THE

HOSIP HOTRON
smphofl poa~ Phosphene (<Greek: phos, a light + phainein, to show) "a bright
light or visual image produced by stimulation of the retina through
closed eyelids." Phosphotorn (phosphene + electron) "electronic
instrument used to produce phosphenes by passing weak electronic
currents through the eyes ."

s we go through daily life our eyes are open most of the time. During sleep our
eyes remain closed, but often exhibit movements. The visual aspects of these two
contrasting states of consciousness have long intrigued me. Much of the visual
imagery in my video and film compositions is drawn from the substance of images
seen with the eyes closed.
To date no camera has been invented that can directly closed eyes and VERY GENTLY touch the fronts of
record the actual appearances of "closed eye" visual your closed eyelids, very slowly, you can see even
phenomena. Consequently any artist seeking to explore more phosphenes, perhaps brighter colors, more flash-
this visual domain must report backwith constructions ing, or even some very soft forms like chevrons, or
and re-creations of what can be seen with the eyes crosses, or arcs.
closed . There is an infinite number of phosphenes, and no
I invented my Direct Video Synthesizer to have a two seem ever to be exactly alike. The conditions under
means ofreproducing images I have seen with my eyes which you can see them vary considerably, but they are
closed . These images have color, and are almost al- there nonetheless, a distinct reality unto themselves .
ways moving, hence they require a cinematic medium Phosphenes can be stimulated by various methods,
to represent them. some mechanical, like pressing on your eyelids. An-
Almost all visual art requires a screen or surface as a other mechanical source can be a blow to the head, by
carrier ofthe image. For paintings there is the canvas, falling down, or having something fall on top of your
for lithography and photography there is fine paper, for head, or even by being "slugged" by another person .
video there is the cathode ray tube, and for film there is (Boxers are known to "see stars" after being knocked
the "silver screen ." out.)
But I have wanted to eliminate the screen from my Another method of stimulating phosphenes is by
visual art for a long time . I want to be able to produce dark adaptation . Yogis who enter deep, dark caves for
an image right inside your eyes, without the need for extended periods of time can view personal mandalas
you to look at a surface. of phosphenic forms.
The discovery of phosphenes has been for me a step Researchers in outer-space and military fields have
in that direction. I placed volunteer subjects into totally dark chambers for
You have probably seen a phosphene before . When days on end. After a few hours most subjects report
you close your eyes gently and then squeeze them seeing phosphenic activity, often with considerable
tightly for a few seconds, you will notice that you do visual details and brilliant colorings.
not "see" a plain black, empty nothingness. Still another method of stimulating phosphenes is by
Rather you will see some colors washing across your electronic currents . Weak currents can be passed onto
field of view, perhaps some bright flashes or yellow or the retina directly, with no light coming into the eye,
pale blue light. Furthermore, if you now relax your and phosphenes can be produced . Specific visual
 SEND 27

effects can then be produced in the viewer by varying

the current in time . This is the method that my PHOS-
PHOTRON utilizes .
Figure 1 shows a diagram of the human eye in cross
section . Light normally enters the eye through the cor-
nea and iris, which adjusts the amount of light passing
onto the lens. A magnificent set of muscles operate the
lens to focus the image onto the retina . At the retina the
light falls on rods and cones, just two of the sensing
nerves which make up the retina . On the rods and cones
wonderful photochemical and electrochemical effects
convert the light pattern into electrical signals, These
electrical impulses travel up the optic nerve into the
visual portion of the brain, which is only a short dis-
tance behind the eyes .
The locations at which phosphenes originate within
the eye are generally considered to be on the surface of
the retina and at the front of the optic nerve. Exactly
how the phosphenes occur is not understood very well .
One theory is that they are electronic in origin . Me-
chanical pressure on the eye produces photochemical
action on the retina, triggering weak electrical im-
pulses in the nerves .
The electro-chemistry of the retina is quite complex
andincludes many exotic biological substances . One of
these substances is rhodopson. It is present in varying
concentrations, depending on the intensity of light
entering the eye at any given time.
If you are in the dark for some time, say an half-hour
hour, the concentration of rhodopson on the retina
decreases. Rhodopson seems to inhibit phosphene per-
ception, and to upset the conditions required for max-
imum phosphenec activity. As the subjects in dark
chambers become dark-adapted their rhodopson level
decreased and they begin to see phosphenes in copious
amounts.
The Phosphotron instrument I have been using
allows a wide range of visual effects to be produced in
the viewers' eyes. It has been carefully designed and
operated, paying close attention to the safety of the
viewer, and the viewers' total and complete isolation
from any main power sources or earth grounds.
IT IS STRONGLY URGED THAT YOU DO NOT
TRY TO REPRODUCE THE HUMAN CIRCUIT
USED IN MY PHOSPHOTRON UNLESS YOU
KNOW HOW TO ISOLATE THE VIEWER FULLY
AND COMPLETELY FROM ELECTROCUTION!!!
Figure 2 is a schematic of the human circuit funda-
mental to my phosphotron. There is no surgical im-
plantation required . Rather there is a pair of external
electrode discs attached to the viewers' temples, just
behind the corner of the eye . The electrodes are then
connected to a waveform generator with an impedance
matching circuit to optimize the electronic circuit
through the viewer's head . Suitable voltage and current
limiting circuitry is also included to protect the viewer Figure 2
from excessive currents or voltages that could prove
damaging or fatal .
28 Spring 84
Voltage is limited to two volts, and current is limited
to less than 10 microamps . The current limiting is
adjustable to provide for group viewing with viewers
wired in parallel .
Figure 3 shows the group participation version of my
PHOSPHOTRON. It is essentially a parallel circuit of
all the viewers' heads . I first explored this configuration
in 1968 at the University of Illinois in Champaign . This
is the configuration used in the recent revival of the
PHOSPHOTRON at the 1983 San Francisco Interna-
tional Video Festival .
The parallel circuit feeds the same impulses to all
viewers' heads simultaneously . All are presented the
same view together . This configuration is opposite of
the series circuit, where the source signal passes first
through one viewer, then the next, and the next. Series
has the undesirable problem that a much greater volt-
age must be used, and if one viewer removes the elec-
trode set, the circuit is broken, and all others see
nothing.

THE PHOCABULARY
Figure 3
OF PHOSPHENES
When you begin to observe phosphenes you will see
there are many different kinds. Some phosphenes are
simply specks or dots of bright light, usually ruby red
or deep blue, scintillating against a black background .
Others assume more specific forms such as wavy lines
with a vertical, horizontal or diagonal orientation. Still
others are distinctly radial or centripetal in structure
and shape.
The coloring of phosphenes encompasses a wide
,. m m

range of hues and luminosity. After the dark adaptation

JL'
period the first phosphenes observable are usually faint
Vl i_\ S

ce'-~ - fffl
and pale, lacking much color saturation. However, as
dark adaptation increases, and the rhodopson level
decreases, the coloration becomes more vivid, with
pale colors giving way to richer, more saturated colors .
The chart shown in figure 4 is adapted from a joint
research paper by the German Institute for Electronic
Research and the Department of History of Art, Yale
?)llh IIll University, published in 1962. In these experiments
6., Da
J

~F .11 subjects were stimulated with rectangular impulses

applied with frontal electrodes . The pulses were of a
voltage range between 0 .5 and 3 .5 volts, and the ratio
of offon for the pulses was varied .
Q
The horizontal axis of the graph shows the pulse
frequency, while the vertical axis shows the various on-
off ratios used. The researchers then plotted the
>~< 1W sketches of different phosphene patterns reported by
the subjects . The subjects were fully dark adapted be-
fore the experiment began .
The chart shows that most .hosphene activity occurs
SSff
below an excitation frequency of 40 Hz (cycles per
second) . While a few patterns were observed beyond
Figure 4
the 40 Hz frequency, my own experience has shown
that a sudden and abrupt cut-off does occur at 40 Hz.
 SEND 29
The types of phosphene patterns show some correla- from the singularity range to the micropattern range a
tion to pulse frequency and ratio . For example, follow central, pulsing sphere will explode into thousands of
down the 20 Hz line of the chart. At pulse ratios of 1:1 colored bubbles .
there are radial patterns . As the ratio increases (the There is clearly a correlation of this effect with the
pulse becomes narrower) the patterns change to lines, persistence of vision effect that makes cinematic forms
both straight and wavy . At very short pulse ratios of 1 :14 like films and video perceptible as a continuous moving
the pattern becomes radial or star-like. Finally at ratios image instead of separate still images . Persistence of
of 2 :1 or more some radial starbursts appear, and at vision effects begin to occur at 20 Hz and improve at
ratios of 2:6 the patterns become dot or speck-like. higher view-per-second rates.
The sketches on the chart were representative of two For example, video displays 30 frames-per-second.
subjects, and are certainly far from conclusive . My But each frame is split into two field or alternation
experiences with the PHOSPHOTRON in fact support lines, so that the eye is presented 60 views per second .
the types ofphosphene patterns indicated in this chart, Likewise, most film projection occurs at a 24 frames-
but not necessarily at the same frequencies or pulse per-second rate . But a rotating shutter further divides
ratios . each frame into 2 or 3 flashes so that the eye receives 48
My PHOSPHOTRON uses a much wider range of or 72 views per second . The overall effect of thesetech-
impulse waveforms than the German researchers' . I niques is a smoother perception of motion by the
have the generator produce not only square or rec- viewer.
tangular pulses, but also sine waves, triangle waves,
and ramp waves . Each wave gives a different phos- N
phene effect . Furthermore, the PHOSPHOTRON
frequency range is from 1 cycle every 10 seconds to a
maximum of 100 cycles per second . I also have in-
cluded a "sweep" capability to continuously vary the
waveform frequency at rates as fast as 1-40 Hz in 1
second .
Using the two frontal electrodes with the PHOS-
PHOTRON I am able to produce "stereo" sweep visual
effects . By varying the duty cycle the image may be
directed from the left to the right side of the viewer's
field of sight. A balanced drive waveform centers the
images .
With a sine or triangle wave impulse the visual effect
is a "fade in-fade out" with soft, gradual edges . The
triangle waveform produces a brief flash or point of
light at its peaks, The square wave produces the most
dramatic effects : bright flashes with a staccato or punc-
tuatedeffect .
Experiences on the PHOSPHOTRON also lead to
some remarkable frequency-sensitive effects. At low
frequencies from less than 1 Hz to about 20 Hz the phos-
phene image is distinct and singular. Between 20 Hz
and 30 Hz the singularity changes into more of a field
effect, with a single phosphene pattern giving way to
micropatterns . Then between 30 Hz and 40 Hz the
entire field of view explodes with a myriad of detailed
micropatterns .
At frequencies above 40 Hz however, there is a sud-
den and complete blanking of all the phosphene effects .
Perhaps with much higher voltages at the higher fre-
quencies phosphenes can be seen again. But the voltage
required could approach dangerous levels . The shock
at voltages above 4 or 5 Volts DC is very painful, limit-
ing my own exploration of any possible effects in this
range.
The higher frequency patterns are the most interest-
ing from a visual standpoint . Scintillating dots, or
moire patterns, paisley-like forms, brilliant colors, and
much animation all seem to be at a maximum in this
higher frequency range. As the frequency is raised
30 Spring 84

Steve Beck's
PHOSPHOTRON
(with special musical guests Henry Kaiser and Charles E . Noyes)
Presented at the 1983 Ban Francisco International Video Festival
October 6, 1983
THE PERFORMANCE :
I . Prelude for Dark Adaptation
II . Phosphene Fantasia
The PHOSPHOTRON is a 'closed eyes' visual experience .
After you have become dark adapted and are wearing the phosphene headset
your visual field will become filled with pulsating light patterns .

THE PHOSPHOTRON
At first you ill sense dark and light without much coloration . After
about
ab,d 18 m notes more of dark adaptation you shoul begin to see
cc orings . r
we will-. b e flooding your eyes with weak electrical signals in the range
of .1 to 48 cycles per second, using a variety of waveshape patterns . PERFORMANCE
The richness of the phosphene images increases as your eyes become more
dark adapted, so patience is necessary .
Phoephenes originate in the retina and the optic nerve . With your eyes
open the incoming light overpowers the normally weak phosphene patterns . Figure 5 shows the program notes for my recent par-
Experiments have shown that most people will begin to see phosphenes ticipation performance piece presented in San Fran-
after some period of dark adaptation . Subjects enclosed in totally dark
rooms will begin to see brilliant optical images after 1-3 hours . cisco . Each group of guests was limited to nine
Classically, those who enter . deep, dark caves to meditate for long
periods of time will be treated to a marvelously
persons . Each guest was required to sign a release
rich light show of
phospheric images . form, as shown in figure 6.
You may also cause phosphenes by pressing your finger tips VERY GENTLY
on your closed eyelids . I was playing the phosphotron as part of a trio that
Electrically induced phosphenes suggest the possibility of directly
placing a television image into your vision included musicians Henry Kaiser on processed elec-
monitors . The simple techniques used in the without the need for TV
sufficiently refined to this point . PHOSPHOTRON may some day be tronic guitar, and Charles K . Noyes on percussion . The
musicians and myself were also wired into the PHOS-
Steve Beck's PHOTRON, all in a parallel configuration with the
PHOSPHOTRON audience .
(with special musical guest Henry Kaiser)
Presented at the 1983 San Francisco International Video Festival
After bringing the guests in to be seated we first
October 6, 1983 placed the electrode set headbands I had designed on
THE PERFORMANCE :
I . Prelude for Dark Adaptation
II . Phosphene Fantasia
each guest, along with a dab of STIMUGEL electro-
lytic paste to improve conductivity into the skin .
Each performance will be of 45 minutes duration, and can only accomodate
e participants at a time.. The lighting was a subdued red light to help begin the
You will have to sign your name up on the computer for the time you wish
to participate .
dark adaptation process . The PRELUDE included a
Persons subject to heart conditions or epileptic siezures, or who use verbal recitation of the phenomena, then segued into
pacemakers, cannot be permitted to participate .
You will be required to sign a release form before being wired up .
the opening music. Each guest was reminded that they
could easily remove the electrode headset at any time if
Performance times will be :
7 ;45 PM
they began to feel any shock pain. Of course many
8 :3B
9 :15
PH -
PM guests were not at all bothered by the minor shock pain,
18 :88
18 :45
PM
PM similar to a small needle prick, and in fact, some
Please sign up on the computer . seemed to quite relish the sensation.
Unfortunately we had to accelerate the dark adapta-
tion process, and allowed about ten minutes to elapse
Figure 5 before fully beginning the second movement of the per-
formance, the PHOSPHENE FANTASIA . While
some guests reported perception of the effect immedi-
ately, others required several more minutes to begin
seeing the effect .
The highlights of each performance included the
interplay between the musicians and myself, the phos-
phenist. As the music ranged from slow adagios and
subdued modalities, to lively, quick andantes and al-
legro tempos, I could vary the PHOSPHOTRON
frequency and waveform accordingly. Sometimes the
musicians would follow the tempo set by the PHOS-
PHOTRON, other times I would follow their tempo.
Only about five out of the fifty guests did not see any
effects at all . In fact over twenty guests reported quite
vivid phosphenes, especially as dark adaptation im-
proved later in the piece. Guests were freely encour-
aged to describe their perceptions verbally, and many
times several guests simultaneously spoke up about
"the blue lines" or "all those colored dots" .
SEND 31
I purposely limited the duration of each performance ACKNOWLEDGEMENTS
to about thirty minutes . By the end of the evening six In conjunction with the PHOSPHOTRON performance at the San
Francisco International Video Festival I would like to thank my
shows had been given . At that point the musicians and assistants Roger Polk and Henry Spragens for technical support in
myself had been wired for a total of three hours, and mounting the show, and also Donna Steiner for translating my
had incurred minor electrode burns on the temples . sketches into the illustrations for this article .
There were no reported after effects by any, of the I would also like to thank the musicians Henry Kaiser and Charles
guests, K. Noyes for their participation in the performance, and Katie
McGuire for photographic documentaion of the event.
and my vision was not affected even after the total Finally, I must thank the original "guinea pigs" from the 1960's at
accumulated time of exposure . In fact, my own vision Champaign, Illinois, for joining in the earliest experiments I con-
seemed to be sharpened and focused by the currents . ducted, particularly Rob Fisher, Teddy Timreck, Barry Fasman, and
Jim Cuomo.
And last but not least, Steve Agetstein and Wendy Garfield of
SEND magazine who organized the Video Festival and were daring
CONCLUSION enough to ask me to re-present the PHOSPHOTRON.

REFERENCES
The result of the PHOSPHOTRON performance "Design for a Phosphene Visual Prosthesis" E. Marg, J.M .
was to establish a new form of television, an "ultra- Fordemwalt, J. Miner, BRAIN RESEARCH, #19 (1970) . Elsevier
video", beyond video in its current form. Publishing, Amsterdam.
"Effects of Chemical Stimulation of Electrically-Induced Phos-
While we are at the primitive stages of developing phenes on their Bandwidth, Shape, Number and Intensity" M. Knoll,
this visual artform, we know that there is a vocabulary J. Kugler, O. Hofer, S.D . Lawder ; CONFIN NEUROLOGY 23 :
of elements, and can begin to pursue the grammar and 201-226 (1963) . S. Karger, Basil, Switzerland .
syntax of this language. We are at the "dot and dash" "Die Reproduzierbarkeit von elektrisch angeregten Lichterschein-
code level at this point, and many technical problems ungen (Phosephene) bei zwei Versuchspersonen innehalb von 6
Monaten" M. Knoll, O. Hofer, S .D . Lawder, U.M . Lawder . ELEK-
need to be solved to develop the art of phosphenes . TROMEDIZIN band 7/1962, Nr. 4 Institut for Technisce Elektronik
There are other aspects to this research that have der Technischen Hoschule, Munich .
practical and medical significance . For example, a
diagnostic tool could be developed that uses a known
set of phosphene stimulation to develop a standard set 14
of responses for healthy eyes. Then, comparison of a
subject to the standard might prove to reveal latent
problems in the subject's visual system before they
become dangerous. It might also be possible to diag-
nose other aspects of the human organism with the
phosphene stimulation-response measurements .
Another area of research that might prove fruitful is
in aiding the blind to see. A pair of eyeglasses equipped
with microelectronic chips and ultrasonic sensors
could "sweep" the space around a person, and develop
a waveform to place bright phosphenes in the location
ofobstacles or hazards. Much work needs to be done to
determine if various forms of blindness can respond to
electronically induced phosphenes . State of the art
research conducted at the University of Utah is cur-
rently involved in placing electrodes directly into the
brain, which requires a surgical operation. An external
set of electrodes that stimulates phosphenes would be
safer than surgery, and less costly, making it more
readily affordable by sightless persons .
Finally, there is the long-term goal of making a phos-
phenic form oftelevision . Can we develop enough pre-
cision in the stimulation waveform to produce a
specific, photographic image in the viewer? If so we
might be able to eliminate the screen from television
entirely .
These questions and others remain to be answered by
dedicated researchers in the life sciences . Just as artists
were the catalyst in developing photography, I hope
that my simple experiments in the visual art of phos-
phenes may lead to future developments beneficial to
humanity . 1-1