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Electro/77
Special Session
The State of the Art in
Psychic Research
Electro77 Professional Program
New York. April
19-21, 1977
Copyright^ 1977
Electro
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POSSIBLE EEG CORREIATES TO REMOTE STIMULI UNDER
CONDITIONS OF SENSORY SHIELDING
E .
C. May.* Russell Targ,
and H. E .
Puthoff
Stanford Research
Institute,
ABSTRACT
We have
investigated the ability of certain
individuals
to perceive remote
(faint)
stimuli
at
a noncognitive level of awareness.
To inves-
tigate
this we have looked for systematic
changes
in a subject's brainwave
(EEG) produc-
tion occurring
at the same time as light flashes
are generated on a random schedule
in a remote
laboratory.
Although we have found
in this
in-
vestigation that significant correlations
appear
to exist between the
times of light flashes
and
the times of brainwave alterations,
we consider
these data to be only suggestive, with
a defini-
tive result requiring further experimentation.
INTRODUCTION
In
a number of laboratories evidence has
been obtained indicating the existence of an as-
yet-unidentif ied channel wherein information
is
coupled from remote electromagnetic stimuli
to
the human nervous system as indicated by physio-
logical
response,
even though overt responses
*
such as verbalizations or key presses provide no
evidence for such information transfer.
Physio-
logical measures have included plethysmographic
response 1 and EEG activity.
Kamiya,
Lindsley,
Pribram,
Silverman,
Walter,
and others have
suggested that a whole range
of EEG responses
such as evoked potentials
(EPs),
spontaneous
EEG,
and the contingent negative variation
(CNV)
might be sensitive indicators
of
the detection
of remote stimuli not mediated by usual sensory
processes. 4
A pilot study was therefore undertaken at
SRI
to determine whether EEG activity could be
used as a reliable indicator of information
transmission between an isolated subject and
a
remote
stimulus.
Following earlier work
of
others,
we assumed that perception could be in-
dicated by such a measure even in the absence
of
verbal or other overt indicators.
To aid in selecting a stimulus,
we noted
that Silverman and Buchsbaum attempted,
without
success,
to detect EP changes in a subject in
response
to a single stroboscopic flash stimu-
lus observed by another subject.
Kamiya sug-
gested that because
of
the unknown temporal
characteristics
of
the information channel,
it
might be more appropriate to use repetitive
bursts of
light
to increase the probability of
detecting information transfer.
Therefore,
*Consultant to SRI.
Menlo Park,
California
94025
in our study we chose to use repetitive light
bursts as stimuli. 7-9
PILOT STUDY AT SRI
In the design of
the study
it was assumed
that
the application of
remote stimuli would
result in responses similar to those obtained
under conditions
of direct stimulation.
For
example,
when normal subjects are stimulated
with a flashing
light,
their EEG typically shows
a decrease
in the amplitude of
the resting
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
putative
sender),
the EEG
of another subject
in
a remote room with no flash present
(a receiver),
w
might show changes in alpha
(8-13 Hz)
activity,
and possibly EEG driving similar to
that of
the
sender,
either by means
of coupling
to
the sen-
der's EEG,
or by coupling directly to the
stimulus.
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 per-
ceived that event,
consciously
or unconsciously,
it might be evident from changes
in his EEG out-
put.
The receiver was seated in a visually
opaque,
acoustically and electrically shielded
double-walled steel room located approximately
7 m from the sender's
room.
We initially worked with four female and
two male volunteer subjects.
These were desig-
nated "receivers.”
The senders were either other
subjects or the experimenters.
We decided be-
forehand to run one or two sessions
of
36 trials
each with each subject
in this selection proce-
dure,
and
to do a more extensive
study with any
subject whose results were positive.
A Grass PS-2 photostimulator placed about
1 m in front
of
the sender was used to present
flash trains
of
s 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
1-120 Hz.
The EEG
data were recorded on magnetic tape with an Am-
pex SP 300 recorder.
On each
trial,
a
tone burst
of fixed fre-
quency was presented to both sender and receiver
and was followed
in one
second by either
a
s
train of flashes or a null flash interval pre-
sented
to the sender.
Thirty-six such trials
were given in an experimental
session,
consisting
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of
12 null trails—no flashes following the
tone—12
trials of flashes at
6 f.p.s*
and 12
trials
of flashes at
16 f.p.s,,
all randomly in-
termixed,
determined by entries from a table of
random numbers*
Each of
the trials consisted of
an 11-s EEC epoch.
The last 4 s of
the epoch
were selected for analysis to minimize the desyn-
chronizing action of
the warning
cue.
This 4-s
segment was subjected to Fourier analysis on a
LINC
8 computer.
Spectrum analyses gave no evidence
of EEC
driving in any receiver,
although in control runs
the receivers did exhibit driving when physically
stimulated with the flashes.
But of
the six sub-
jects studied initially,
one subject showed a
consistent alpha blocking effect.
We therefore
undertook further study with this subject.
Of
our six subjects,
this one had by far the most
monochromatic EEC spectrum.
Figure
1 shows a
typical occipital EEG spectrum of
this subject.
FREQUENCY — Hz
FIGURE
TYPICAL POWER SPECTRUM AVERAGED OVER
TWENTY 8-SECOND EPOCHS
Data from seven sets of 36 trials each were
collected from this subject
on three separate
days.
This comprised all the data collected to
date with this subject under the test conditions
described above.
The alpha band was identified
from average spectra;
then scores of average
power and peak power were obtained from indi-
vidual trials and subjected to statistical anal-
ysis.
The final analysis showed that power
measures were
less in the
16 f.p.s.
case than in
the 0 f.p.s.
in all seven sets of peak power
measures and
in six out
of
seven average power
measures
.
Siegel's two-tailed
t approximation to the
nonparametric randomization test11 was applied
to the data from all
sets,
which included two
sessions in which the sender was removed.
Aver-
age power on trials associated with the occur-
rence of
16 f.p.s.
was significantly less than
when there were no flashes
(t = 2.09,
d.f
= 118,
P < 0.04).
The second measure,
peak power,
was
also significantly less in the 16 f.p.s.
condi-
tions than in the null condition
(t
* 2.16,
d.f.
= 118,
P < 0.03).
The average response
in
the
6 f.p.s.
condition was
in
the same direction
as
that associated with
16 f.p.s.,
but
the ef-
fect was not statistically significant.
As part
of the experimental protocol the
subject was asked to Indicate conscious assess-
ment for each trial as
to which stimulus was
generated.
The guess was registered by the sub-
ject via one-way telegraphic communication.
An
analysis of these guesses has shown them to be
at chance,
indicating the absence
of any supra-
liminal cueing,
so arousal
as evidenced by sig-
nificant alpha blocking occurred only at the
noncognitive level of awareness.
Several control procedures were undertaken
to determine if
these results were produced by
system artifacts or by subtle cueing of
the
subject.
Low level recordings were made from
saline of
12 kCl resistance
in place of
the sub-
ject,
with and without the introduction of
10 Hz,
[jV signals from a battery-operated
generator.
The standard experimental protocol
was adhered to and spectral analysis
of the
results were carried out.
There was no evidence
in the spectra associated with the flash fre-
quencies,
and the
10 Hz signal was not
perturbed.
In another control procedure
a five
foot
pair of leads was draped across
the subject's
chair (subject absent)
,
The leads were con-
nected to a Grass P-5 amplifier via its high
impedance input probe*
The bandwidth was set
0*1 Hz
to 30 kHz with a minimum gain of 200,000.
The output of
the amplifier was connected to
one
input of a C.A.T,
400C "averager."
Two-
second sweeps,
triggered at onset of
the
tone,
were taken once every 13 seconds for approxi-
mately two hours,
for about 550 samples.
No
difference
in noise level between the fore-
period and
the onset
of flicker was observed.
REPLICATION STUDIES AT LANGLEY PORTER
The next effort was directed toward repli-
cation by an independent laboratory of the
original
SRI study of EEG response
to remote
strobelight stimuli.
Arrangements
for replica-
tion were made with the Langley Porter Neuro-
psychiatric
Institute, University of California
Medical Center,
San Francisco*
As a special precaution against the possi-
bility of system artifacts
in the form of elec-
tromagnetic pickup from the strobelight dis-
charge
or associated electronic equipment
(e.g.,
through the power lines),
SRI developed an
entirely battery-operated package for use
as
a
stimulus generator for
the EEG experimentation.
It consists of
a battery-driven Incandescent
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FIGURE 2
SCHEMATIC OF THE REMOTE SENSING EEG EXPERIMENT
lamp, whose CW output passes through
a mechani-
cal chopper continuously driven by
a battery-
driven motor as shown in Figure
2.
A 10-Hz
timing generator (computer triggered) controls
the generation of
a 1-kHz warning tone
two sec
before onset of
the experimental period,
and
also drives
a locking circuit
that determines
the presence or absence of
the ten-sec light
stimuli,
again all battery operated*
Thus
everything on
the left of
the diagram of Fig-
ure 2
is battery operated and therefore inde-
pendent of the power line
system*
Further,
replacement of
the arc-discharge strobelamp by
an incandescent
lamp eliminates the possibility
of direct subliminal pickup of audio or elec-
trical signals
from possible transients associ-
ated with the arc discharge or associated
electronics.
Description of the EEG Processor
A hardware single channel power spectrum
analyzer was constructed from
a commercial band-
pass filter with corner frequencies of 9.0 and
12,0 Hz,
and 48 dB down at 8.0 and 13.0 Hz*
Analog multipliers convert the filter output
to
a signal proportional
to in-band power*
To con-
firm that this system
is equivalent to the stan-
dard FFT analysis used
in the pilot study,
the
analog data of
the pilot study was reanalyzed,
and the result was found to be consistent with
the earlier analysis.
Experimental Protocol
Each experimental session consisted of
trials,
20 each for
the 0
(no light)
and 16
f.p.s,
of
the remote light stimulus.
A
trial
is
defined
as a warning tone followed by
a 10 sec-
ond period consisting of
a
2 second wait,
and
two 4 second data collection periods.
The trial
rate was one trial every 30
±
1 seconds.
The
trial sequence was randomized subject
to
the
following conditions:
(1)
in each group
of
trials
there were equal numbers
of each condi-
tion,
and
(2)
no more than three in a row of
a
single
type were allowed.
Seven 40 trial se-
quences were made according to this prescription
and recorded separately on audio
tape.
During
the session,
trials were generated from one
of
these
tapes and the sequence was unknown to
the
experimenters since the sequence tapes were
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generated one month in advance of
the experi-
ments.
As
in standard EEG protocol,
and
in
accordance with preestablished criteria,
certain
trials were deleted after the session for three
reasons only:
artifact,
logic circuit failure,
or abnormal EEG power.
If
a
trial was rejected,
a trial
of
the opposite stimulus condition was
rejected
at random from
the particular set of 10
trials
in question.
If more than 10 trials of
a given type were rejected from
a session,
the
entire session was deleted.
(This occurred
twice
in each experiment.)
Six channels of EEG and one
logic channel
taken from the sequence tape were recorded on a
multiplexed FM analog tape recorder.
The logic
on the
tape differentiated the trials between
flashing and nonflashing conditions.
In pretesting
the equipment,
we ran
the
experiment using unselected subjects such as
laboratory personnel,
in order
to
test the
adequacy of
the experiment and to determine
whether there were any correlated electronic or
mechanical discharges from the apparatus.
In
20 sessions of data acquisition,
of 40 each (800
trials)
there were no significant differences
between the null and 16 Hz conditions.
RESULTS
Using the above protocol,
two experiments
were conducted during a three-month period.
For
half of
the sessions,
the subject was asked to
press
a button when she
felt the light was
flashing.
For the six sessions
(105 trials each
for the 0 and 16 f.p.s.
conditions when she was
not asked to overtly indicate her feelings about
the light,
there was
a slight decrease of
in-
band EEG power measured over the
left occipital
region of
the brain.
Similarly,
for
the six
sessions
(107 trials each for
the
0 and 16 f.p.s.
conditions) when she was asked
to respond overt-
ly,
there was
this
time
a significant decrease
of in-band EEG power
(p £ 0.037,
using an F
ratio test derived from a two-way analysis
of
variance).
In considering the experiment
as
consisting of
the combined 212 trials
in each
stimulus condition regardless of
the overt re-
sponse contingency, we find
a statistically sig-
nificant decrease
in in-band EEG power
(p <
0.011,
using F ratio test
as
above).
During the second experiment,
three months
later,
a different contingency was added to de-
termine
if
a
"sender” was necessary to produce
the effect we had observed earlier.
For a given
session,
a random procedure
(with equal
trials)
was used to determine
if
a person (called
the
"sender" person) would be looking at the photo-
simulator.
There was no one present with the
photo-stimulator otherwise.
For the
7 "non-
sender" sessions
(121 trials each for the
0 and
f.p.s.
conditions)
we find a statistically
significant increase of
in-band EEG power mea-
sured over the mid-occipital region of
the brain
(p <
0,039 using an F ratio test
as
above).
During the "sender” sessions
(123 trials
in each
stimulus condition)
there was
a slight increase
of in-band EEG power.
All
together,
there was
a
statistically significant increase of in-band EEG
power when the 244 trials were analyzed regard-
less of "sender" condition
(p <
0,008 using an F
ratio test as above),
and there was no signifi-
cant difference found between "sender" /"no-
sender" conditions.
For both experiments,
we considered
in-
band EEG power for the 0-4 second and 4-8 second
time periods independently
to determine
if
the
effects were time dependent.
Although some of
these
isolated sub-intervals were statistically
significant,
no systematic relationship emerged.
Thus
the effect appears
to be cumulative over
the
8 seconds.
The 0-8 second results
are sum-
marized
in Table
1.
Table
SUMMARY OF RESULTS OF THE REPLICATION EXPERIMENTS SHOWING
POWER MEANS AND STATISTICAL RESULTS FOR THE VARIOUS EXPERIMENTAL CONDITIONS
Experiment
I
Experiment
II
Guessing
Sessions
Non-Guessing
Sessions
Combined
Sender
Sessions
Non-Guessing
Sessions
Combined
No light flash
957
704
832
854
766
810
Light flash
873
647
761
860
844
852
F ratio
4.39
2.20
6.47
0.017
4.33
7.03
dV
df
1;
202
1;
198
1;
400
1;
232
1;
228
1;
460
P *
0.037
0.14
0.011
0.90
0.039
0.0083
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DISCUSSION
have been found.
Thus,
although our filter
Although our pilot experiment and the two
replication studies
all showed significant
changes
in EEC production correlated with the
presence or absence of
a remote
light stimulus,
the sign of
the systematic change
in power in
the third study was opposite
to that of
the
first
two.
We
therefore undertook
a detailed
frequency analysis of the EEG data tapes from
the last two experiments,
since
the pilot ex-
periment had already been subjected to fast-
Fourier-transform (FFT)
analysis.
We conjec-
tured that the observed power change
in these
experiments might be
the result of a very small
frequency shift,
which could become translated
into a large amplitude change due to discrimi-
nator action of
the alpha-band filter.
In a
chapter on alpha blocking,
Kool,
in his Funda-
mentals
of Electroencephalography says,
for ex-
ample,
* r
.
.
•
attentiveness
is associated with a
reduction
in amplitude and an increase
in aver-
age frequency of spontaneous cerebral poten-
tials.
.
. The center frequency of
the alpha
rhythm may be Influenced by the type of ongoing
mental activity.
Shifts
in frequency may be
highly consistent
as two different
tasks are
performed alternately. "
The FFT analysis for
the second experiment showed that
the average
peak EEG power occurred most often near 8 Hz,
and
thus fell slightly below the hardware
slim-
ming window
(±3 dB at 8.7-12.4 Hz)
enhancing
a
possible discriminator effect.
The FFT analysis
further showed that there was an overall
in-
crease in frequency of peak power but the shift
was statistically nonsignificant.
This slight
shift of 0.11 Hz could possibly account for the
observed power increase due
to the highly,
non-
linear discriminator effects.
In examining
other portions of
the spectrum for further ef-
fects,
we found that systematic amplitude
changes are highly dependent upon where
in the
frequency spectrum
the power sum
is
taken.
This
is
to be expected since almost all EEG phenomena
are known to be strongly frequency dependent.
In
the pilot study the frequency region for
analysis was centered about the subject’s domi-
nant EEG output frequency with bandpass deter-
mined by the full width ten-percent power points.
In the two replication studies we used hardware
filters
at this same frequency.
FFT analysis,
showed clearly that
if other filter bands had
been chosen,
significant correlations would not
selection was made before
the collection of
any
data,
other experimenters might have reasonably
chosen other criteria for frequency selection.
Therefore,
although we have found statistically
significant evidence for EEG correlates
to re-
mote light flash stimuli,
we consider these data
to be only suggestive, with a definitive result
requiring further experimentation,
REFERENCES
1.
E.
D. Dean,
Int.
J.
of Neuropsychiatry ,
Vol.
2,
p.
439,
1966.
2.
C.
T. Tart,
Int.
J,
of Parapsychology,
Vol.
5,
p.
375,
1963,
3.
T. D. Duane and T.
Behrendt,
Science,
Vol.
150,
p.
367,
1965.
4.
R.
Cavanna, Ed.,
Psi Favorable States
of
Consciousness .
New York:
Parapsychology
Foundation,
1970.
5.
Ibid., pp.
143-169.
6.
Ibid. ,
pp.
158-159.
7.
R. Targ and
H.
Puthoff,
" Information Trans-
mission Under Conditions of Sensory Shield-
's/
1 Nature ,
Vol.
252,
No.
5476,
pp.
602-
607, October .18,
1974.
8.
C. Rebert and A. Turner,
"EEG Spectrum
Analysis Techniques Applied to the Problem
of Psi Phenomena," Physician’s Drug Manual ,
Vol.
5,
Nos.
9-12,
Vol.
6,
Nos.
1-8,
pp.
82-88,
January-December 1974.
9.
H.
Puthoff
and R.
Targ,
"A Perceptual Chan-
nel for Information Transfer Over Kilometer
Distances:
Historical Perspective
and
Recent Research," Proc.
IEEE ,
Vol,
64,
No.
3,
pp.
329-354, March 1976.
10.
D. Hill and G.
Parr, Electroencephalo-
graphy:
A symposium on its Various
Aspects .
New York:
MacMillan,
1963.
11.
S.
Siegel, Nonparametric Statistics for
the Behavior Sciences .
New York:
McGraw-
Hill,
1956,
pp.
152-156.
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