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| While wearing eyecups, Tanner still successfully imitates DRC Co-Founder Mandy Rodriguez's "shark" behavior. |
In 2010,
Dolphin Research Center (DRC), a leader in dolphin cognition research, scientifically
demonstrated that dolphins can imitate without using their eyesight.
A recently published follow-up study now not
only reveals that these intelligent marine mammals achieve this task by using
sound, but that they employ a deliberate, problem-solving approach to
imitation.
In the original study, a
dolphin wore soft, latex eyecups to block its vision and then imitated another
dolphin.
To determine if sound was
indeed used to accomplish imitation, for this new study the “blindfolded”
dolphin was asked to imitate a
human’s
movements in the water.
The study,
called
Switching Strategies: A Dolphin’s
Use of Passive and Active Acoustics to Imitate Motor Actions appears in the
online edition of the journal
Animal
Cognition (February 2013).
A video
produced by DRC about the study can also be viewed at DRC's YouTube channel by clicking
here.
“We
had to change the way that behaviors sound to a dolphin to see if that affected
his ability to imitate,” explains Dr. Kelly Jaakkola, DRC’s Director of
Research.
“Clearly when a person moves
in the water, he sounds very different from another dolphin.”
Throughout testing the human modeled a
variety of motor behaviors such as bobbing up and down, swimming while kicking
feet together, spinning in a circle or even swimming like a fish with legs and
feet moving side-to-side.
The dolphin, a
young male named Tanner, successfully imitated the behaviors with a high rate
of accuracy.
Confirming
that the dolphin did indeed use sound was exciting in itself, but how he used
sound was even more intriguing.
During
testing, in addition to visual observation and video recording, the research
team also used a hydrophone – an underwater microphone – to record what
happened beneath the water’s surface.
“When imitating a dolphin, Tanner recognized the characteristic sound of
the behavior, much like people might recognize the sound of hands clapping.
When imitating the less-familiar behavior of
a human in the water, he switched strategies and used echolocation a whole lot
more,” Dr. Jaakkola elaborates.
“Dolphin
echolocation is not typically on.
It
requires a decision on the part of the dolphin to activate it, which shows that
Tanner wasn’t just mindlessly acting.
He
was flexible enough to change his approach to gather the information he
needed.
In other words, he actively
problem-solved.”
Realizing this
provides new insight into the dolphin mind, but the implications are even more
far-reaching.
“Scientifically, studies
like this are really important because so far, only humans and dolphins have
shown this kind of flexible skill with imitation.
But humans and dolphins are separated by
about 90 million years of evolution.
This means they must have evolved these skills separately.
So exploring imitation in dolphins and humans
can teach us not only about each individual species, but also has the potential
to fill in crucial information about why the ability to imitate ever evolved at
all,” believes Dr. Jaakkola.
Dolphin Research
Center’s research continues to add to the world’s knowledge database on
dolphins.
In addition to this study and
its predecessor,
Blindfolded Imitation in
a Bottlenose Dolphin (Tursiops truncatus) which appeared in the
International Journal of Comparative
Psychology (Volume 23, No. 4), DRC’s research demonstrated for the first
time that dolphins can understand numerical concepts and explored what dolphins
understand about hidden objects.
Throughout the years, the center has been
involved in numerous other observational, cognitive, and husbandry research
projects and papers, both on its own and in cooperation with other well-known
scientists and institutions. These
include studies on immunology, DNA fingerprinting, metacognition, language
research, signature whistles, calf independence and others.
