Abstract:
Echolocation is one of the important senses in dolphins that contributes to their
perception of the underwater environment. However, many questions still remain
unanswered with respect to the development of their echolocation sense. It is
observed that dolphins can be trained quite fast to perform an object recognition
task. However, it is unknown whether dolphins have to learn to echolocate after birth
or have the innate ability to do so. Here, an indirect approach of studying the
acoustics in a non-neonate dolphin was conducted, to understand the development
of echolocation in dolphins. A dolphin, named Angelo, was trained at a young age to
perform several cross-modal matching tasks. These tasks involved echolocating an
object concealed inside an anechoic box, followed by having to match it visually to
the same object among several alternatives presented in air. The analysis of the
learning curves associated with the dolphin’s progress showed that Angelo
understood the concept of matching-to-sample. Along with the progress of the
training, Angelo was observed to fine-tune some acoustic parameters in the clicks he
transmitted. Both the average click number used by Angelo across trials and the
variance of the mean frequencies of clicks in individual trials decreased as the
training progressed. This fine-tuning of the acoustic parameters by Angelo suggested
that there was learning of echolocation involved.
