paranormal means.
Although metal bending by Mr. Geller
has been observed in our laboratory, we have not been able to combine
such observations with adequately controlled experiments to obtain
data sufficient to support the paranormal hypothesis.
6. K. Osis, ASPR Newsletter, No. 14, Summer, 1972.
7. C. T. Tart, PHYSIOLOGICAL CORRELATES OF PSI COGNITION, Intl. J. of
Parapsychology, Vol. V, No. 4, Autumn, 1963.
8. E.D. Dean, "Plethysmograph Recordings as ESP Responses," Intl. J. of
Neuropsychiatry, Vol. 2, October, 1966.
9. D. Hill and G. Parr, ELECTROENCEPHALOGRAPHY: A SYMPOSIUM ON ITS VARIOUS
ASPECTS, Macmillan, New York, 1963.
10. S. Siegel, NONPARAMETRIC STATISTICS FOR THE BEHAVIORAL SCIENCES, pp.
152-156, New York, McGraw-Hill Book Co., Inc., 1956.
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APPENDIX
Following is the unedited transcript of remote viewing Experiment 7,
where the target was an Arts and Crafts Garden Plaza,
This is a large
plaza resembling a California mission. There are craft shops around the
perimeter of the plaza, In the plaza area are many gardens, flowers,
ceramic pots, fountains, and paths. Overhead are vines on arbors of
redwood. Price's description is accurate in almost every detail and he
omitted little of importance.
1:40
THIS IS A REMOTE VIEWING EXPERIMENT WITH PAT PRICE, DEAN BROWN,
AND RUSSELL TARG IN THE SHIELDED ROOM IN BUILDING 30. THE TRAVELLERS TO
REMOTE LOCATION ARE BART COX, HAL PUTHOFF, JUDY SCHMICKLEY AND PHYLLIS
COLE.
WE EXPECT THE TRAVELLERS TO BE AT THEIR PLACE IN ABOUT 10 MINUTES.
IT'S 1:58.
OUR TRAVELLERS SHOULD BE NEAR TO ARRIVING AT THE PLACE,
Why don't I start scanning by quadrant using this as a center point.
2-3, 6-9 ..
. ..
11 go from 12-3 first. Seems to me right now that I'm picking them up
in the 12-3 quadrant, but I'll go on in the rest and look.
I haven't
ctually identified them, I just feel that they're there.
:ope, I don't get them there.
Now I'll go from 6-9.
While I was looking at 6-9, it looks to me like
I'm looking at an iris, a flower of some kind, I'll come back and
identify that later. Just wanted to get it down as having a flash of
an iris flower-purplish.
I'll continue to scan that quadrant.
Nope,
don't get them there.
I'll go from 9-12.
Don't get them there.
I'll go back 12-3. Yeah, I get them in that quadrant.
Now I'll see if I can locate them physically and identify the area.
I'm looking at something that looks like an arbor, trellis-work arbor.
Seems to be cool,
shaded.
Doesn't seem to me that they're out in the
direct sunlight.
Be more like there's lots of trees, in an arbor area.
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The arbor appears to be made of wood, possibly redwood.
They're just. ... looks like it's a dirt path, quite wide, I'd say
maybe 12 feet. I can see some grass. Looks like possibly a fountain
of some kind.
Yeah, I can see Bart in his red shirt and what looks like kind of a
gray paisley tie - I didn't really look at that when he was down
there.
The red shirt, I did. Looks like he has on a gray paisley
tie.
It appears they're walking along quite leisurely.
Looks like there's some red brick laid into a walkway.
They don't
seem to be on it, they just seem to pass over that.
I get - it seems like a little ways away from them there are quite
a few people but right where they're walking it doesn't appear to
be many right in there.
This is an arbor area. Back of that arbor, back here I'd say 50 feet
from that arbor to here, seems to be a lot of people in here. They
were walking along here on what looks like about a 12 foot dirt path.
WHAT KIND OF PLACE IS THE ARBOR IN? IS IT A FIELD OUT IN THE OPEN?
No. I want to say park, but it doesn't exactly feel like a park.
If
you took a - the feeling I'm getting - it's not the specific place -
but like the Town and Country Market. That type of an atmosphere,
with quite a section of it into a little outdoor park, but basically
I'm getting a very strong feeling of flowers.
Like the first one I saw was an iris.
TELL ME ABOUT THE TOWN AND COUNTRY ASPECT. IN WHAT WAY DOES IT REMIND
YOU OF TOWN AND COUNTRY.
The buildings, not right where they're at, but very close to them have
that same kind of architecture and look. The parking lot looks similar,
grand, sweeping, not cluttered, it's more expansive area. You take a
place like Sears Mall - it seems cluttered. This seems more leisurely
paced.
People are moving about slower - there's not the hustle and bustle -
more or less meandering.
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TOWN AND COUNTRY MEANS TO ME A COVERED WALKWAY.
Yeah, the back of them it seems to be - where they are seems to be a
very large arbor like vines growing over it and things, and there possi-
bly - I haven't looked in there yet to see if there's any displays like
pottery and things - I get the feeling that there is right close to it.
ALSO, OUTDOORS?
Yeah, it seems like fairly high shade trees - kinda bordering.
The center
part doesn't seem to have it - this part in here. The trees seem to be
way up in here along like this over here. This seems to be shaded in
here, but it's sunny out here.
I just saw something that looked like a windmill - not a farm type wind-
.
mill - a Dutch-type windmill.
It's smaller - it's not a huge thing, but
I'm getting a definite feeling that it's like a windmill.
The area in there feels damp - not wet - they're not walking in water,
but it's very moist.
'he temperature in there. .. it's secluded.
Feels very comfortable.
A
ittle on the shady side.
HAT DO YOU FIND AS THE BOUNDARIES OF THE PLACE THEY'RE AT?
Outside of this little park-like affair that they seem to be in, there's
1 street. One side of it seems to be a kind of a residential. . . the other
seems to be a little bit more heavily travelled.
Let me pick up a little bit more.
I can see one very large oak tree - exceptionally large.
Right now Bart is trying to point something out that is basically the
significance of the whole place. It's like that key thing, well, if
you'd have mentioned a salt pile I'd have blown my lid. Well, this has
a significance that's just about comparable to that. I'm screening it
out.
Thing that just flashed in was kind of like a stadium structure - like
looking down into a stadium.
Just when I did that I - I'll have to reorient to make sure I'm looking
in the same area now ..
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Seems like they're - I still get them in the same quadrant I had them
in originally. Seems like some decorative brick walls.
THE QUADRANT YOU HAD THEM IN IS BASICALLY THE NORTHEAST QUADRANT?
Yeah, I got them out about this far - it's not far away - I'd say in
this direction over here about - feels like a mile to a mile and a half.
They don't feel as far away, and I'm not looking at the time continuum.
They actually don't feel as far away. I'd say that it is about - not
half the distance they were to the marina, and it seems to be on a line
just about in that direction but just a hair more - rather than a direct
line from here to the marina - they seem to be just slightly more to the
left of that line.
I was looking back to where he had the car parked and it seems like it's
on asphalt
then a curb in front, and then it's like a dirt walkway and
then a sidewalk. But I can see eucalyptus buds on the ground and some
branches of eucalyptus there.
One of the most dominant things to me in the way of unusualness is the
size of the oak tree that I'm looking at. Looks like an arboretum, or
I get the definite feeling of flowers.
Almost get the feeling like it's commercial flowers.
In fact, the most predominant feeling that I'm getting right now is flowers.
Don't know why iris particularly.
There's something about the windmill that I was going to look at. Wasn't
that what you were. . . .?
Be like one you'd almost see in a miniature golfcourse ... the windmill.
Has all the construction and detail but not as large - it's fairly small.
Seems to be made out of dark redwood and it's kind of aged.
I'm going to try to look more directly to them.
Let's see, there's Bart
and Hal, and behind Bart is Judy and behind Hal is Phyllis, kinda stag-
gered there.
Looks like a possible small pool of water - like a garden pond.
Looks like a little bridge.
4
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I was trying to get the feeling of what type of an area it was.
Let me elevate a bit. I'm looking at much too small an area. There's
some greater significance there that I feel I'm definitely not looking
at - let's jack up a bit ... maybe 500 feet.
I see a lot of trees.
I see Judy's red hair and her brown eyes and her flashing teeth - she
has beautiful teeth.
Hadn't really looked at them before.
Phyllis and her are talking about something and Hal and Bart are talking
about something and he's pointing at something and it seems to me that
he's pointing over to what I'd call a windmill or something that looks
like a windmill.
The water I see looks more like a pool or a pond than it does - you know,
it's not big like a lake - not very large, but it looks like a definite
pool.
ight where they're at I don't hear too much traffic noise - it seems
be fairly quiet.
Looks like a little wooden walkway.
, eels a little early, but it kinda seems like they're retracing their
teps heading back toward the car, but they're still moving quite leisurely.
IF YOU LOOK DOWN ON THE PLACE FROM ABOVE, CAN YOU GET ANY FEELING FOR
THE - IS THERE ANY OVERALL LAYOUT OR PLAN?
When I went up I could see trees and stuff, and I kind of got the feeling
of like in a corner of a golf course, you know - where there would be a
lot of trees overhanging the green and some things in there - that seemed
to be out of context, but when I elevated, that's what I got. It kind
of looked like an overlap to me, so I didn't talk about it, but I will.
When I elevated it kind of felt like it was right over the corner of a
golf course of some kind, with a street running down one side, and they
are fairly close to that.
In fact, the bricked area that I looked at or like a patio thing kinda
looks like a walkway. Seems like there's small building - small meaning
not tall - looks like a single story building. Looks like it has a flat
roof - slightly pitched. Looks like 4 x 4 poles supporting it - has a
5
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canopy out over it.
They're painted white, place looks like very possible
light yellow or cream color.
They're walking not too far from that.
Still seems to me that they're
on a dirt pathway.
In the area that they're in now I get
flowers again - where before they
kinda fell out of the flowers.
Looks like maybe 80-100 yards from where they are - looks like 2 guys
on a motor scooter.
They can see them.
WHAT WOULD YOU SAY IS THE INTEREST TO THIS PLACE?
WIIAT'S SPECIAL ABOUT
THIS PLACE?
It seems to be a kind of a recreational, relaxed ... not energetic - looks
more relaxed. I'd say it's kind of combination recreational and relaxation
area that I'm getting out of it.
That would be the general character of it.
Two aspects - one is aesthetics and the other is a kind of a mild recre-
ational area.
There seem to be some unique features - I don't have it totally into
context as yet .
There's a number of things that I've rejected - looked
at and rejected saying.
First, I got the impression that it was kind of like a miniature golf
course - I rejected that. Merely from saying it - I didn't reject the
principle - I just rejected saying it.
Then I kind of got the idea of a standard golf course - I also rejected
that on the same principle, so I'm just trying to describe the terrain.
Seems expansive - doesn't seem cluttered.
Just got a flash of something that reminded me of the gyroscope - gimbals
on the gyroscope.
Drinking fountain - looks like it's made out of kinda like field stone
built up into a fountain ... bowl.
I'm going to elevate again and go through a search quadrant again.
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I still get them in that general location, so that seems to set all right.
Distance - maybe a mile, mile and a half.
Doesn't seem much farther-
Seems fairly close.
The area has an awful lot of grass, lot of trees - looks like dirt walk-
ways, well trimmed.
I can see the arbor, and the arbor could be a place
to sit and be out of the direct sun.
May be a few little tables and benches and chairs in there.
That outlooks over quite a grassy area - there are quite a few trees.
I see basically an oak.
Right after they got out of the car I could see some eucalyptus buds
and branches on the ground, and it seemed like the trees were there.
Looked like they got out of the car, stepped upon a curb, dirt parkway,
a sidewalk, and then they went into this area.
I get the feeling this windmill type thing - that all seems fairly real.
The feeling is still that it's relaxing and has some recreational aspects -
[ just haven't put it totally together as to giving it a name.
Right now I get a very strong impression of flowers again.
It seems like right now they're back to right where I originally spotted
them only they're going in the opposite direction - like they're moving
toward the direction they originally went.
While they were there they walked on several pathways - walked out quite
a ways, then swung over and come over and worked around and looked at ...
One peculiar thing I might note - so far I haven't sensed, seen nor heard
an airplane.
Cars seem quite distant - outside of that little motor scooter affair
with the two guys on it.
That's about the only vehicular traffic I've
seen - except out in the parking lot.
It seems like to me that they've got most of their attention off what
they were looking at and they've got their attention more on the car
now.
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I want to look and find out what the significant thing was that Bart
was talking about.
There's something quite unusual there and I . . .
Damned if I can pick it
up.
WAS HAL DOING ANYTHING BESIDES WALKING ALONG - WAS THERE ANY ACTIVITY
FOR HAL TO DO?
Most of the time I was looking at Hal, he was kind of listening to Bart
and Bart was pointing out a number of things.
Part of the time Bart was walking with Hal; part of the time he was back
by Judy.
When I first saw them, it was Bart in the front on the left side, Hal
was on his right, Judy was slightly behind - almost between Bart and
Ilal but behind, and Phyllis to her right.
They wandered around but the first time I picked up - they were that
way.
When they were coming back, they just about reversed.
Bart would be in
front. When they were coming back, it looked like Bart was in front
with Phyllis, and Judy was walking more behind Bart and Hal on her right
when they were coming back out of there.
They're actually at the car.
2:30
SHALL WE GO DOWNSTAIRS AND SEE HOW THEY'RE DOING?
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Perception & Psychophysics
1973. Vol. 14. No. 2. 313-318
A study of sine-wave contrast sensitivity
by two psychophysical methods*
CPYRGHT
D. H. KELLY and R. E. SAVOIE
Stanford Research Institute. Menlo Park. California 94025
In the literature on visual contrast thresholds for sine wave gratings. little attention has been paid to the
psychophysical methods used to obtain these spatial-frequency response curves. Here we report a comparison of such
data obtained by two quite different psychophysical methods, but otherwise under identical conditions. using five Ss.
Both experiments were run by computer: (1) In the method of adjustments. the computer program merely controls the
order of the stimuli and records S's contrast settings. (2) In the forced-choice staircase (FCS) technique. the program
determines how often S can discriminate the sinusoidal grating from a uniform field, informs S of his accuracy. control
the stimulus contrast on the basis of S's preceding responses, and brackets his threshold by a series of successive
approximations. Method 2 eliminates criterion effects that occur in Method 1. and hence tends to minimize individual
differences. However, the FCS technique requires an order of magnitude more observing time to obtain equally
smooth contrast sensitivity curves. FCS also increases the overall sensitivity of some Ss by as much as five times, but it
does not significantly change the shape of the contrast sensitivity curve; both methods show strong effects of lateral
inhibition at low spatial frequencies.
Measurements of the contrast threshold for a
sinusoidal grating as a function of its spatial frequency
have been used to study the effects on the visual process
of optical. neural. chromatic, temporal, and other
factors. Van Meeteren (1966) has reviewed a number of
these studies. We are particularly interested in the
wow-frequency region of such data, below about 2
ycles/deg (cpd), because the monotonic increase of
ontrast sensitivity with increasing spatial frequency in
lis region may represent a simple form of lateral
hibition (Kelly, 1973).
In certain cases, little or no low-frequency falloff was
eported (e.g., Westheimer. 1960; Campbell & Green,
1965). but this has been attributed to the use of small,
sharp-edged targets (Davidson, 1966; Kelly, 1970) or
flash presentations (Kelly, 1971, 1973), which are
unsuitable for isolating the steady-state response to very
· low spatial frequencies. However, some Ss report that
the task of detecting a low-frequency grating seems
different from the high-frequency detection task; this
raises the question of whether the apparent inhibition
would persist at low frequencies if criterion effects were
eliminated.
Many of the data in the literature have been obtained
by the psychophysical method of adjustments, which is
the easiest and fastest procedure when Ss are
experienced in this type of judgment: variations of the
method of limits have also been used. But more
sophisticated psychophysical methods
have been
developed in recent years which are essentially
independent of threshold criterion: these have not been
*Our work was partly supported by NIH Grant No. NS-08322
and NSI Grant No. GB-1157]. Some of the data were reported
at the October 1971 meeting of the Optical Society of America
in Ottawa. Canada. We thank T. N. Cornsweet for suggesting this
study.
applied to the measurement of sine wave contrast
thresholds. We therefore undertook to compare the sine
wave thresholds obtained by the method of adjustments
with those obtained by a forced-choice staircase (FCS)
paradigm, in which the S was always informed of the
correctness of his choice. Our main purpose was to find
out
whether the low-frequency inhibition was
independent of criterion effects, but our results are also
relevant to other sine wave contrast experiments that use
subjective judgments.
:
METHODS
The stimulating apparatus is described in detail elsewhere
(Kelly, 1966, 1972); its components are shown schematically in
Fig. 1. S is seated comfortably. viewing a cathode ray tube
(CRT) 50 em distant through an artificial pupil. 2.3 mm in diam.
He sees an 8-deg circular field. filled by a vertical sinusoidal
grating. The spatial frequency of this grating is controlled by a
(LINC 8) computer. The dependent variable is the Michelson
contrast (m) of the grating. defined as
Bmax - Bmin
m =
Bmax + Bmin
where Bmax and Bmin are the maximum and minimum values of
the stimulus waveform. in trolands (td) of retinal illuminance.
This contrast is under the control of either the computer or the
S. depending on the mode of operation. Since the grating does
not flash or flicker in the present experiments, our temporal
waveform source was not used (see Fig. 1).
Adjustments Mode
In the method of adjustments. the S controls the contrast of
the grating. using a geared-down potentiometer without stops or
other mechanical cues. Spinning the knob about 1.200 deg
covers the entire adjustment range, which may be either 0-1 or
0-0.1 contrast. depending on a switch controlled by the S.
Another switch gives him the option of viewing zero or full
contrast at any time, without losing his potentiometer setting.
When the setting meets his threshold criterion, he pushes a
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'CPYRGHT
314
KELLY AND SAVOIE
BLAD
SUBJECT
A C
SCANNING
VERTICAL 1 VHI
SPATIAL
1.VC 8
CCYPUTER
-PATTERN
CHT
CRYSTAL CLOCK
BLANKING AND SYNC!
MULTIPLY
CONTRAS'
ATTENUATOR
TEMPORAL
WAVEFORV
SAYPLE
PEDESTAL
SC. RCE
AVO
HOLD
(s) METHOD OF ADJUSTMENT
VASKEA TI NE
SUBJECT
CHOICE
SCANNING
HORIZONTAL 1 &H;
VERTICAL 1 MHZ
SPATIAL
PATTERN
CRT
SOURCE 1
CHYSTAL CLOCK.
BLANKING ANO SYNC
MULTIPLY
CONTRAST
ATTENUATOR
FACING
PEDESTAL
'hl FORGED.CHOICE STAIRCASE METHOD
Fig. 1. Signal-flow diagrams of the CRT stimulator.
(a) Configuration for method of adjustments. (b) Configuration
for forced-choice staircase (FCS) procedure.
button which enters this contrast into the computer.
He is instructed to fixate the center of the grating and to find
the contrast at which it can just be discriminated from a uniform
field. (This criterion, which we always use for sine wave
thresholds, should come close to matching S's performance in
the forced-choice task described below.)'S spends as much time
as he wishes "hunting" back and forth to find his threshold. but
we instruct him to make his final judgments only in the steady
state: i.c., after he has refrained from changing the contrast for
several seconds. Twelve spatial frequencies were tested in one
experimental session; each pattern was presented five times in
random order. for a total of 60 judgments. The means of these
five settings gave fairly smooth spatial-frequency response
curves. as described below. An experienced S can complete such
a run in 20-25 min.
Forced-Choice Staircase (FCS) Mode
Our criterionless psychophysical procedure combined the
staircase method of ordering stimuli (Bekesy. 1947: Cornsweet.
1962) with the forced-choice method of response collection
(Blackwell. 1946; Heinemann, 1961). In this application. the
two techniques complement each other in such a way that S
spends most of his time making discriminations near threshold.
The S's task is much simpler in the FCS mode. The same 12
stimulus patterns are used, but their contrast is now under the
control of the computer. One stimulus cycle consists of two
successive intervals. each 5 sec long: a pattern of nonzero
contrast is presented in only one of these intervals. which is
determined by the computer from a table of random numbers.
One second after the beginning of each interval. a marker tone
sounds to notify S that the stimulus may be visible. He makes his
choice of interval by pushing a button, which also starts the next
trial: but this button has no effect until after the second tone. In
other words. S must make a choice in order to start a new trial.
but he cannot do so until after the second interval has started.
As soon as he makes his choice, he hears a pleasant tone
(different from the marker tone) if he is correct or an unpleasant
noise if he is not.
His only other control is a "pause" switch. which interrupts
the experiment for rest periods. S may use this switch also to
abort a given trial (if. for example, he happened to be looking
away when the marker tone sounded). The aborted trial is
repeated when the pause switch is reset. but the stimulus will not
necessarily occur in the same interval.
In order to avoid transient effects (Kelly. 1971. 1973), as we
do in the adjustments mode, the temporal waveform of the FCS
stimulus is carefully controlled. The mean luminance of the CRT
screen is held constant throughout the experiment. When a given
pattern is presented, its contrast is smoothly "faded in" from
zero to whatever value is set by the computer. as shown in
Fig. 2a. The temporal envelope of the fade-in waveform
resembles a half-cycle of a 0.5-Hz cosine wave, so that the full
contrast of the pattern is present after 1 see ( this contrast always
being zero in either the first or second interval. at random). The
pattern is also faded out the same way.
All 12 staircases are independent and randomly interleaved.
which helps to eliminate subjective bias effects (Cornsweet.
1962). On each trial. the contrast of the FCS stimulus is
contingent on the correctness of the preceding responses to the
same pattern. according to an algorithm described in detail in the
Appendix. When the responses indicate that S can detect the
pattern. the contrast is decreased; when he cannot. the contrast
is increased, by a constant logarithmic increment in either case.
Thus, the contrast is forced to cross and recross the threshold
level (which is about 755% correct). At first. the size of the
increment is decreased each time the response sequence indicates
that a contrast increase has probably crossed S's threshold, But
the third time this indication occurs. the smallest increment
(30% contrast change) is maintained and the staircase is
terminated with a fixed number of additional trials.
A typical staircase illustrating these properties is shown in
Fig. 2b. Each stimulus is first presented at full contrast. to
familiarize S with its appearance and to provide a suprathreshold
baseline. If he detects it correctly. its next presentation is at a
contrast of 0.02; the staircase then enters the main algorithm
(see Appendix).
10
-
0 1
First Interval
CONTRAST
0
5
10
CONTRAST
001
0 001
.
0
5
-
10
1
5
10
15
20
TIME - Seconds
TRIAL WYBER
Marker Tones Olive at the Arrow
"m" is Contru"ed by the Contrast A Jard'un
Stimulus Occurs in the First of Second
Interval at R .- ndum
(a) FORCED . CHOICE PRESENTATION CYCLE
thl TYPICAL STAIRCASE
Fig. 2. Details of the FCS procedure. (a) Temporal waveform
of one stimulus cycle and timing of alerting tones. (b) A single
staircase. reassembled to show all contrasts presented. increment
sizes, wrong responses, and calculated threshold.
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CPYRGHT
Several hundred trials are required to terminate all 12
staircases; an experimental session usually takes 65-75 min.
regardless of the skill or experience of the S. Most of the
variability in length of the individual staircases (Rose et al. 1970)
is averaged out by the large number of staircases being run
simultaneously. 1
The threshold for each pattern is calculated as the mean of the
last eight contrasts presented. no adjacent pair of these being
separated by more than the smallest increment. The intersession
variability of FCS data obtained in this way is no greater than in
the adjustment mode. but is mainly random rather than
systematic. Thus, to obtain equally smooth spatial-frequency
response curves, one must average the data from three FCS
sessions, as described below.
RESULTS
Figure 3 shows some
contrast sensitivity data
obtained with a 20-year-old emmetropic naive S. The
upper curve (filled circles) represents combined data
from three FCS runs; three comparable adjustment
curves are plotted separately (open circles). These data
are typical of our results in three ways. First, the shape
of the FCS curve is essentially the same as that of the
adjustment curves: in both cases. the contrast sensitivity
increases steeply at low spatial frequencies, to a
. aximum near 4 cpd. Second, the FCS sensitivity is
stematically greater than that in any of the adjustment
. is. by a factor of 2 to 5. Third. there are also
istematic differences among the individual adjustment
ves. but these are smaller than the FCS-adjustment
ferences.
The lowest sensitivity in Fig. 3 represents the first
0.002
Subj. KS
0.005
0.01
CONTRAST
0.02
0.05
0.1
-+- FCS
Adjustments
0.2
-- 1st Run
-- 2nd Run
--- 3td Run
0.5
0.2
0.5
1
2
5
10
SPATIAL FREQUENCY (cpd)
Fig. 3. Contrast sensitivity vs spatial frequency for S K.S.
Retinal illuminance. 1.300 td: artificial pupil. 2. mm. Filled
circles are the means of three FCS runs. Open circles represent
three successive adjustment runs.
SINE-WAVE CONTRAST SENSITIVITY
315
Subj. DK.
0.005 L-
0.01
1
CONTRAST
0.02
.
0.05
0,1
-
FCS
0.2
-o- Adjustments
T
1
!
0.2
0.5
1
2
5
10
SPATIAL FREQUENCY (cpd)
Fig. 4. Contrast sensitivity vs spatial frequency for S D.K.
Same conditions as Fig. 3.
experiment with SK.S. Her adjustment sensitivity
increased subsequently, but leveled off between the
second and third adjustment runs. Typically, a naive S.
starts with a high threshold criterion. which he then
lowers after some experience with the method of
adjustments. However, his adjustment thresholds seldom
get as low as his FCS thresholds; apparently he adopts a
criterion in the range of 90%-100% probability of
detection (compared to the 75% imposed by the FCS
mode).
Figure 4 shows a similar comparison for another S.
S D.K. (one of the authors) is somewhat atypical, having
had hundreds of hours of practice in experiments with
this particular apparatus. If practice lowers the
adjustment threshold, his adjustment sensitivity should
be greater than that of S K.S .; and it is. relative to his
FCS sensitivity. His adjustment sensitivity may still be
slightly less than his FCS sensitivity. but the two are
much closer together than they are for our other Ss.
Evidently he uses a lower threshold criterion. closer to
the FCS level. As in Fig. 3, the FCS curve in Fig. 4 was
obtained by averaging data from three sessions. a total of
about 3.5 h observing time.
However, the contrast sensitivity curves obtained
from individual FCS sessions are also instructive: these
are shown for a third S in Fig. 5. Each of the dashed
curves in this figure connects the end points of the 12
staircases obtained in a single experimental session (see
Fig. 2b). The mean curve for these three FCS sessions is
shown for comparison with the previous figures.
Figure 5 also shows some systematic variation among
three adjustment runs for this S. (S H.P. was more
experienced than K.S .. but even an experienced S will
not always hold the same adjustment criterion from one
run to the next.) Again. the FCS sensitivity is about five
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CPYRGHT
316
KELLY AND SAVOIE
-
0.002
Subj. HP
0.005
.
0.01
CONTRAST
0.02
0.05
-+- FCS
0.1
Adjustments
-- 1st Run
0.2
-- 2nd Run
3rd Run
0.2
0.5
1
2
5
10
SPATIAL FREQUENCY (cpd)
Fig. 5. Contrast sensitivity vs spatial frequency for S H.P.
Same conditions as Figs. 3 and 4. Dashed lines show data from
three FCS runs, averaged to obtain filled-circle points.
times greater than the adjustment sensitivity.
The most important result shown in Fig. 5 is the
nature of the variability among FCS runs and among
adjustments runs. Although the FCS data are about as
variable as the adjustment data, the adjustment
variability is mainly systematic, while the variability
among the FCS runs seems random. (Note that the FCS
curves from individual sessions cross and recross each
other and the mean curve several times.) The data were
subjected to a chi-square test of the hypothesis that
mean rank contrast sensitivity is independent of session
number. This hypothesis can be rejected for the
adjustments data (p <. 001), but cannot be rejected for
the FCS data (p = . 1).
Now, if the FCS method eliminates systematic intra-S
variability from one run to the next, and if this
intersession variability is caused mainly by changes in S's
criterion, then we would expect this method to
minimize the variability among Ss as well. The data
shown in Fig. 6 tend to confirm this expectation. Here
the mean FCS curve for S H.P. is repeated, together with
similar data for two other young, emmetropic Ss. Note
the close similarity among all three contrast sensitivity
curves, particularly at frequencies below 2 cpd. These
data (and others not reported here) all tend to confirm
the presence of a low-frequency inhibiting effect with a
relatively steep slope (about 2 in log-log coordinates).
DISCUSSION
Instructing S to try to detect any perturbation of the
uniform field may be important in making the
adjustment curves so similar in shape to the FCS curves.
One should not assume that our results would be
obtained if S were instructed to detect the presence of a
grating. or to report its orientation. count its fringes, etc.
The use of other subjective criteria can doubtless change
the shape of the sine wave threshold curve.
When minimum threshold values are not required. and
occasional criterion differences among and within Ss can
be tolerated. the method of adjustments is obviously
preferable. because it yields equally smooth curves in
about a 10th of the time required by the FCS method.1
However, the FCS method eliminates criterion
differences and provides information about S's
performance (not just his judgments).
Summarizing our results with five Ss. ranging from
naive to quite experienced: (1) Both methods yield the
same curve shape. but the FCS method gives
significantly greater sensitivity than that obtained by the
method of adjustments: the increase may be as great as a
factor of 5 (depending on S's adjustment criterion).
(2) Presumably because it is independent of threshold
criteria. the FCS method does not show systematic
changes of sensitivity from one run to the next (as the
method of adjustments sometimes does.) (3) The
variability of the FCS data is mainly random and can
therefore be made quite small by taking enough data.
(4) When this is done, individual differences (among
young, emmetropic Ss) tend to disappear.
These results are essentially what would be expected.
based on the differences between the two
psychophysical methods. We conclude that. if the S is
appropriately instructed, the shape of his sine wave
grating sensitivity curve is not affected by using the
method of adjustments. Moreover, it seems likely that
this negative result would be maintained if the present
study were extended to other criterion-dependent
0.002
Forced-Choice Staircase
0.005
CONTRAST
0,01
0.02
0.05
-0- Subj. HP
-- Suhj. EB
0.1
-O- Subj. RS
-..
!
0.2
0.5
1
2
5
10
SPATIAL FREQUENCY (cpd)
Fig. 6. Contrast sensitivity vs spatial frequency for three
young, emmetropic Ss. obtained by the FCS technique.
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CPYRGHT
SINE-WAVE CONTRAST SENSITIVITY
317
SELECT NEW
STAIRCASE
EXECUTIVE
.-
INTERFACE
CONTROL
3
SAVE DATA
Y
WAR
SEQUENCES
YETİ
.
1. 4.B:T
F: ETHER
SELECTION
Y
LAST 3
PRESENTATIONS
COLE1
RESPONSE
HISTORY
WAS
PRESENT RESPONSE
RIGHT?
Yes
WAS
LAST RESPONSE
RIGHT?
Y.s
"RR"
1.15
RESPONSE BEFORE
THAT RIGHT'
3,0
WYRA"
SEQUENCE
7
Yes İ
"RRR"
SET I.CREME.T
TO NEXT
SMALLER VALUE
INAS
CONTRAST CHANGED
LAST TIME
2
VJ
Yes
Yes
WARK CONTRAST
NOT CHANGED
---
INCREASE COM. TRAST
EY INCFEVENT
DECREASE CONTRAST
BY INCREVER.T
Fig. 7. Flow-chart representation of the FCS computer program.
psychophysical methods in general. Thus, our results
tend to support the sine wave threshold data obtained
by these methods.
APPENDIX
The Forced-Choice Staircase (FCS) Computer Program
The operation of the FCS computer program can be
divided into five functional categories: executive.
interface control. staircase control. response history, and
contrast change ( see Fig. 7).
The executive section of the program initializes the
experiment. selects ( from a random table) one of the 12
stimulus patterns for presentation at each trial. performs
various bookkeeping functions. and calculates and prints
out the average data at the end of an experimental
session. The staircase control portion of the program
operates on a parameter table for the staircase currently
selected: it keeps track of the previous three responses.
the previous eight contrasts. the present contrast, and
contrast increment size (and other parameters for
internal use). These historical data are needed for each
staircase to determine its subsequent contrasts.
The interface control portion of the program controls
the stimulator interface. which operates the entire
sequence of each trial: stimulus generation. contrast
fading. marker tones. and reinforcement. When S makes
a response. the computer reads data from the interface.
indicating whether the response was right or wrong (or
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whether the "pause" switch was set ).
The response history section is the heart of the FCS
program: Fig. 7 shows a flow chart of this section and its
relation to the other parts of the program. Each staircase
follows the algorithm according to its own history,
independent of the other staircases. The next contrast to
be presented (for the selected staircase) is calculated on
the basis of the present contrast, the present response,
the previous two responses. the contrast increment, and
whether the contrast was changed after the previous
response. The contrast algorithm is as follows: ( 1) When
S makes a wrong (W) response, the contrast of that
pattern is increased for its, next presentation. After he
makes two successive right (R) responses to the same
pattern. its contrast is decreased (this sets the average
end point of each staircase at about 75% correct). The
new contrast is obtained by multiplying ( or dividing) the
preceding contrast by a fixed ratio (i.e., a constant log
increment). (2) Each time the sequence W.R,R occurs.
the size of this increment is decreased. (This is most
likely to occur when the contrast increases from below
to above the 75% correct level.) The successive
increment sizes are: 8X. 2X, 1.3X. (3) After the
sequence W,R,R has occurred three times with a given
pattern. the staircase terminates with three more trials
using the smallest increment, and that pattern is not
presented again. The session ends when all staircases
have terminated.
The last eight contrasts from each staircase are
averaged to obtain the threshold. The minimum number
of trials before termination but after the second W.R.R
sequence is eight. Therefore, all contrasts being averaged
were necessarily presented during the period when the
smallest contrast increment was in effect.
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Békésy. G. v. A new audiometer. Acta Oto-laryngologica, 1947,
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Blackwell. H. R. Contrast thresholds of the human eye. Journal
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Campbell. F. W., & Green, D. G. Optical and retinal factors
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Cornsweet. T. N. The staircase method in psychophysics.
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Davidson. M. A perturbation analysis of spatial brightness
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NOTE
1. Because the FCS sessions are long and tiresome. a number
of preliminary experiments were conducted to determine the
most suitable compromise between speed and end-point
stability. We found that the variability shown in Fig. 5 could not
be decreased significantly without prohibitive increases in run
length. The number and sizes of our increments were governed
by the following constraints (see Comsweet. 1963): (a) For
maximum efficiency, the smallest increment must be fixed at
about the same size as the contrast-difference threshold for
sinusoidal gratings; at a spatial frequency of 2.1 cycles/deg.
Kohayakawa (1972) obtained jnds of 30G to 60% with
low-contrast gratings. (Note that this is much larger than the jnd
of luminance.) (b) All staircases must start at a common
baseline; for this purpose. we chose 10057 contrast. (To start at
equal distances from threshold would require an a priori
assumption of the curve shape we are measuring. which could
bias the result.) (c) If the contrast is to approach threshold
quickly, the initial increment must be much larger than specified
in (a). The increment should decrease as the contrast approaches
threshold, but not so rapidly as to run a high risk of being
"trapped" in a small increment far from threshold. (d) Subject
to constraint (c), the total number of increments should be
minimized.
(Received for publication January 16. 1973:
accepted March 15. 1973:
revision received March 29. 1973.)
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