Abstract
In mirror mark tests dolphins twist, posture, and engage in open-mouth and
head movements, often repetitive. Because postures and an open mouth are
also dolphin social behaviors, we used self-view television as a manipulatable
mirror to distinguish between self-examination and social behavior. Two
dolphins were exposed to alternating real-time self-view ("mirror mode")
and playback of same, to determine if they distinguished between them. The
adult male engaged in elaborate open-mouth behaviors in mirror mode, but
usually just watched when played back the same material. Mirror mode behavior
was also compared to interacting with real dolphins (controls). Mark tests
were conducted, as well as switches from front to side self-views to see
if the dolphins turned. They presented marked areas to the self-view television,
and turned. The results suggest self-examination over social behavior.
An animal demonstrates self-recognition if it treats its mirror image
as a reflection of itself, and not as another member of its species (Gallup,
1970). Apes and monkeys exposed to mirrors and real-time television have
been tested for self-recognition by examining their response, when fully
awake, to a conspicuous mark placed on their forehead while they were under
anesthesia. Chimpanzees, orangutans, and gorillas exhibit self-recognition
by attempting to remove the mark (Gallup, 1970; Lethmate and Ducker, 1973;
Suarez and Gallup, 1981; Parker, 1989; Patterson, 1984, 1991, 1994), whereas
monkeys and lesser apes (gibbons) interact socially with their marked mirror
image (Gallup, 1979, 1982; Patterson, personal communication). Data from
a previous study suggest that dolphins, like the great apes, may also use
a mirror for self-examination (Marten and Psarakos, 1994).
In a 2 1/2 year study of bottlenose dolphin interaction with mirrors we
found very suggestive evidence for self-recognition in this species (Marten
and Psarakos, 1994). The study consisted of mirror mark tests and controls
with five individuals. In the mark tests the dolphins appeared to use a
4 ft. diameter mirror to examine a zinc oxide mark on their side by using
various maneuvering and twisting postures. (Unlike dyes for primates, zinc
oxide is a tactile stimulus as well as a visual one.)In the control tests,
mirror behavior and interaction with a real stranger through an underwater
barred gate were quite different, the most outstanding difference being
that the dolphins attended to a real stranger for close to 100% of a several
hour test period, whereas they attended to a mirror for less than 1% of
the time.
The lack of a hand to touch the mark (or mirror) makes the mark test less
definitive for dolphins than it is for primates. Additionally, many of the
behaviors that dolphins use in front of a mirror resemble social behaviors
as described by Pryor (1975), Overstrom (1983), Ostman (1985; 1991), and
Norris (1991). In the mirror/no mark situation the dolphins often engaged
in rhythmic and repetitive head, mouth, and body movements. Open-mouth behavior,
head movements, and posturing may also occur when a dolphin is threatening
another dolphin, or merely excited. So, if a dolphin exhibits unusual or
extreme posturing in the mirror while looking at his mark, or makes head
or mouth movements, it is possible that the dolphin is using the postures
or behaviors to interact "socially" with what he perceives to
be another dolphin in the mirror. However, a self-aware species might use
some of its social repertoire while examining its mirror image.
Our research used various forms of manipulated video as a tool to differentiate
between self-examination and social behavior, as well as to devise alternative,
species-appropriate methods of testing for self-awareness (Gallup, 1979).
In the first test, we hypothesize that if dolphins recognize themselves
on television, their behavior should be different with a real-time self-view
("mirror mode") than it is when they are shown taped playback
of the same mirror mode material. The test is designed to elicit one response
if the dolphin mistakes its television image for another dolphin, and a
different response if the dolphin differentiates between real-time self-view
and playback. In the second series of tests we present control data on dolphin
interactions with real strangers, for comparison with mirror mode behavior.
The third series of tests compares marked dolphin behavior in mirror mode
with playback mode. In the fourth series, the turn tests, we examine whether
dolphins turn when the real-time display on their television is suddenly
switched from the usual frontal view to a side view. (Gallup, 1979 and 1987,
suggests an alternate turn test setup using a phony background probe.) None
of the research was done with food rewards, so all results were voluntary
actions on the part of the dolphins.
Methods
Video setup. We used a Minolta S-VHS Series V-2000 video camera with
a Sigma 0.6 wide angle lens. The camera was located to the dolphins' left
of the television (Fig. 1). We also used one Panasonic AG-1960 S-VHS VCR
for playback to the dolphins, and another AG-1960 for recording the camera
data. The television was a 20" Sony Trinitron Color television.
Figure 1. Two-tank complex (top view) and underwater viewing laboratory,
Sea Life Park, Hawaii. The camera next to the 20" television in the
small square window provided the frontal self-view on the television (mirror
mode) for the television tests. Cameras in the concave windows provided
the side views of the dolphins which were shown to them in the turn tests.
Figure 2. (A) Mirror mode. When we display his real-time self-view
image on the television ("mirror mode"), adult male Keola engages
in repetitive head and open-mouth movements. (B) Playback mode. When these
same open-mouth movements are played back to Keola (inset) he just watches
and does not make open-mouth movements in response. (The inset is all he
sees; it fills the whole screen.)
Figure 3. (A) Open-mouth movements in response to a real dolphin
are frenzied biting. (B) Keola has maneuvered so that the mark on his right
side shows on the monitor even though the camera is to his left. (C) Wide
open mouth following the application of denture adhesive to the teeth. (D,
E, and F) Frontal view (D) is changed to side view (E), then dolphin turns
(F). (G and H) The tongue curl (G) and presentation of a fish after eating
it (H) are examples of unique behavior in front of the self-view television.
Figure 4. Television Test: Behavior in "mirror mode"
vs. "playback mode". The bar graphs represent the total counts
over all sessions in each mode divided by the total time in that mode. See
text for a description of these behaviors. (A) Keola, adult male (14 years).
(B) Hot Rod, juvenile male (6 years).
Methods
First-time encounter through an underwater barred gate: one adult male and
four adult female dolphins. The control experiment which most closely
resembles our test situations was presented in Marten and Psarakos (in press).
Four adult female dolphins were in the large tank (Fig. 1) and an adult
male, Kamalii, they had never met was put in the adjacent small tank. They
were separated by an underwater gate with bars 15 cm apart (Fig. 3A).
First-time encounter with no gate: two adult males (Keola and Maka).
Keola was moved from our research tank and put directly into a tank that
contained an adult male, Maka (15-20 years), whom Keola had never met. In
this new tank he could also see and hear two dolphins he had not seen for
several years (an old adult male and an adult female) through a metal, underwater
barred gate. We observed and videotaped the dolphins' behavior from the
surface for the first two hours after Keola's arrival.
First-time encounter through an underwater barred gate: three adult male
dolphins, one juvenile male dolphin, and two juvenile false killer whales.
Two false killer whales, a male and a female, were introduced across an
underwater barred gate to four bottlenose dolphins, three adult males and
juvenile Hot Rod. Although the dolphins had previously lived with a false
killer whale, they had never met these two. The male false killer whale
was introduced alone, then approximately 15 minutes later the female joined
him. We observed and videotaped the encounter from the surface for one hour.
(False killer whales are very closely related to bottlenose dolphins. They
have mated and had fertile offspring at our facility.)
Control Tests Results
First-time encounter through an underwater barred gate: one adult male dolphin,
four adult female dolphins. The dolphins attended to each other for
the majority of the 40-minute test period. A narrow channel between the
two tanks may have restricted the dolphins. Open mouth behavior occurred
on both sides of the gate, and was intense and frenzied, much like rapid
biting (Fig. 3A).
First-time encounter with no gate: two adult males (Keola and Maka).
As soon as Keola was put in the tank, he and Maka swam together rapidly
around the tank. They stayed close, even jumping out of the water together,
for approximately the first five minutes. They spent much of the next two
hours continuing to swim close together, slower than at first, and without
jumps. Throughout this swimming and in most of the gate behavior described
below, Keola repeatedly put his rostrum near Maka's genital area.
Maka engaged in most of the gate encounters with the two neighboring dolphins,
with Keola positioned behind him in the rostral-genital position. Keola's
first major interaction at the gate occurred fifteen minutes after arriving
in the new tank. The interaction was violent, with fast movements and quick-moving
open-mouth behavior; head movements were hard to see, but if present were
not pronounced. This encounter lasted approximately 10-20 seconds. Keola's
subsequent encounters were less violent, shorter, and did not appear to
have open-mouth behavior. His orientation to the gate was always perpendicular.
Keola interacted at the gate approximately 10-15 times in the two hours.
First-time encounter through an underwater barred gate: three adult male
dolphins, one juvenile male dolphin, and two juvenile false killer whales.
When the male false killer whale was put in the tank, all four dolphins
immediately swam to the gate. The dolphins remained oriented perpendicular
to the gate throughout the one-hour observation period, with only a few
brief departures after 25 minutes. The male false killer whale spent several
minutes at the gate, facing the dolphins. There was a period of prolonged,
rapid, and loud airborne vocalizing during the confrontation across the
gate. After the female false killer whale was introduced the two whales
swam close together breathing in synchrony, and circled their tank for the
remainder of the observation period. There were no more direct encounters
between the whales and dolphins at the gate. The dolphins' orientation was
always perpendicular to the gate, never parallel. There appeared to be little
or no posturing. The dolphins blew bubbles at least four times, once as
a bubble stream. One dolphin spun once on its long axis. There was occasional
open-mouth behavior, but apparently without simultaneous head movement.
Control Tests Discussion
First-time encounter through an underwater barred gate: one adult male dolphin,
four adult female dolphins. In this test, the adult male Kamalii exhibited
all the social behaviors found in real social encounters but absent in mirror-directed
behavior: long individual attention; frenzied, intense movements, including
rapid biting movements; perpendicular rather than parallel orientation to
the gate; intense, loud vocalizations; and lack of cyclic movements of the
body and head. The females exhibited similar behavior, somewhat mitigated
by the narrow channel on their side of the gate.
First-time encounter with no gate: two adult males (Keola and Maka).
It is clear from this example of a strange encounter that if two stranger
dolphins are introduced and have physical access to each other, the ensuing
interaction is fast-paced, physically close, and contains strong movements.
Overall, Keola's behavior with Maka, and with old friends through the gate,
bore little resemblance to his mirror mode behavior: he moved fast and frenzied
with the real dolphins, whereas he acted calmer in front of the television.
(Keola's gate behavior was most likely affected by the excitement of being
in the tank with Maka.) It is not clear whether the difference in his behavior
is attributable to situational differences (a "mirror dolphin's"
behavior is limited: he can't swim around the subject or jump out of the
water), or to Keola's awareness of the true difference between his mirror
image and a real dolphin.
First-time encounter through an underwater barred gate: three adult male
dolphins, one juvenile male dolphin, and two juvenile false killer whales.
There were both similarities and differences between the dolphins' stranger
encounter with false killer whales and the television-directed behavior
we have witnessed in our research. Bubble blowing, open-mouth behavior,
and body spins occurred in both the stranger encounter and both television
modes. During the stranger encounter, all four dolphins were fixated at
the gate, and other than for a second or two did not leave it. In mirror
mode television, dolphins' visits are brief, and attention span is on the
order of seconds or minutes rather than hours. Thus, if we postulate that
the dolphin perceives its mirror mode image to be a stranger, the amount
of attention it gives the stranger on the television bears little resemblance
to the amount of attention it pays to a real stranger. And finally, although
open-mouth behavior occurred in both the stranger encounter and in mirror
mode, open-mouth behavior in mirror mode is often accompanied by head movements,
either side-to-side, up-and-down, or in circles; these were not noticeable
in the stranger encounter.
Methods
The concept of a mirror mark test was combined with the television tests
described above. If the marked dolphin is interested in the mark and aware
of his relation to the image on the television, he should use mirror mode
to observe the mark, not playback mode. Keola and Hot Rod had three mark
tests of this type; we present data on one of Keola's tests, since his positive
mirror mark test made him an interesting subject for comparing television
results with mirror results. The time samples in this test are too small
for statistical tests, so the results must be treated as tentative suggestions
rather than conclusions.
In addition to his mirror mode image on television, a .8 m by .7 m size
rectangular mirror was also available 3/4 m to his left. The mirror was
a reflective, aluminum-coated polyester mylar film made by DuPont, which
we applied to the window with soap and water. Keola was marked on the head
with zinc oxide, 2-3 inches behind his right eye (Fig. 3B). The video setup
was identical to that in the Mirror Mode/Playback Tests described above.
The self-view camera was beside the television on the dolphins' left (Fig.
1).
For analysis, the questions we tried to answer were: "Does the dolphin
increase the television viewing time of his marked area once he is marked?
Does he favor it more in mirror mode compared to playback mode?". We
tallied the amount of time Keola had his left and right sides facing the
self-view camera, and thus visible to him on the television, during three
10 minute segments: 10 minutes of control data without a mark, and 10 minutes
each of mirror and playback modes with a mark on his right side. For analysis
of the unmarked (control) segment we chose a 10 minute sample with a high
incidence of television interaction to give us a lot of data.
In all the television experiments presented here the location of the camera
to the dolphins' left means that if the dolphins do not favor showing a
side, the left side will automatically show more on the television - and
this is reflected in the data below. The dolphins were marked on their right
side specifically to see if they would counter this bias by maneuvering
the marked side into view.
Television Mark Test Results
In the control data, Keola spent eight of the 10 minutes directly in front
of the television looking at himself. During the first mirror/playback cycle
after his mark was applied Keola was directly in front of the television
2.43 minutes out of 10 minutes in mirror mode, and 2.30 minutes out of 10
minutes in playback mode. In the 10 minutes of unmarked control data, the
left (unmarked) side was "favored" 45% of the time and the right
(marked) side 10% - the bias expected with the camera on the dolphins' left.
In playback mode the left side was favored 68% of the time, the right side
8% - again as expected with the location of the camera. In mirror mode,
however, although the left side was favored 51%, the right side increased
to 25%. Exposure of the marked side in mirror mode (Fig. 3B) was thus three
times what it was in playback mode and 2 1/2 times what it was in the unmarked
control.
Television Mark Test Discussion
The mark on Keola's right side increased Keola's viewing time of that side.
It did not affect how long Keola spent at the monitor in mirror mode compared
to playback mode, but only his orientation when he was there (Fig. 3B),
tripling viewing of the right side. In a television mark test not presented
here, adult male Kamalii (marked with zinc oxide on his side) repeatedly
pivoted his body back and forth while watching his image on the television.
He appeared to be comparing his marked and unmarked sides. He did five cycles
(10 full lateral presentations) in 20 seconds. He never did this unmarked.
The tests with Keola involve small time samples, and though the results
are consistent with self-examination, they fall far short of proving it.
Future research will require larger samples and even new methods to be conclusive.
Methods
Video equipment. We used two Minolta S-VHS Series V-2000 video camera
with wide angle lenses. The front view camera was located to the dolphins'
left of the television. The side view camera was located in the bubble window
to the dolphins' right. The television was a 20" Sony Trinitron Color
television, set back roughly 8 cm from the window.
Sample. Babies Maui and Tinkerbell were given a frontal, real-time
self-view on television (Fig. 3D), but while they were watching it we switched
what was on the television to a real-time side view of themselves (Fig.
3E). We then waited for approximately five to ten seconds to see if the
dolphin turned (Fig. 3F). Maui and Tinkerbell were either alone or with
Maui's mother Puna during these experiments. Session 1 of these turning
trials occurred in June 1991, session 2: three months later, session 3:
two weeks later yet, and session 4: a month later.
Control data: counting turns in mirror mode without switching views.
The baseline data to which we compared turn test results was collected by
counting turns made by the subjects watching television in mirror mode,
when no switching of view occurred. Control data was collected only when
the dolphin was in front of the television looking at itself (as in Fig.
3D). For Maui and Tinkerbell, we examined a total of 100 minutes of mirror
mode videotape, chosen from three days of mirror mode experiments. The first
set was from five days before their first turn test, the second from two
days before their second turn test, and the third from the day of their
second turn test (prior to it).
Turn Test Results
In the control data Maui turned to the right once in a cumulative total
of 2.08 minutes of close viewing (when he was in front of the television,
looking at himself); Tinkerbell never turned in 1.6 minutes.
In test session 1, no turns occurred in eight trials. In session 2, Maui
turned in two trials out of eight. The first time he turned away from the
side-view camera, then toward it. The second time he turned twice toward
the camera, then away from it. In session 3, Maui turned once and Tinkerbell
twice in 13 trials, all toward the side-view camera. In session 4, Maui
turned in six trials and Tinkerbell in three trials, out of 26. In the first
turn of this session, Tinkerbell turned away from the camera. All subsequent
turns by both dolphins were towards the camera. In one of his turns, Maui
turned toward the camera twice.
Turn Test Discussion
The control data suggest that turns occur at a rate of approximately once
per two minutes of close viewing in Maui, and infrequently if at all in
Tinkerbell. If a trial lasts an average of approximately 5 seconds, we might
thus expect Maui to turn "randomly" once per 24 trials, and Tinkerbell
not at all. (These estimates are rough, as the actual amount of time we
allowed for a turn to occur varied slightly from trial to trial.) Instead,
after the first session when they did not seem to react to the switching,
Maui turned nine times in 47 trials and Tinkerbell, in sessions three and
four, turned five times in 39 trials. For Maui the turn rate in the tests
was about five times what it was in the control data. Tinkerbell never turned
in the control data, making her six turns during testing all the more significant.
Interpretation of Combined Results From Mirror Mark and Television
Tests
The most important conclusions we can make come from combining the results
of the mirror mark tests (Marten and Psarakos, 1994) with the television
tests presented here. The television mark test and turn test, although interesting,
can only be taken to be suggestive.
Keola, the only adult to have both mirror mark tests and television tests,
behaved significantly differently in mirror mode as compared to playback
mode (Figs. 2 and 4). His behavior strongly suggests that he did not perceive
the television image as another dolphin in either mode and was not interacting
with it "socially". When he was marked with zinc oxide, he almost
immediately positioned himself within a foot of the mirror so that the mark
could have been visible to him and engaged in rapid, extreme, postures for
13 seconds. It is very likely that he was examining his mark. The only reasonable
alternative, that he might have been posturing socially to what he believed
to be another dolphin in the mirror, is rendered not very likely by the
television tests.
The juvenile Hot Rod had both mirror mark and television tests. His behavior
during his mirror mark tests is hard to interpret. During his first mark
test he remained relatively motionless with his marked side facing the mirror
for 10 seconds. This lack of motion in front of the mirror is unusual for
Hot Rod, whose name derives from his kinetic energy. In his television tests,
we could not tell if he treated mirror mode differently than playback mode
- he acted interested and excited in both television modes with behaviors
like bubble blowing, head and mouth movements, and body spins. He did not,
however, act agitated like we would expect him to in the presence of a strange
dolphin, or give prolonged, undivided attention as he did during the control
test with the false killer whales. Some behavioral differences between mirror
mode and playback mode are, however, worth noting for Hot Rod (Fig. 4).
He did "Body spins with closed mouth" in mirror mode, but never
in playback mode. "Bubbles heard" were greater in mirror mode
than in playback mode for Hot Rod, suggesting increased excitement and interest
in mirror mode. These interested, but hard to interpret behaviors are similar
to the results obtained by Marino et al. (in press) in similar tests with
two juvenile males of approximately the same age (7 years old).
Self-View Television Behavior Compared To Encounters With Real Strangers.
The most marked differences between self-view television behavior and known
social behavior are attention and intensity. Open-mouth and head movements
are slow, relaxed, and rhythmic in front of the television, but rapid and
agitated when interacting with a live, unknown dolphin. Some of the television-directed
open-mouth behaviors exhibited during mirror mode are unique and do not
occur in other contexts, such as Hot Rod's presentation of his fish and
Kamalii's tongue curling (Fig. 3G and below). In general, the dolphin attends
to a real stranger close to 100% of the test time, but less than 1% of the
time when viewing itself on real-time self-view television. Behavior in
front of the self-view television is usually calm and involves exploring
the television image. Head movements and open-mouth behavior appear to be
"contingency-checking" (deliberate movements to test effects on
a contingent image such as a mirror reflection or real-time television image).
In contrast, behavior with live, unknown dolphins is hyperactive and open
mouth behavior is usually frenzied biting. Since television-directed behavior
is generally different from social behavior with real dolphins, and includes
what appears to be contingency-checking behavior, we conclude that it is
unlikely the dolphins are mistaking their television images for other dolphins.
This suggests that they recognize the images as themselves.
Apparent Social Behavior with Self-View Television.
Of the twelve dolphins exposed to self-view television, only one treated
his television image the same way he interacted with real dolphins. This
was Kamalii, who engaged in intense social behavior in the underwater barred
gate control test (Fig. 3A). He had been with adult male dolphins for most
of his 18 years at Sea Life Park. Two days after the control test he was
exposed to a mirror for two hours. Seven weeks later he had self-view television
for an hour and a half. He acted calmly with the mirror, apparently playing
with bubbles and body motions (Marten and Psarakos, 1994). He was calm also
with the self-view television, coming up with a new behavior: opening his
mouth and curling his tongue (Fig. 3G).
After he had been established with his new female companions for six months
(with no more television and no more mirror exposure in the meantime), he
had 15 more self-view television sessions: 22 hours spread over 7 weeks.
In the first session his reaction was violently aggressive: he rammed the
television window with his head and engaged in intense, aggressive open-mouth
behavior and vocalizations, with his body oriented perpendicular to the
window. Over subsequent sessions, starting with session four, this apparent
social behavior gradually changed to what appeared to be the most elaborate
contingency-checking we've seen: twitching, undulating his body fat, spinning
and jerking his body, blowing bubbles and biting them, regurgitating fish,
and moving his tongue outside his mouth. Kamalii's apparently aggressive
behavior with the television alerts us to the fact that the results of self-recognition
tests can depend not only on the individual's mirror experience, but also
on internal state, and/or recent social history.
Self-View Television Compared To A Mirror
All twelve of the dolphins we exposed to the mirror spent more time in front
of it than the self-view television. However rhythmic head and body movements
were more common and exaggerated in front of the television: more repetitive
head and mouth movements, greater excursions of movement, and more cycles.
The smaller size of the television image may elicit more pronounced forms
of contingency-checking than the mirror does. In Kamalii's case of apparent
social behavior with the television (but not the mirror), the small size
of the image may have been recognizable as a dolphin but not as himself,
and thus instigated a social reaction. The lack of social behavior by all
other dolphins tested in front of both mirror and self-view television is
in striking contrast to apes, who have an initial period of social behavior.
It is likely that the reflections from underwater windows in the dolphins'
tanks may provide them with enough exposure that they are not naive to their
mirror reflections.
Development of contingency play. Early development of contingency
recognition is another similarity between dolphins and humans. The earliest
age we saw contingency play was 1 1/2 years, in Maui, the youngest individual
we observed. The dolphin babies' greater interest in mirror mode television
over video playback of themselves and others, however, is different from
human babies, who give greater attention to non-contingent playback of others
over either contingent or non-contingent television of self (Lewis and Brooks-Gunn,
1979). Human babies also commonly play "peek-a-boo" games with
contingent television (getting in and out of range of the television camera),
which did not occur with the dolphins. The other most common human baby
behavior with contingent television is making faces -- analogous, in our
opinion, to dolphin head and mouth movements. Overall, the results from
the dolphins are suggestive of self-recognition in adults (but do not prove
it), but are mixed for the babies.
Window Reflections As Possible Mirror-Like Experience, And Control Tests
Our mirror mark test results indicate that the dolphins are probably not
naive about their reflection. Dolphins in tanks with windows are most likely
already experienced with their reflections in the windows. We have documented
this by photographing our reflections in the windows of the tank. There
is a reflection of varied quality depending on time of day, although never
as good as a mirror. To the extent that a dolphin is familiar with its reflection
from the windows, its image in a mirror or on television is not entirely
novel. If this is the case, then perhaps a control test for television or
mirror testing of self-awareness should include recording the dolphins'
response across a barrier to a known dolphin. There is no formal data on
this topic, however when dolphins at Sea Life Park are separated by a barred
gate after shows, they often become more aggressive through the gate than
when they were together. In addition, in our control test with two adult
males (Keola and Maka), Keola also interacted with familiar dolphins through
an underwater barred gate. His interactions with them were frenzied and
aggressive. This type of behavior contrasts sharply with his behavior during
mirror mode television, or in front of a mirror.
The Role Of Perception, Motion, Vision, and Sound In Self-Recognition
Perception. The television tests are based on the premise that dolphins
perceive television like people do: as a representation of reality. Herman
et al. (1990) found that dolphins responded to artificial language command
gestures on an 11.5 inch television. To test if dolphins treat images on
their television as a representation of reality in the absence of food reward,
we played some of the dolphins a videotape of their trainer feeding them.
Keola, Hot Rod, and to a lesser extent Tinkerbell, appeared to try to "catch"
the television fish by opening their mouths each time a fish was thrown.
After doing this for about a minute they left the monitor and went to the
small tank (where they were accustomed to being fed). In one instance when
Hot Rod was watching the video it came to an end with the trainer packing
up her fish buckets and leaving; Hot Rod rushed to the small tank. These
results demonstrate that television may represent reality for dolphins.
Motion. Dolphins are predators and are attracted by motion. They
often ignore something until it moves. The dolphins' first reaction to mirror
mode is to move, or contingency-check. Primate researchers seem to think
that their subject recognizes itself visually. In dolphins the role of movement
could outweigh visual form, and contingency-checking may be necessary for
self recognition.
Vision. Dolphins have good visual acuity (Herman et al., 1975). (See
Dawson, 1980, Nachtigal, 1986, and Madsen and Herman, 1980 for reviews.)
Herman et al. (1990) found that dolphins responded to human artificial language
gestures, and even degraded versions of these, on an 11.5 inch television
placed 40 cm from their underwater window. As for visual field, the dolphin's
eyes are more laterally placed and directed than in primates, so sometimes
the dolphin is seeing its target with one eye. It is possible that side-to-side
head movements are actually examination of the target with alternating left-right
visual fields, as Povinelli found in elephants (personal communication),
rather than contingency-checking.
Sound. The dolphin's primary sense for complex processing is sound,
and this should not be overlooked when exploring self-recognition in these
animals. Since echolocation clicks are reflected efficiently by the air
side of the underwater window, according to the dolphin's sonar there is
no dolphin where the television is. However, the reflected sound could be
interpreted by the dolphin as a vocalization coming from a dolphin located
behind the window. Furthermore, sonar clicks, after they have reflected
off the window, could reflect off the dolphin, back to the window, and then
back to the dolphin, containing a sonar image of itself. Gish (1978), working
with bottlenose dolphins in two tanks with an acoustic link, found similar
behavior in the acoustic mode to what we have found in the visual mode:
prolonged aggressive interchanges through a "fence", mimicry,
and recognition of the difference between echo of self and playback.
Self-view television behavior differs from real social behavior (controls)
and from reaction to playback of self, and is characterized by what appears
to be contingency-checking behavior. These findings, plus the results of
the mark and turn tests, are consistent with self-examination and not social
behavior. The material presented here, especially when combined with the
highly suggestive results from the mirror mark tests and their controls
(Marten and Psarakos, 1994), makes a significant case for self-awareness
in this species.
This project is a cooperative effort between Earthtrust and Sea Life
Park. It was conceived by Don White and Dexter Cate. Don White's participation
was valuable at all stages. We thank Sea Life Park curator Marlee Breese
and trainers Stephanie Vlachos, Susan Rodgers, Roberta Horne, Keana Pugh,
Rich Nunes, and Carol Chang. We received help and valuable advice from Lori
Marino and Gordon Gallup. Don Griffin suggested the turn experiment. Dave
Hack provided the tank drawing. Oceanic Institute provided electricity.
The research was supported by Mollie Malone, Wendy Grace, the Boudjakdji
Family, the Sarah Stewart Foundation, the Barbara Gauntlett Foundation,
Outrigger Hotels.
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Received May 7, 1993