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“Dolphins are very intelligent”. Many people believe this
but how do we know how intelligent dolphins are? It’s very difficult to
objectively measure global intelligence in humans, especially when
people come from different cultures, and even more difficult to study
what animals know and understand (cognition). Studies must be very well designed in
order to be meaningful; and how much more difficult is it to study
marine mammals that have evolved to live in the very different
environment of the sea where most of their lives are spent underwater?
It’s well known that cetaceans are social animals with wide vocal
repertoires: Humpback whales singing long, complex and continually
evolving songs, and Killer whale (Orca) pods that seem to communicate
using their own ‘family’ dialects are two better known examples. In an
often dimly lit, 3-dimensional underwater environment in which sight can
be of little use, dolphins and porpoises are masters of using sound to
navigate, find and catch prey, and communicate with each other: they can
even use their SONAR to find fish hiding for safety under the sandy sea bottom. Although
dolphins can see well in air and underwater if the visibility is good,
taking instructions from alien humans with strange arms and legs and
very expressive faces must be challenging, and yet, many dolphins
readily learn this skill.
Background
Research on dolphin behavior and cognition has been hampered by
difficulties involved in communicating information between terrestrial
scientists and their aquatic subjects, and vice versa. While marine
mammals rely heavily on their evolved acoustic senses for navigation,
finding prey and for communication, most instructions given by trainers
and researchers to dolphins is in the visual mode in the form of hand
cues, reflecting a pragmatic human preference. A whistle
signal is usually used to signal a correct response to an instruction
before a fish reward is given to the animal subject, and, though a very
effective training tool, a simple whistle not convey complex information.
Dolphins are adept at using a large range of sounds to obtain
information about their environment and to communicate with
con-specifics. In order to study dolphin behaviour and cognition in
greater depth, we plan to utilise this ability to enable 2-way
communication with human researchers in a dolphin-friendly manner. MMRL
has developed a novel computerised interface which can
transmit (underwater) synthesised sounds similar to dolphin whistles,
and also receive and rapidly process the dolphins’ vocal responses. By
training the animals that certain sounds are paired with objects or
actions, or people and other dolphins, and training them to mimic
these sounds, we hope to be able to communicate with our dolphin
subjects.
We are also studying the way in which dolphins encode information within
their natural vocalisations for transmission to other dolphins, in
particular those within their own social group.
Very little scientific work of this nature has been carried out, the
most notable being a substantial series of studies by Professor Louis
Herman and Dr Adam Pack at The Dolphin Institute, Hawaii, USA which
showed that two Atlantic Bottlenose dolphins were able to understand
complex instructions given in the form of novel five word sentences
either by using hand-signed instructions or acoustic instructions. Our
approach is similar to that used by Drs Herman and Pack, but the
computerised system we have developed is theoretically capable of taking
the work further. In addition, this is the first ever study of it’s kind
with Indo-Pacific Humpback dolphins (Sousa chinensis), a species
found in Singapore waters, particularly around the Southern Islands.
Indo-Pacific Humpback dolphins are distributed in coastal waters from
South Africa to southern China and Northern Australia and
relatively little is known about their behaviour compared with the
Bottlenose dolphin (Tursiops truncatus).
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