CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
EFFECTS OF LSD ON A VISUAL DISCRIMINATION
BETWEEN REAL AND ILLUSORY STIMULI
BY t,1/\CACA t1ULATTA .
A thesis submitted in partial satisfaction of the
requirements for the degree of Master of Arts in
Psychology
by
Paulene Bunker Popek
..-/.
January, 1976
1.(•!'
.... -r- ·-···-··-···-· _..
....
,.
·-·
...
---··--···-·---------------------
'
_'-·;._
/
I
The thesis of Paulene Bunker Popek is approved:
"''
l
(!
California State University, Northridge
December, 197 5
ii
ACKNOWLEDGEMENTS
I would like to thank Ron Siegel who generously provided his
support not only in terms of access to his lab, but also in his personal adv·isory role in my research.
I would also like to thank Dr.
Griffiths for his encouragement in my thesis project and friendship
during my studies at Valley State, and to Dr. Wilsoncroft for his
thoughtful comments and suggestions.
Finally, a great deal of thanks
goes to my husband for his editorial comments, computer assistance,
and understanding patience.
iii
TABLE OF CONTENTS
Page
Acknowledgements
iii
List of Figures
v
List of Tables
vi
Abstract
vii
Introduction
1
Method
15
Results
24
Discussion
40
References
47
iv
LIST OF FIGURES
Page
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Visual angles of the eye at which the
i 11 usory M&t~ is effective
17
One angle of reflection of an M&M inside
the parabolic mirror
18
Cross section of both parabolic mirrors,
one with a real M&M and the other with an
image of a real M&M
19
A series of trials presented on nondrug
days for each group of monkeys
21
Mean discrimination ratio (percentages)
for individual animals in the first ten
sessions and monthly retraining sessions
25
Mean latency (seconds) for individual
animals in the first ten sessions and
monthly retraining sessions
27
Mean discrimination ratio for individual
animals as a function of LSD dose
31
Mean latency for individual animals as
a function of LSD dose
32
Fig. 9 ·Mean discrimination ratio for each drug
treatment averaged across all animals
35
Fig. 10 Mean latency for each drug treatment
averaged across all animals
36
v
LIST OF TABLES
Page
Table l
Analysis of Variance Summary Table
30
Table 2
Number of Uncompleted Trials
34
Table 3
Dunn•s Multiple Comparison Test
39
vi
ABSTRACT
EFFECTS OF LSD ON A VISUAL DISCRIMINATION
BETWEEN REAL AND ILLUSORY STIMULI
BY MUCACA MULATTA
by
Paulene Bunker Popek
Master of Arts in Psychology
JANUARY 1976
Four rhesus monkeys were trained on a simultaneous visual discrimination between a real
(illusory stimuli).
"~1&1''1"
candy and a 3-D projection of a "M&W
Two animals were reinforced for responses made
only to the real, red M&M (color relevant group) and the other two
animals were reinforced for responses made only to the real M&M, irrespective of color (reality relevant group).
Following acquisition
of the task, probe trials (trials in which color was irrelevant) were
ra.ndomly presented among the regular sessions to ascertain which cue,
color or reality, the animals were responding to.
Initial· probe tests
. revealed that monkeys trained with color relevant and reality irrelevant were impaired in accuracy when color was removed whereas monkeys
trained with reality relevant were unimpaired by changes in color.
After several days of probe tests, however, both groups were able to
vii
discriminate on the basis of reality.
Therefore further drug analyses
treated all animals as one group.
Two hallucinogens, lysergic acid diethylamide (LSD), and dimethyltryptamine (Dt:H), both knovm to cause hallucinogenic effects, i.e.,
perceptual changes, were then administered in an attempt to disrupt
previous accurate di scrimi nations between the real and illusory stimuli. i
Other drugs, chlorpromazine (CPZ) and caffeine (CAF), which do not
normally produce hallucinatinns in man, were also administered.
The
accuracy of performance for both groups was impaired (discrimination
ratios
<
50% and latency
>
30 seconds) following the administration of
the highest dose (128 meg/kg)* of LSD.
A dose of 2 mg/kg of DMT, com-
parable to doses of 16 and 32 meg/kg of LSD, also disrupted performance
on both measures, although not so dramatically.
performance latency but not accuracy.
CPZ and CAF disrupted
These results suggest that
hallucinogens produce changes in reality perceptions, i.e., perceptions
betv1een real and illusory stimuli.
*The abbreviation meg is used for microgram.
viii
1
i
INTRODUCTION
Hallucinogens have traditionally been defined as those drugs which
produce hallucinations.
The word hallucination, in turn, comes from the
Latin deponent alucinari, meaning
11
to wander in mind
that drugs produce a Wandering in mind
11
active agents qualify as hallucinogens.
11
,
11
•
To the extent
many, if not most, psycho'""
However, in both pharmacolog-
ical and psychological usage, hallucinogens are those drugs which
produce changes in mood, thought, and perception and are further characterized by the presence of sensory distortions, illusions, or perceptions without objects (hallucinations) (Hoffer and Osmond, 1971).
In
man, where many behaviors are chiefly mediated by the visual modality,
such changes include blurred vision, increased mental imagery, spatial
distortions, object movements, color changes, illusions, and hallucinations.
Many examples in the literature can be found to illustrate
these changes.
ing ketamine
For example, the behavior of preverbal children follow-
~hemically
frequently involves:
related to hallucinogenic drugs) anesthesia
pointing; grasping at the air; spontaneous moving
bf the head and eyes without apparent stimuli, and apparent attempts to
escape.
In one case, while screaming and crying, a child appeared to
strike with his hands at something in the air while trying to crawl
away from an area of his bed (Siegel, Lebowitz, and Jarvik, unpublished).
Similarly, in infrahuman species, where vision is also inferred to be
the primary sensory modality, hallucinogen-induced behaviors are often
11
characterized by Stimul us-specific
11
behaviors which are normally
emitted only in the presence of specific cues but in a drug state are
1
2
often emitted in the absence of such cues.
For example, Samson, a
chimpanzee, was given 30 meg/kg of LSD and reacted in a manner similar
to the child following ketamine anesthesia.
The animal stared into
space with his mouth open, screamed, and leaped backward while striking
at the air with both hands (Baldwin, Lewis and Bach, 1959).
In many of the experiments done with hallucinogens, emphasis on
the action of the drug has been primarily concerned with three behaviors.
First, normal stimulus control (responses controlled by that
particular stimulus) appears to be disrupted in animals (Dykstra and
Appel, 1974) and recognition and recall of stimuli is impaired in man
(Jarvik, Abramson, and Hirsch, 1955).
Secondly, attention to stimuli
seems to "wander", as when human subjects gradually shift their attention from outward dimensions to inner private events (Fischer, 1974),
or as animals shift attention from relevant cues to irrelevant cue
dimensions, as suggested by Sharpe, Otis, and Schusterman (1967).
Third, motor patterns that attempt to consensually validate 11 perceptions
without objects" have been observed in human subjects (Fischer, 1971)
and animals (Lagutina, Laricheva, Mil Shtein and Norkina, 1964).
1
Taken
together, these studies indicate that hallucinogens do indeed
dramatically alter stimulus control, attention, and motor patterns.
Several laboratory experiments therefore have attempted to identify
and further define these and other actions of hallucinogens.
Siegel
(1969) reports disruption of stimulus control in pigeons given high
doses of either LSD or Cannabis (marihuana).
Four pigeons were trained
on a visual discrimination task involving both color and form dimensions.
The birds were put into an operant chamber which had three
3
response keys.
stimuli:
The center key projected three different types of
forms, colors, and a white triangle (standard).
If the
standard occurred the animal was required to respond to the center key
for reinforcement.
If a form occurred, resppnses to the left key were
reinforced and if a color occurred responses to the right key were
reinforced.
Since the stimuli within each group were changed from
tria 1 to tria 1, the birds were required to learn concepts of form
11
change
11
change
11
(the presentation of different types of forms) and Color
11
•
First, stable rates of responding were obtained on the dis-
crimination task followed by the administration of high doses of both
Cannabis and LSD.
Both LSD and Cannabis increased the number of re-
sponses made on the color key when no color changes were actually
occurring.
High doses of LSD also produced a decrement in discrimina-
tion performance not found with comparable doses of Cannabis.
Although
a breakdown in stimulus control is an obvious explanation for the effect
of high doses of LSD, this interpretation does not explain the accuracy
of performance found with Cannabis.
Furthermore, it is also difficult
to explain the decrement in accuracy with no increase in color responding with pentobarbital (a drug which usually impairs stimulus
control).
Another.interpretation offered was the possibility that the
animals were reporting
11
11
perceptual events (i.e., color changes when
no color changes were in fact occurring).
Fuster (1959), using LSD in monkeys, also reported disruptive
effects on a visual discrimination between a pair of objects pres~nted
tachistoscopically for 20 msec.
Monkeys were trained to press a lever
associated with one of the objects to obtain food reward.
With doses
4
between 2 and 8 meg/kg, the per cent correct responses decreased and
the mean reaction time increased.
Fuster concluded that the disruption
of attentional processes was caused by the inhibitory action of LSD onthe central nervous system.
However, because Fuster•s experimental design confounded attention,
latency and accuracy, it becomes difficult to conclude that attention
was the only dimension affected.
Sharpe et al., (1967) attempted to
control the latter two variables in the following way.
They trained
squirrel monkeys to displace one of two vertically presented circular
black discs, differing only in size, in order to obtain a reward.
Re-
sponses were reinforced whenever they occurred within the trial time.
In this design,the variables associated with tachistoscopic responding,
namely accuracy with too brief exposure of the stimulus, are controlled.
The results showed that low doses (0.1 mg/kg to 0.4 mg/kg) of LSD
disrupted performance on the difficult task (size ratio 1.12:1) but not
on the easy task (size ratio 1.96:1) suggesting to Sharpe et al., (1967)
that a shift of attention to irrelevant dimensions (e.g., color) during
the difficult task had taken place.
Therefore, because the animals
responded on both the easy and difficult task, with accuracy failing
only on the latter, attention not motor responding was the disrupted
behavior.
Using a visual avoidance discrimination task with rhesus monkeys,
Brown and Bass (1967) found significant differences among various
classes of drugs.
Monkeys were conditioned to respond to a series of
different sized letter
11
E11 (e.g.,[
,E
,E ). Six of the stimuli
were all varying percentages smaller than the constant test stimulus.
5
A trial presentation consisted of two constant stimuli and one test
stimulus.
The animal was required to select the test stimulus.
If the
animal responded incorrectly or did not respond within 30 seconds, a
5-second shock was given, which could be terminated by a correct response.
After two weeks of 11 error-free 11 performance, the monkeys were
given a variety of stimulant and depressant drugs.
One of the drugs,
LSD, was given in 5 different dosages ranging from .005 to 0.1 mg/kg
ahd found to significantly increase reaction time (latency) on the task.
Reaction time was not found to be dose dependent, although this lack of
significance could have been caused by animal variability.
The LSD
effect on accuracy, on the other hand, did produce a dose-dependent
effect.
Other drugs, such as chlorpromazine, appear to exhibit a con-
verse effect.
At doses of 0.5 to 0.03 mg/kg, chlorpromazine adminis-
tration produced variable changes in reaction time with no disruption in error responding (accuracy) except at the highest dose.
In
general, the results from all the drugs indicate that increasing doses
tend to intensify whatever effect is observed; that is, drug effects
appear to be quantitatively stimulus dependent, although not always in
a linear manner.
Unfortunately Brown and Bass did not include a com-
plete analysis of the accuracy and latency scores or attempt to evaluate the results in terms of drug action on behavior.
Roberts and Bradley (1967) studied the effects of various drugs on
the performance of monkeys in a delayed, successive discrimination task
in an attempt to detect similarities between the effects of drug
administration and the behavioral effects that result from the varying
of motivation and attention.
Animals were overfed and underfed to
6
of performance but manipulation of motivational levels had no effect.
In the same study, high doses of LSD (15 meg/kg) produced increased respending and disruption of accuracy, at delay periods longer than 3
seconds.
That is, the LSD effects were similar to those resulting from
distractive stimuli. suggesting that an attentional shift had taken
place rather than any significant motivational disruption.
However, it is well known that some drugs (especially LSD) often
cause nausea and as a result influence food intake.
Therefore it is
possible that the motivational effects Roberts and Bradley manipulated
in the previous study cannot be compared to LSD effects.
digm
~mployed
Another para-
by Ferraro (1972) which avoids this difficulty, tested
attention using a delayed task.
Monkeys were taught to perform a de-
layed matching-to-sample problem in order to test motor responding,
attention, and memory under THC (tetrahydrocannabinol, the major hallucinogenic prinicple in marihuana).
In those tests, monkeys were cap-
able of matching the sample stimuli to the choice stimuli when little
or no time delay was involved.
mance was disrupted.
At longer time delays, however, perfor-
These results demonstrated that animals had the
ability, motivation, and attention to perform the task under THC with
no delays, but at longer delays (5,
10~
and 20 sec) attention and/or
short-term memory were affected by the same dose of THC.
In general, these studies, as well as others, have shown that hallucinogens impair accuracy (Jarvik and Chorover, 1955; Becker, 1967;
Blough, 1957); disrupt stimulus control (Fuster, 1959; Siegel, 1969);
i
7
and produce attentional shifts (Roberts and Bradley, 1967; Ferraro,
1972; Sharpe et al., 1967).
However, these investigations have failed
to provide an adequate assessment of the perceptual events which specifically characterize hallucinogenic effects or specify the stimulus
control nature of the attentional shifts.
For example, the experiments
do not indicate whether hallucinogens alter the discrimination between
perceptions involving real objects and perceptions involving nonreal
objects, an important characteristic of-psychotomimetic states.
addition, most LSD studies have used limited dose levels.
In
Therefore
the results typicilly indicate that hallucinogenic effects are all or
none; the animal either does not show impairment or is incapable of
motor responses in the task.
While most of
the~e ~esults
are undoubt-
edly due to a failure to establish proper dose-response curves in the
specific task, it is possible that the discrimination employed is not
sensitive to hallucinogenic effects.
That is, while an hallucinogenic-
treated animal may have difficulty in discriminating between two objects
and therefore perform poorly, the use of an accuracy measure unfortunately does not tell the experimenter in what way the animal is unable
perceptually to identify the correct stimuli.
The stimuli may have
taken on other characteristics, such as appearing as if it were not
there, or it may simply be difficult for the animal to attend to the
stimuli in order to make the correct response due to attentional shifts
or distractive stimuli (Roberts and Bradiey, 1967).
In addition, the
clinical literature on psychotomimetic states suggests that researchers
have not used those stimulus dimensions which are most often reported
to be changed in man.
Animal models, therefore, may provide further
understanding to the stimulus controlling variables in drug states.
8
There is evidence that animals, when given LSD, do indeed react to
something, as in the case of Sampson staring into space and striking at
the air.
It is unfortunate that animals cannot verbally communicate
what exactly is being perceived to cause such reactions.
On the other
hand, since animals are verbally noncommunicative, their behavioral
reactions, such as fear responses or striking at the air, give the experimenter added information when analyzing hallucinogenic-treated
behavior.
hallucinations in animals therefore depend on
Drug~induced
what one is willing to infer from the observed behaviors.
Both animals
and man in hallucinogenic states have been observed to react at something which is not there, displaying difficulty in the discrimination
between real and nonreal (or imaginary or illusory) stimuli.
This
impaired discrimination is often referred to as impaired judgement or
faulty
11
reality testing
11
•
For example, both LSD users and schizophre-
nics manifested impaired reality judgement by reporting that some
images perceived during hallucinations were as believable or real to
them as real objects (Aggernaes, 1971).
It is possible therefore, that
animals given hallucinogenic drugs would not be able correctly to
identify a real object from a nonreal object.
Another way to ask the question of what hallucinogenic-treated
animals perceive is to use a discrimination task between real and
nonreal stimuli (e.g., between real stimuli and imaginary or illusory
stimuli).
For instance, discussed above was the idea that hallucino-
gens might alter perceptions with objects and perceptions without real
objects, an important characteristic of psychotomimetic states.
In
this case, real stimuli could correspond to perceptions of real objects
9
·and nonreal stimuli could correspond to perceptions o.f illusory objects.
1
'·
The development of an experimental designthat would involvevisual
illusions, wherein it is possfble to induce perceptions in a subject
(whether animal or man) that cannot be distinguished from images of his
imagination, would therefore allow an operant evaluation of reality
testing.
A reality test, for example, could involve the simultaneous
presentation of an illusory and real stimulus wherein both are visually;
identical but only one being physically present:
This type of design
..i
would allow the interaction between perception and motor response on
i
the part of the animal to be studied.
I
i
I
Webster s Dictionary (1971) defines an illusion as the
1
11
perception
of something objectively existing in such a way as to cause misinterpretations of its actual nature. 11
If an illusory (nonreal) stimulus
and a corresponding real stimulus wer.e put next to each other they
would, at first glance, look alike.
However, upon closer examination
the illusory stimulus would differ in many dimensions.
These
dimen~
sions, including vivacity, coherence, voluntariness, concreteness, and
veridicality, are identical to those dimensions which distinguish experiences such as dreams, thought, hallucinations, perceptions,
tions,
~nd
fantasies (Savage, 1975).
sensa~
A number of studies with animals
have attempted to employ these relatively subtle differences as a basis
for discrimination tasks.
Revesy (1924) was one of the first to experiment with animal
illusions when he trained hens to attend to the larger of two objects
and then introduced an area illusion making the upper object appear
further away from the hen than the lower object, thus producing a
judgement of the actual size of the two objects.
mis~
The hens were able
10
to learn correctly to identify the sma 11 er object.
Several other ex-
perimenters have reported similar results with the Muller-Lyer illusion
with the ring dove (Warden and Baar, 1929); with chicks (Winslow, 1933);
and with pigeons (Malott, Malott and Pokrzywinski, 1967).
Domingues (1954) studied illusions in three different primates.
She trained rhesus, mangabey and cebus monkeys to discriminate among
three types of illusions:
rectangular illusions, vertical illusions
and horizontal illusions.
In a 11 cases, the monkeys were trained
always to respond to the smaller of two objects.
The positive stimulus
in the rectangular illusion always stayed the same size, e.g., 40x90
mm, while the width of the negative stimulus varied, e.g., 60x90 mm,
etc.
The illusion test consisted of the same positive stimulus
(40x90) paired with rectangles that varied in length (30x45 or 30x70,
etc.).
A similar design was followed when presenting vertical and
horizontal lines.
During training, the animals were taught to focus
on width, but during the test the relevant dimension was changed to
length.
Animal perceptions were similar to human perceptions in re-
sponding to some of the geometric figures in a systematically inaccurate fashion.
Harris (1968) replicated part of Domingues rectangular
study but instead of using the same test stimuli, the stimuli were
changed on each trial.
The results were comparable with those of
Domingues.
Angularity distortion, another type of perceptual illusion, has
been studied by Lyon and Thomas (1968).
Pigeons were trained to peck
at a vertical line (90°) in a darkened Skinner box.
Generalization
tests during extinction were performed with the floor of the chamber
11
tilted 0°, 12°, 24° and 36° counterclockwise, each tilt corresponding
to one group.
Five stimuli were presented at different angle orienta-
tions (30°, 60°, goo [cs], 120° and 150°).
Anima·ls tested on a tilt of
0° continued to respond to the vertical line (goo), however animals
tested on the other angles showed enhanced responding to the 120°
stimulus.
The greater the floor distortion, the greater the responding
to the 120° value.
These tests demonstrate that perceptions can be
distorted by altering postural and muscle feedback cues.
Similar experiments involving vertical and postural cues have also
been performed with monkeys (Reid, Medin, and Davis, lg65).
Six
monkeys were trained to discriminate between two simultaneously
presented cylinders.
One cylinder was cut so that it was at a 70°
angle tilted with respect to the apparatus and vertical axis of the
subject and the other cylinder (goo) was vertical with respect to both
the vertical axis of the subject and the apparatus.
During the test
phase of the experiment, the apparatus was tilted at an angle of 20°
with the floor, causing the goo cylinder to become vertical with respect
to the apparatus but tilted with respect to the vertical axis of the
subject, and the 70° cylinder was tilted with respect to the apparatus ·
but vertical with respect to the vertical axis of the subject, thus
producing conflicting visual and postural cues.
The monkeys responded
to the goo cylinder for a series of trials then shifted to the other
cylinder.
This uncertain response pattern indicates a confusion be-
tween visual and postural cues.
In the second part of the study, both
cylinders were equally positioned with respect to the apparatus but
one of the stimuli was vertical and the other was tilted 50° with
respect to the vertical axis of the subject, eliminating all relevant
12
visual cues.
With no obvious visual cues of the vertical, the animals
chose the cylinder that was parallel to their body axis.
These results
are similar to human reports of perceptual distortions when postural or
postural and visual cues are eliminated.
Experiments involving angularity or spatial distortions can be
considered as one type of perceptua 1 i 11 us ion.
However, there are
other types of illusions which involve the presentation of a real-like
stimulus that appears real but in reality is only an illusion of a real
stimulus.
One such way to present such an illusory stimulus is by pro-
jecting a holographic picture, a
using laser beams.
3-dimensio~al
display of an object by
Holograms produce an effective illusion, and are
not inordinately complex or expensive to employ in an experimental
setting.
However, accurate, flexible color reproduction is not possible
due to technical limitations.
A cheaper, easier but still effective
way of producing an illusion is to project a mirror image of an object
of interest using a parabolic mirror.
commercially available.
Recently such a device became
The concave interior of the device is silvered,
producing a mirror, so that when an object is placed in the bottom, an
image of the object appears at a small opening at the top surface.
(See Methods Section for a description of this device.)
Upon presenta-
tion of this device to humans or monkeys, their immediate response has
been to reach for the object, but the hand will go through the projection.
The advantage of this particular method of illusion projection
is that any object, irrespective of color and shape, can be placed at
the bottom and a corresponding image seen at the top.
An animal or per-
son can a 1so easily verify whether or not the image is rea 1 by touching
or not touching it.
Most important, the illusion appears real and
13
.I
convincing.
The illusion used in the present study was designed to investigate
another aspect of the action of hallucinogens on a simultaneous twochoice visual
di~crimination.
This particular design has enable a
comparison of LSD-induced hallucinations and visual illusion, both of
which are reported to vary along similar dimensions, e.g., color, shape,
brightness, vividness and size (Hoffer and Osmond, 1971).
It is
al~o
likely that under the influence of hallucinogenic drugs, the ability to·
discriminate the real from the nonreal wduld be impaired because of
perceptual changes that are reported to occur.
d i sc.rimi nation between a rea 1 candy
~~~~&W
the~
The task involves a
and an i 11 uso.ry
"r~&M"
(a pro- :
jected mirror image) .. Pilot data suggested that the task would be
difficult to learn due to the remarkably convincing projection of the
illusory stimulus.
Therefore two different groups of animals were
trained on each dimension.
One group was trained on a color dimension
and the other on a reality dimension.
It was expected that since the
color group was trained on the more salient dimension (namely color) of
the task and given only irrelevant cues (cues that are not reinforced)
about the illusory dimension, trials to criterion would be less for
this group than for the reality group.
Another important aspect of this task is whether both relevant
cues (cues that are reinforced) and irrelevant cues are learned in a
discrimination problem.
There exists considerable controversy in the
literature concerning this issue.
On position argues is that learning
gradually occurs on both the relevant and irrelevant dimensions that
are used in training (Spence, 1936; Hull, 1943).
Another position
14
(Lashley~
1929; Krechevsy, 1932; Sutherland and Mackintosh, 1971)
maintains that learning involves solving the task using various strategies, thereby often ignoring irrelevant cues.
The findings of the
present study can be applied to these theories by reversing the reinforcement contigencies of the M&Ms.
In this way, if the color group
learned only the relevant, color dimension, the animals should respond
to both the illusory and real, red M&f1 •. The reality group, on the other
hand, should not be affected by the reversed condition and continue to
respond to the real M&M.
This design therefore is unique in that it
will allow hallucinogens to be examined more closely and at the same
time contribute to our understanding of the role of relevant and irrelevant cues in the learning of a new type of iliusion discrimination.
!
t~ETHOD
Subjects
Four female, rhesus monkeys (Macaca mulatta) approximately six
months old (2.4-3.2 kg) at the beginning of the study were used.
They
were housed individually, and had ad 1 ib access to water.
Apparatus
In the present study, a commercially made parabolic mirror called
"Illusion"
(f~anufactured
by t·1oon Lite and Co., Culver City, California), 1
was used to produce an image of one of the stimulus objects.
The
equipment was arranged so that the two concave parabolic mirrors were
placed adjacent to one another inside a sliding black, plastic tray
49.1 em x 27.6 em.
Each mirror could be taken apart (i.e.; for cleaning
purposes) by removing the top half.
The lid of the tray contained two
6.35 em diameter holes located over the respective centers of each
parabolic mirror.
A sheet
~f
glass, placed under the lid, covered'the
holes from underneath, providing depressions on top of the tray when
the lid was closed.
The tray, attached to a small table, could be
pushed out so that the center of each well was within reach of the
animal.
A switch was attached to the metal track of the tray which
automatically triggered the clock to start when the tray was pushed
out within reach of the animal and automatically stopped when the tray
was pulled in.
The clock could be reset after each trial.
A one-way
screen, attached to the length of the table, prevented the animal from
visual contact with the experimenter.
15
The monkey v1as placed 30.5 em
16
away from the center of the two wells at a visual angle of 30°.
The
visual angle was determined by measuring the angle of a straight line
from the eye of a human observer, positioned at the same angle as the
monkey, to the center of one well (Fig. l).
The illusion was effective
at visual angles between 20° and 65° for human (and animal) observers.
The
mirro~
is constructed so that when the stimulus was centered at the
bottom of the well, the image was reflected against several points
within the mirror projecting an image over the respective center of the
parabola (Fig. 2).
During a discrimination trial, one stimulus Was
placed at the bottom of the well (producing an image at the top) and
one stimulus was
(Fig. 3).
~laced
on top of the depression of the other well
A 25-watt bulb, centered between the two wells, was placed
39 em above the tray.
Procedure
Each monkey vJas taken from the home cage and placed in a restraining chair allowing free arm movement and taken to the experimental room.
Fruit was given to each monkey immediately after the
training session in the experimental room.
cage after the last monkey was returned.
Food was given in the home
The amount of food given was
regulated to insure that the monkeys were motivated to consume reinforcements on all twenty trials.
The restraining chair was placed in a sound and light attenuated
chamber (Industrial Acoustics Co., Model 1202-A) where the experiment
was performed.
The chair vJas fastened securely to the floor with the
monkey facing a one-way screen.
A switch inside the chamber controlled
17
I
I
I
I
I
Limits of
effectiveness
/
/
I
/
60°
I
I
/
/
/
/
/
/
Parabolic
t·1i rror
Fig. 1
Visual angles of the eye at which
the illusion is effective
/
/
/
I
18
I
I
I
I
I
I
I
I
Parabolic
t~i rror
I
1~&~1
I
I
I
\.
I
'<
I
I
/
I
1/
Fig. 2
One angle of reflection of an M&M
inside the parabolic mirror
19
Parabolic
r~i rror
Tray
Fig. 3
Cross section of both parabolic mirrors, one with a real
M&M and the other with an image of a real M&M
20
the lights, timing clock and ventilation fan.
The experimenter, sitting
behind the s-creen, was able to observe all behaviors of the monkey and
was able to record trial accuracy and latency.
commercially acquired M&Ms were available:
Six di.fferent colors of
red, orange, yellow, tan,
brown, and green, and were presented in random order with each color
presented an equal number of. times during a session.
were changed daily.
Color sequences
Location of the positive stimulus was randomized
according to a Gellerman series.
Animals were individually shaped to take fruit from one well of
the tray followed by the introduction of an M&M.
tion of the M&Ms then began.
discrimination.
Simultaneous presenta-
Two separate groups were trained on the
Group 1 or the color group, was trained on a color
dimension so that reinforcement was given for responding to the real,
red M&M.
On all trials presented to the color group, the real M&M was
always red, paired with an illusory M&M which was any
colo~
but red.·
The reinforcement consisted of allowing the animal to grasp the M&M and
eat it.
Group 2 or the reality group, was always reinforced for 0e-
sponding to the real M&M irrespective of color.
All trials for the
reality group consisted of the presentation of one real
illusory
~1M1,
both of different colors.
i~&~l
and one
Figure 4 illustrates a series
of trials that could appear for each group.
A daily training session for each animal consisted of 20 trials,
and 5 sessions were given each week.
Latencies were measured by a l/100
second stop clock from the time the tray was in front of the animal
until either well was touched.
Real M&Ms picked up but not eaten were
recorded as correct responses.
A noncorrection procedure was used. ·A
trial was terminated if the animal did not respond within 100 seconds.
21
COLOR GROUP
REALITY GROUP
Trial l
Tria 1 2
Trial 3
Trial 4
sTrial 5
sFig. 4
A series of trials presented on nondrug
days for each group of monkeys
22
Following acquisition, two probe trials (trials in which color was
irrelevant) were presented interspersed among eighteen regular trials.
I
Probe trials were given to determine exactly what the animal had learned:
It
was not known if both groups had learned both col or and reality cues,!
therefore only two probe trials were randomly presented so as not to
reinforce learning on the reality dimension which could be salient
pt'obe testing.
(Probe trials will be represented as follows:
.-
duri~,
I=
illusory, _8_=real, Y=yellov.J, O=orange, B=brov.m, T=tan, G=green, R=red,
and matched-pairs=matched for color so that both M&Ms were of the same
color, i.e., lR paired
~vith
RR.
presentation of probe trials,
In Session ll, the first day for
Grou~
l received an IR paired with RG
(first probe} and IR paired with RB (second probe).
Group 2 received
matched-pairs of red (first probe) and matched-pairs of green (secohd
probe).
In Session 12 and 13 Group 1 received (on both probe trials)
matched-pairs of red.
Group 2 in Session 12 received matched-pairs of
orange (first probe) and brown (second probe}.
probes for Group 2 were illusory.
In Session 13, both
For example, on the first probe, IO
was pa i red with lG and on the second probe, lB was paired with lY.
Session 14 both groups received all real
RB
(first probe) and a
~1M~s,
i.e.,
In
RR paired with a
RR paired with a RY (second probe). Saline was
injected ten minutes prior to the beginning of Session 15, and four
probe trials of matched-pairs of red were presenterl.
Probe trials given
after acquisition involved variations in reversing color and reality
cues in order to test the amount learned on each dimension.
trials given during drug sessions, however, were always
Probe
matched~pairs
of red for both groups.
Drug sessions were then given once a week.
Retraining sessions
23
were given between drug sessions.
Two hallucinogens, lysergic-acid
diethylamide (LSD) and dimethyltryptamine (DMT) were used in the study.
LSD was chosen as the prototypic hallucinogen and DMT was chosen because of its short duration of action.
A stimulant, caffeine (CAF), a ,
phenothiazine, chlorpromazine (CPZ), and saline (vehicle control) were
also used.
The six doses of LSD administered were:
and 128 meg/kg.
1, 8, 16, 32, 64,
DMT and CPZ wereadministered in two doses each:
1 and 2 mg/kg, and CPZ, 0.5 and 0.1 mg/kg.
dose of 10 mg/kg.
DMT,
CAF was administered at a
DMT, CPZ, and CAF were administered in limited doses i
for comparative purposes only.
Drugs were administered
intr~muscularly
into the posterior thigh
muscle and preceeded testing by 10 minutes, the single exception was
with DMT which preceeded testing by 5 minutes (Siegel, Brewster, and
Jarvik, 1974).
During the pretest interval, animal
observed by the experimenter.
behavi~rs
were
Behaviors other than those normally
observed on nondrug days were recorded.
RESULTS
Two behavioral measures, discrimination ratio (DR) and latency,
were used in the analysis.
The DR was defined as the percentage of
-total responses made to the correct stimulus.
daily DRs were calculated for each animal.
Based on twenty trials,
During drug administration,
a total of eighteen trials (probe trials were excluded) were used in
calculating ratios for the sessions.
In all cases, a trial was scored
as correct if the animal chose the real M&M and incorrect if the animal
chose the illusory one. ·Cases in which animals did not respond within
an allotted time of 100 seconds were considered incorrect responses.
Such cases were virtually absent during nondrug sessions.
with this scoring procedure, DRs could fall below 50
Note that
pe~ent.
Latency, the second measure used in the analysis, was determined
for each trial by the elapsed time between stimulus presentation and
response, or when a trial was terminated as a result of no response.
A cutoff value of 100 seconds was used when the animal failed to respond.
Scores from the two probe trials in drug sessions were not
included in either mean DR or mean latency for a particular drug, thus
accounting for the eighteen trials used to compute the DR and latency
for drug sessions.
Probe trials were analyzed separately.
DRs for acquisition sessions andretraining sessions are presented
in Fig. 5.
Data for Group 1 (animals R-1 and R-2) appear in the upper·
graph and data for Group 2 (animals R-3 and R-4) appear in the lower
graph.
Performance for R-1 ranged between 30% and 60% during the
initial four sessions.
During the following six sessions, however,
24
25
100-1
t::'
b.--!::..--&-b.··A--l::..
•'\
I
~\y\
.'6 ,{; /'0 CDI
I
I
80
I
I
'
:
60
0
40
~
20
0::
j
0
e
.
e
(l
I
R-2
I
I
I
I
306090120150
~<(
z 100
o
o--o
f--A-A
1\ i:..
2
~.,.i( \
/ r o·\
80-
I !
\ \ o
I
,I i
,, •
_P/
(/)
0
0
A----·1::..
z
u
&
e
o--G R-1
c
0
cr:
!::.. !::.. !::.. A
60
0
/ I
/
40
.\.I
.I
A
0
A/
o---o R-3
20
A.--A.
I
I
I
I
T-1-T
1 2 3 4 5 6 7 8 9 10
I
I
I
R-4 ·
I
I
306090120150
SESSIONS
Fig. 5
Mean diScrimination ratio (percentages)
for individual animals in the first ten
sessions and monthly retraining sessions
26
performance improved (60% to 90%).
The figure clearly shows the day-
to-day variation over the ten sessions.
In fact, accuracy of perfor-
mance did not stablize (80% or above) until 120 days after the start of
the experiment.
R-2, on the other hand, was performing at 90% accuracy
by Session 4 and remained at 100% accuracy throughout the remainder of
the experiment.
by Session 4.
In the lower graph, R-3 was performing at 85% accuracy
R~4
was performing at 90% accuracy by Session 4.
Each
animal, R-3 and R-4, missed one session because of illness., unrelated
to drug administration.
During the following six sessions, performance
improved. for R-3 but variability increased.
Performance for both R-3
and R-4 remained above 88% during the remainder of the
experiment~
Latencies for all acquisition sessions and retraining sessions are
presented in Fig. 6.
formed data.)
(All latency figures are plotted using untrans-
In general, latencies for all animals averaged less
than 3.00 sec per trial during acquisition.
There was substantial
variability in the performance of R-1, which did not stablize until
150 days from the start of the experiment.
Latency for R-2 remainded-
consistently between 0.30 and 0.76 sec on nondrug days throughout the
entire experiment.
The lower graph illustrates that both R-3 and R-4
generally decreased latency over the initial ten sessions (2.00 sec to
0.69 sec, and 1.00 sec to 0.64 sec, respectively).
Both R-3 and R-4
performed with latencies between 2.00 sec and 0.54 sec during the remainder of the experiment on nondruq days.
Probe trials (Session ll) were presented after the ten training
sessions.
I"~M~
Both animals in Group l erroneously responded to the IR
when presented with an lR paired with a RG (first probe) and an
1
27
3
2
0
0
-~
0
u
Q)
If)
>z
0
--,------r-1 I
j
w
I
I
I
I
I-
2 3 4 5 6 7 8 9 10
I
I
I
I
I
306090120150
1<(
_j
3
z
o-···O R-3
<(
w
~
A---A
2
R-4
0
A o
0
--r-1
I
I
I. r 1
I
I
I
I 2 3 4 5 6 7 8 9 10
SESSIONS
·--r~-.-11
306090120150
Fig. 6
Mean latency (s~conds) for individual
animals in the first ten sessions and
monthly retraining sessions
28
lR paired with a RB on the second probe.
For Group 2, both R-3 and
I
R-4 correctly responded to the RR M&M when presented with matched-pairs I
of red M&Ms.
DR and latency means for all animals did not change
during the four days in which probe trials were given.
In Sessinn 12 both R-1 and R-2 erroneously responded to the IR
M&M on the first probe but correctly responded to the RR M&M on the
second probe when presented with matched-pairs of red M&Ms.
R-3 and
R-4, also presented with matched-pairs, responded to the real M&M on
both probe trials.
For R-1 and R-2 in Session 13, probe testing was
identical in design and results to Session 12.
with two imaginary
M&r~1,
randomly selected the
R-3 and R-4, presented
t~1&f~s
in a delayed re-
sponse. ·In Session 14, Group 1 was presented with two probe trials
·consisting of two real M&Ms, one of which was red.
the RR M&M on both probe trials.
Both animals chose
R-3 anrl R-4, presented with the same
pr6be trials, randomly chose one of the real M&Ms.
In Session 15, all
animals were presented with four probe trials of matched pairs of red
M&Ms following saline treatment.
all four B_R
~1&f-1s,
R-1 and R-4 correctly responded to
hm,Jever R-2 and R:-3 responded correctly to only three
of the four RR M&Ms.
Although animals R-1 and R-2 were initially trained on color relevant and reality irrelevant, probe tests indicated that these animals
were able accurately to respond to the real M&M (by Session 15) when
color became irrelevant.
Therefore statistical analysis of the drug
data was performed using all animals as one group.
Mean percent correct responses for all animals for each drug
treatment on the DR measure was used in the calculation of a one-way
29
.
analysis of variance with repeated
.
mea~ures.
hand, were analyzed across the twelve
·dru~
Latencies, on the 6ther
treatments and over all
eighteen trials (probe trials were excluded) in a two-way analysis of
variance with repeated measures.
Reciprocal transformations were per-
formed on the latency data to reduce variance caused by the bimodal
distribution of scores.
DR and latency measures.
Table 1 presents a summary of the analyses for
A significant overall drug effect was observed
for both DR (F=5.91, df=ll/33, p<.Ol) and latency (F=3.37, df=ll/33,
p<.Ol).
Latency (time) within each drug treatment was found to be
nonsignificant (F=0.83, df=l7/51).
The interaction between drug treat-
ment and latency however was significant (F=l.30, df=l87/561, P<.001).
Figure 7 presents individual dose response curves for DR.
It is clear
from the figure that performance accuracy for all animals remained
relatively unchanged (DRs between 94% and 100%) following a LSD dose of
1 meg/kg.
However, all other doses produced consistent decrements in
accuracy (between a range of 89% and 22%) with the exception of R-4 at
doses of 8 meg/kg and 32 meg/kg.
DR for R-3 and R-4 were severely
impaired (DRs of 22%} at the highest dose of LSD.
Individual curves for latencies are presented in Fig. 8.
was no significant linear trend for the latency data.
There
All animals per-
formed at an average response time of less than 1.2 sec following treatment with 1 meg/kg.
R-1 and R-2 were impaired by 8 meg/kg (31.55 sec
and 21.55 sec, respectively) and at the two highest doses of LSD
(3.59 sec and 9.39 sec for R-1 and 3.22 sec and 6.77 sec for R-2).
R-3 ahd R-4; on the other hand, were severely impaired by only the
highest dose of LSD (51.78 sec for R-3 and 80.17 sec for R-4).
30
Table l
Analysis of Variance
Summary Table
Source
df
MS
F
33
0.017
5. 91 *
Drug Treatment
33
4.962
3.37 *
Latency
51
0.189
0.83
Drug x Latency
561
0.212
1.30 *
Discrimination Ratio
Drug Treatment
Latency
31
R-1
R-'2-
0
t:
0:::::
2..
Q
t:
z
!00'
·-~
R-3
\
;A...., R.- 4
\
I
\
.
"-...
I
\
\ I
\
'A
\
\
\
\
\
~
2
'0
16 32 64- \2~
I
S'
\G
3?...
64 \2.<6
LS b (meg/ ~g)
Fig. 7
Mean discrimination ratio for individual
animals as a function of LSD dose
32
50
R-1
I
I
30
I~
\0
5
u
(\)
I
I
I
I
I
I
{
I
\
I
3
\
I
I
I
R-2..
I
I
I
~.
([}
~I
I
I
It,
I
I
.4
)-
u
'Z.
UJ
\-<(
___,
50
R-3f
I
30I
53~
1-
J
/
I
to-
R-4
I
/\
I \
I
I
I
.
I
o-. - 0 - ·-a- . -<J-- . _o
I
\
\
I
\
I
\
\
.__AI
t
I
I
I
I
I
I
I
I
~--""
I
J6 32. 64 t2CO
\
'0
16
32 64 12<6
. LSD (me~/ k3)
Fig. 8
Mean latency for individ~al animals
as a function of LSD dose
33
Some ahimals were unable to respond on one or more trials after
treatment with certain doses of drugs, causing latency scores of 100
to be included in the analyses.
Table 2 presents the number of uncom-
pleted trials by each animal for each drug.
Most of the uncompleted
trials are associated with the administration of LSD, especially at the
highest dose.
Graphic representation for all drug treatments are presented in
Fig. 9 for DR.
The arrangement of doses is not in a chronological
iI
order as doses were given in a counterbalanced arrangement.
Mean accur-i
1
acy of performance remained relatively unchanged (above 95%) following
. treatment with saline, CAF, and LSD (l meg/kg).
doses of LSD decreased accuracy of performance.
However, increasing
LSD at a dose of
8 meg/kg decreased accuracy to 75% whereas a dose of 128 meg/kg decreased accuracy to 40%.
Both doses of CPZ also decreased accuracy.
A slight decrease was seen with the lowest dose of CPZ (89%) and
greater effects with the higher dose (79%).
Similarly, doses of DMT
also produced some decrement in performance accuracY.
DtH at a dose
of l mg/kg decreased performance levels to 89% and a dose of 2 mg/kg
decreased performance accuracy to 79%.
Mean latency scores and standard deviations for all drugs are
presented in Fig. 10.
Latencies averaged 0.67 sec for saline, 0.57 sec
for CAF, and 0.80 sec for LSD (l meg/kg).
LSD doses of 8 meg/kg and
32 meg/kg both increased latency to an average of 13.00 sec per trial,
However, LSD at a dose of 16 meg/kg produced a greater decrease in
latency (5.83 sec) when compared to latencies at a dose of 64 meg/kg
(2.38 sec).
Doses of CPZ produced divergent effects on latency.
At
a dose of 0.1 mg/kg, latencies remained unchanged from saline treatment.
34
Table 2
Number of Uncompleted Trials
LSD
CPZ
DMT CAF
------~----...... ~
1
8
R-1
3
R-2
2
16
64
128
.1
8
1
r-"-.
.5 . 1
2 10
1
1
R-3
R-4
32
5
9
3
14
1
100TIT
0 .~. " ~
o~- ....,ol.: .·r~fa~
'"~v· L
/~
v~/0,,"/~'i}/.~.
1
-·;/v7~
1
9
..
.•
T
80
0
.
: ..
.:···~·:::
/:::~..:-...... :
'
:.: .
':::::.i··.t·.i.'::·:
· ·..
/1 . -...
//V/:
/,//'(
I
... r/.. X;j/''//''/
·:: .. //- Y/...- ·v/-/
.::: . ' /"· Y/f/./1,:/{-" Y/t%1
.
:
Q:
60 . :: ..
s:;:
......
L1
.:.::.!
....
:."I.:
TI
'
::::-,.:-::-.1.: · {:::
t-.:..·:·
... ·.·:.. ·..
:::::...1·:-:+.::-:::..
........
~%~:0~7/~--»~0
' ·'
. :. ~~~~i~>·/~
J~;( .(// II·'": :"-: : ::.,,,,,.[i/i'
: : : :.:,-: · : : : : : : :
j-:·:::·:. . ·.: : :.: -: :_: :
:::-:-:-:. _ : . :....;.;..::
~
jtj~V//::(.~
~~'1-~
-~--/~--r~-/-/1 I ................. .
4 o ..::::
.. ~/"~~/~/..}~'l~v
/. );%'~r/.0 /h ~/-~7/?~/::-:}:/):-:~::\:}i\::
--//) ............ .
2:
30 -:::.
z
0
z
~
0:::
50 .. :
·.·:
20
. ..
::::.
I
~-~~~//f
/~ /-~~~.t/J.;::::·:·_::::.:.::.:::-:·:·:·:::::
//./) /Aj/, Y- :7.'0'/ }:;::::;-:;::.
(/~y1?~ 0 0 / / ' / ·....:-:-.-..:-:::·:._·..:-..
~/'
~1-/ ~W,,da:·::::::::::-:::: :.: : :-: : : : :.
_::::::::::::::y.
1
)~ ~ /~,rt iT
,,:.~
~-'':':,::'l:}:::;j
/~~/
, ••• ,
10 ,.••'
0
1·:-::::::::::::·:: ·::-::-;::;:::::;::
!"":
SALINE
/.z;jm
1
'
8
16 32 64
'
I
2
~
128~
LSD(rncg/kg)
10
EIN .....
CPZ
DMT CAFF I t:.
(mg/kg) (mg/kg) (mg/kg)
Fig. 9
Mean discrimination ratio for each drug
treatment averaged across all animals
w
01
36
90
80
70
(]
60
Q)
Ill
)-
u
z
w
50-
1<(
_J
40
T
z
<(
w
~
30
20
10
~----....SALINE
Fig. 10
Mean latency for each drug treatment
averaged across all animals
37
(0.66 sec) but at a dose of 0.5 mg/kg, latencies increased to 11.60
sec.
Doses of DMT produced similar effects.
A dose of 1 mg/kg slightly:
increased latencies t6 3.1 sec and a dose of 2 mg/kg increased latencies 1
to 8.08 sec.
Since several a priori hypotheses were made on certain drugs, subsequent comparisons involved using a Dunn's Multiple Comparison t test.
The comparisons
ihclud~d
the highest dose of each drug in order to
I
limit the number of comparisons.
Th~ five drugs used, LSD (128 mcg/kg),l
CPZ (0.5 mg/kg), DMT (2 mg/kg), CAF (10 mg/kg) and.saline, are presented
in Table 3.
The critical range (minimum value for significance at the
.01 level was equal to 13.65 for DR and 22.31 for latencies.
All dif-
ferences between means of two drug treatments exceeding these values
were significant.
Saline and CAF were nonsignificant on both DR anrl
latency measures (p<.Ol).
Individual comparisons between drug treatment
·means of saline or CAF and the other drugs, LSD, DMT, and CPZ were
significant only on the DR measure (p<.Ol).
All comparisons with LSD
however were found to. be significant on both behavioral measures
(p<.Ol).
DMT and CPZ were not signficantlydifferent on either the DR
or latehcy measure.
38
Table 3
The upper graph represents mean DR differences and
the lower graph represents mean latency differences.
The crit-
ical value for significance for the DR measure was equal to
13.65 and 22.31 for latency.
39
Table 3
Dunn's Multiple Comparison Test
LSD
LSD
DMT
CPZ
CAF
SAL
37*
.39*
55*
59*
·--
mn
2
CPZ
18*.
22*
16*
20*
4
CAF
SAL
SAL
SAL
CAF
CAF
DMT
CPZ
LSD
0.10
7.41
10.43 34.96*
7. 51
10.53 35.06*
orn
3.02 27. 55*
CPZ
24.53*
LSD
*P<. Ol
DISCUSSION
The results indicate that hallucinogenic drugs alter visual perceptions of objects as measured by accuracy of response and laten.cy of
response.
Other behaviorally active drugs, such as chlorpromazine and
caffeine, did not disrupt performance.
Accuracy of performance proved to be dose dependent for LSD.
While the lowest dose of LSD (1 meg/kg) was indistinguishable from
saline treatment, successively larger doses of LSD resulted in impairment of accuracy (Fig. 7).
Accuracy of performance decreased to
chance levels at the highest dose of LSD (128 meg/kg).
These results
I
are consistent with other LSD studies in which visual distriminations
were impaired (Siegel, 1969; Sharpe et al., 1967; Roberts and Bradley,
1967; and Brown and Bass, 1969).
Increasing doses of LSD also led to increased latency of response,
although not always in a linear manner (Fig. 8).
These results are
similar to those obtained by Fuster (1959) who reported an increase
in latency at the low dose range of LSD.
Brown and Bass (1969) also
observed a somewhat "sinusoidal" curve obtained on the latency measurement with comparable increasing doses of LSD.
To support the hypothesis that the effects obtained with LSD, the
prototypic hallucinogen, were also characteristic of other hallucinogens, DMT was used.
The peak effects (visual distortions, hallucina-
tions, etc.) of DHT are typically reported to be similar to those of
LSD, but with an earlier time of onset and a shorter duration.
drugs reduced accuracy of performance to about 75% and increased
40
Both
I
I
·I
41
latencies compared to saline treatment.
·LSD and
.
D~1T
As the data indicate, both
are simi 1ar with regard to the effect on DR and 1atency
(Figs. 9 and 10)'.
*
Further, to control for the possibility that the-observed behavioral drug effects might be due to CNS stimulation or
d~pression,
rather than hallucinogenic properties per se, a CNS stimulant (CAF)
and depressant (CPZ) were used.
Administration of CAF produced a slighi
decrease in latency time, an effect which has been reported by many
investigators (Blough, 1957; Pare, 1961) studying the effects of
chemical stimulants on motor responses, but was indistinguishable from
saline baseline tests on accuracy of response (Figs. 9 and 10).
Conversely, the depressant effects of CPZ were manifest in increased latency times and decreased accuracy of performance (Figs. 9
and 10).
The effects of CPZ as measured by DR and latency indicate a
similarity in performance impairment between this phenothiazine at a
dose of 0.5 mg/kg and the dose of 2 mg/kg of the hallucinogen, DMT.
The occurrence of similar error tendencies (DR and latency) with CPZ
and DMT, however, reflect dissimilar central processes.
For example,
in the case of CPZ, results from a behavioral and EEG study (Bakay
Pragay and Mirsky, 1972) have characterized the nature of the CPZ
deficit as a consistent defect in arousal coupled with a slowing down
but not blocking of the sensory information received.
In the case of
DMT however, the deficits in performance appear more as a distortioh
*
Data obtained after this paper was completed indicate that performance under Dr•1T in a range of doses up to 4 mg/kg was similar to the
effects found with LSO but not similar to the effects found with comparable doses of CPZ.
42
in sensory perceptual processing.
This is consistent with the data
obtained in the present study with LSD, in that there appears to be a
disruption in the ability to perceive the precise stimuli which differentiate real from nonreal objects.
This disruption in perceptual abilities following treatment with
hallucinogens can, in another sense, be considered a visual distortion,
as in a case of an hallucination.
It maj be speculated that the real
and nonreal stimuli are taking on other characteristics for the experimental animal, leading to alterations in the dimensions of brightness,
size and shape (dimensions which normally aid discrimination), and,
therefore, tausing the stimuli to appear less distinguishable.
In-
creased responding to the i 11 usory stimulus demonstrates that this
previously accurate discrimination performance has been altered in some
way by LSD.
These inaccuracies could also be considered changes in
perceptions of reality, often reported by humans.
Other evidence supporting the idea that perceptual distortions and
ambiguous reality cues are the cause of performance impairment is
presented by Lowe (1972).
In an experiment testing LSD on the arousal
level of stimuli to which animals were exposed, as measured by responsecontingent light, it was observed that LSD increased arousal levels to
the extent that the animal became less likely to respond to produce a
stimulus change.
This increased sensory changie under LSD in combina-
tion with the illusory stimuli would possibly explain the animals'
inability to accurately discriminate between real and nonreal objects.
This LSD effect is consistent with reported drug effects on
learning and memory, in that certain drugs partially block sensory
43
input often. causing impairment of
(Jarvik~ 1969).
barbital~
However~
many CNS
drugs~
retention or retrieval
such as
etc., impair learning but do not cause
in the present
study~
pento-
hallucinations~
and~
The hallucinogens LSD and DMT did decrease
but as previously pointed
breakdown in stimulus
CPZ~ CAF~
did not significantly or consistently impair
discrimination performance.
accuracy~
registration~
control~
out~
.·
not because of a general
but probably as a result of specific
hallucinogenic effects resulting in inaccurate perceptions of reality
cues.
This interpretation suggests that animals are likely to ex-
perience perceptual hallucinations and
illusions~
similar to those
reported by humans.
An important aspect of this discrimination involved an experimental design which used a different type of illusion, namely a mirror
image illusion.
This particular type of illusion is unique, in that
it 1) measures perceptions of reality
real and illusory
stimuli)~
(e.g.~
discriminating between
and 2) enables the subject to directly
verify whether the stimuli are real or not.
illusion experiments,
e.g.~
illusions, or angular
distortions~
Other geometric or spatial
the MGller-Lyer illusions, rectangular
have all clearly demonstrated that
animal perceptions are very similar to human perceptions, in that both
respond in a systematically inaccurate fashion.
objectively hallucinogenic drug effects in
Hov1ever, to assess
animals~
it is important
that a motor response be part of the task so that the animal is able
to physically validate perceptions of the stimuli that are discriminated as real.
By using a mirror image of one of the stimuli, this
becomes possible.
As a
result~
the animals were required to make a
!
44
11
reality judgement 11 on each trial, being immediately reinforced with
the M&M which could be eaten.
The mirror image was.unique in that it rliffered from the real
object in many of the same dimensions which humans report to be
affected by hallucinogens, i.e., size, shape, color, etc.
Therefore
when LSD is administered, it can be expected that the ambiguity betweeh the real and illusory stimuli will become even more pronounced,
causing errors to increase.
Another important aspect of the experiment involved the degree to·
which relevant and irrelevant cues were used on each trial.
formance of
ani~als
The per-
in Group l, following the initial probe tests,
appear to substantiate the hypothesis of noncontiguity theorists,
Sutherland and Mackintosh (1971), in that the response strength of
th~
reality ~ue was eventually strengthened by reinforcement while the
response strength of the color cue was weakened.
to the red, illusory
t~1M1
Repeated responses
demonstrated that the animals had little or
no information about the reality cues.
However, after repeated presen-
tation (perhaps overlearning) of the reality cues in both training and
probe .trials., reality became the controlling dimension.
The opposing
view of contiguity theorists would have argued that both color and
reality cues would initially be learned and that error responding would
be minimal following the reversing of reinforcement contigencies.
The observed data are also compatible with the work of Sutherland
and Holgate (1966) and Warren and Warren (1969).
Both groups suggest·
. that the more subjects learn about one cue the less is learned about
another.
Sutherland and Warren both make it clear, however, that
45
potential learning is occurring not only on the reinforced cue but on
the nonreinforced cue as well.
In fact, several studies have shown
that if more than one relevant cue is used in a discriminat.ion problem,
accuracy (Eninger, 1952) and the rate of acquisit1on (Warren, 1952) will
The presentation of two relevant cues, color and reality, for
improve.
Group 1 opposed to a single salient cue, reality, for Group 2, could
have facilitated performance dn the highest dose of LSD.
Animals in
Group 1 performed with 50% greater accuracy than animals in Group 2,
who had only one relevant cue.
The animals in Group 2, however, made
fewer responses than the animals in Group 1 (Table 3).
Whether this
was due to loss of stimulus control by the relevant cue, or idiosyncratic drug effects producing total response impairment, is uncertain,
··but the question poses a intriguing field of investigation for further
research.
Thes~
data support the notion that irrelevant cues are not only
learned during training, but can also act as discriminative stimuli,
particularly in cases where the relevant cue has been disrupted or is
not present.
The present experimentation therefore clearly indicates
that the effect~ of LSD do indeed disrup~ motor responses and visual
perceptions on a discrimination task between real and illusory objects.
This disruption was not significantly observed with other behaviorally
active drugs, i.e., CPZ and CAF.
Furthermore, the disruptive effects
of LSD as measured by DR and latency indicate that performance is dosedependent, although not always in a linear manner.
It
now remains to investigate whether other hallucinogenic drugs,
at comparable doses, achieve comparable effects.
The present operant
46
task allo\'IS the evaluation of several types of drugs.
Further investi-
gations varying relevant cues as well as drug treatments will contribute
to a understanding of perceptual processes involved in real-illusory
.
i
discriminations as well as lead to the development of a model of psycho-!
tomimetic effects.
References
Aggernaes, A. The difference between the experienced reality of
hallucinations in young drug abusers and schizophrenic patienti.
Acta Psychiatrica Scandinavica, 1972, 48, 287-299.
Bakay Pragay, E., ~~i rsky, A. F. The nature of performance deficits
under secobarbital and chlorpromazine in the monkey: a behavioral
and EEG study. Psychopharmacologia, 1973, 28, 73-85.
Baldwin, M., Lewis, S. A., Bach, S. A. The effects of lysergic acid
after cerebral ablation. Neurology, 1959, ~. 469-474.
Becker, D. I., Appel, J. B., Freedman, D. X. Some effects of lysergic
acid diethylamide on visual discrimination in pigeons. Psychopharmacologia, 1967, Jl, 354-364.
Blough, D. S. Some effects of drugs on visual discrimination in the
pigeon. Annals of New York Academy of Scienc'e, 1957, .§_§__, 733-739.
Brown H., Bass, W. C. Effects of drugs on visually controlled
avoidance behavior in rhesus monkeys: a psychophysical analysis.
Psychophannacologia, 1967, Jl, 143-153.
Davis, R. T.
~·1onkeys
as perceivers.
New York:
Dixon, J. W. (Ed.) _Biomedical computer programs.
University of California Press, 1975.
Academic Press, 1974.
Los Jl.ngeles:
Dominguez, K. W. A study of visual illusion in the monkey.
of Genetic Psychology, 1954, 85, 105-127.
Journal
Dykstra, L. A., Appel, J. B. Effects of LSD on auditory perception:
a signal detection analysis. ~chopharmacologia, 1974, 34, 289-307.
Eniger, M. W. Habit selection in a selective learning problem.
Journal of Comparative Physiolo~y and Psychology, 1952, 45, 604-608.
Ferraro, D. P. Effects ofA9-trans-tetrahydrocannabinol on simple and
complex learned behavior in animals. In M. F. Lewis (Ed.), Current
Research in t1arihuana. New York: Academic Press, 1972.
Fischer, R. A cartography of the ecstatic and mediative states.
Science, 1971, 174, 897-904.
Fischer, R. A pharmacological and conceptual reevaluation of
hallucinations. The Pharmacologist, 1974, 1..§:, 237.
Flagg, S. F., Medin, D. L. Constant irrelevant cues and stimulus
generalization in monkeys. Journal of Comparative Psychology and
fbl__siology, 1973, 85, 339-345.
47
48
Fuster, J. M. Tachistoscopic perception in monkeys.
Proceedings, 1957, JQ, 43.
Federation
Gellerman, L. W. Change order of alternating stimuli in visual
discrimination experiments. Journal of Genetic Psychology, 1933,
!!1_, 206.
Goodman, L. A., Gilman, A. (Ed.) The pharmacological basis of
therapeutics. London: The Macmillan Co., 1970.
Harris, A. V. Perception of the horizontal-vertical illusion by
sturnptail monkeys. Radford Review, 1968, g, 61-72.
Hoffer, A., Osmond, H.
1967.
Hull, C. L.
1943.
The hallucinogens.
Principles of behavior.
New York:
New York:
Academic Press,
Appleton-Century,
Jarvik, M. E., Abramson, H. A., Hirsch, M. W. Lysergic acid
diethylamide (LSD-25): IV. effect on attention and concentration.
Journal of Psychology, 1955, ~. 373-383.
Jarvik, M. E., Chorover, S. Impairment by lysergic acid diethylamide
of accuracy in performance of a delayed alternation test in monkeys.
Psychopharmacologia, 1960, l• 221-230.
Jarvi k, fv]. E. Effects of drugs on memory. In P. 131 ack (Ed.), Drugs
and the Brain. Baltimore: Johns Hopkins Press, 1969.
Keppel, G. Design and analysis: a researcher•s handbook.
New Jersey: Prentice Hall, 1973.
E~glewood,
Kornetsky, C., Humphries, I., Evarts, E. V. Comparison of psychological effects of certain centrally acting drugs in man. Archives
of Neurology and Psychiatry, 1957, ll_, 318-324.
Krechensky, I.
516-532.
Hypotheses in rats.
Psychological Review, 1932,
~.
Lagutina, N. I., Laricheva, IC. A., Mil 1 Shtein, G. I., Norkina, L. N.
Effect of D-lysergic acid diethylamide on higher nervous activity
in baboons. Federation Proceedings, 1964, ~' 737.
Lashley, K. S. Brain mechanisms and intelligence: a quantitative
study of injuries to the brain. Chicago: University of Chicago
Pres s , 1929 .
Lowe, G. The effect of LSD-25 on light-reinforced behaviour in the
rat. Psychopharmacologia, 1972, ~, 255-264.
,49
Lyon, J., Thomas, D. R. The influence of postural distortion on the
perception of visual vertical in pigeons. Journal of Experimental
Psychology, 1968, ~. 120-124.
Malott, R. W., Malott, M. K., Pokrzywinski, J. The effects of outward-1
pointing arrowheads on the Muller-Lyer illusion in pigeons.
I
Psychonomic Science, 1967, ~. 55-56.
Mumma, R., Warren, J. M. Two-cue discrimination learning by the cat.
Journal of Comparative Psychology and Physiology, 1968, 66, 116-122.
Pare, W. The effect of caffeine and seconal on a visual discrimination
task. Journal of Comparative Psychology and Physiology, 1961, 54,
506-509.
Reid, J. B., Medin, D. L., Davis, R. T. Perception of verticality by
monkeys. Journal of Comparative Psychology and'Physiology, 1965,
60, 208-212.
Revesy, G. Experiments on animal space perception.
of Psychology, .1924, J.i, 386-414.
British Journal
·Riley, D. A. Discrimination learning: contemporary topics in
experimental psychology. New York: Allyn and Bacon, 1968.
Roberts, M. H. T., Bradley, P. B. Studies on the effects of drugs on
performance of a delayed discrimination. Physiology and Behavior,
1967, ~. 389-397.
Savage, C. W. The continuity of perceptual and cognitive experiences.
In R. K. Siegel and L. J. West (Ed.), Hallucinations: behavior,
experience, and theory. New York: John Wiley &Sons, 1975.
Sharpe, L. G., Otis, L. S., Schusterman, R. J. Disruption of size
discrimination in squirrel monkeys (saimiri sciureus) by LSD-25.
Psychonomic Science, 1967, I(3), 211-223.
Siegel, R. K. ·Effects of cannabis sativa and lysergic acid
diethylamide on a visual discrimination task in pigeons.
pharmacologia, 1969, ji, 1-8.
Psycho~
Siegel, R. K., Lebowitz, M., Jarvik, M. E. Ketamine-induced visual
imagery in surgical and non-surgical patients. Unpublished study,
1971.
Siegel, R. K., Brewster, J. M., Jarvik, r~. E. An observational study
of hallucinogen-induced behavior in unrestrained ~acaca mulatta.
Psychopharmacologia, 1974, 40, 211-223.
·Siegel, R. K., West, L. J. (Ed.) Hallucinations: behavior, experience,
and theory. New York: John Wiley & Sons, 1975.
1
50
K. W. The nature of discrimination learning in animals.
Psychology Review~ 1936~ 43~ 427-449.
Spence~
N. S.~ Holgate, V. Two-cue discrimination learning in
rats. Journal of Comparative Psychology and Physiology~ 1966~ _§]_~
198-207.
Sutherland~
N. S.~ Mackintosh~ N. J. Mechanisms of animal discrimination learning. New York: Academic Press~ 1971.
Sutherland~
C. J.~ Baar, J. The Muller-Lyer illusion in the ring dove,
turtur risorius. Journal of Comparative Psychology, 1929~ ~~
275-292.
Warden~
Warren, J. M. Some stimulus variables affecting the discrimination of
objects by monkeys. Journal of Genetic Psychology, 1956~ 88~ 77-80.
J. M.~ Warren, H. B. Two-cue discrimination learning by
rhesus monkeys. Journal of Comparative Psychology and Physiology,
1969~ ~. 688-691.
Warren~
J. f·1., ~1cGonigle~ B. Attention theory and discrimination
learning. In R. M. Gilbert and N. S. Sutherland (Ed.), Animal
discrimination learning. New York: Academic Press, 1971.
\1arren~
Webster 1 s Third New International Dictionary.
G & C Merriam Co., 1971.
Springfield~
Mass.:
D. I. Constant irrelevant cue learning in the pigeon.
Animal Behavior, 1967, 15, 229-230.
Williams~
C. N. Visual illusions in the chick.
1933, No. 153~ 4-83.
t~inslow,
Archives of Psycho.J.Qgy_,