This ability was previously known only in highly intelligent animals.
A new mother duck is rarely seen without a string of fluffy ducklings following close behind. Their strong bond is formed by a type of learning called imprinting, which causes ducklings to follow around any moving object that they see during a sensitive period immediately after hatching. Usually, the first moving object they see is their mother.
A new study in the journal Science shows that ducklings can not only imprint on objects, but they are also capable of imprinting on concepts.
Newly hatched ducklings were presented with a pair of moving objects that were either the same as or different from each other in shape or color. Because the ducklings saw them during the sensitive period, they imprinted on these pairs of objects. But were the ducks imprinting on the objects themselves, or on the relational concepts i.e. whether the objects were “same” or “different”?
In subsequent choice tests, each duckling could follow either of two pairs of objects composed of shapes or colors that the duckling had not previously seen. For example, if a duckling had originally been exposed to a pair of spherical objects, in the choice test it may have been given the options of following a pair of pyramids (same) or a pair made up of one cone and one cylinder (different).
Even without having seen the specific shapes before, nearly three-quarters of the ducklings (77 of 113) preferred to follow the stimulus pair exhibiting the “same or different” relationship they had learned in imprinting. Their accuracy was high, whether they had originally imprinted on same or different objects, and whether they were tested with shapes or colors.
These ducklings represent the first known case of a non-human animal learning to discriminate between abstract relational concepts without any reinforcement training, study co-author Alex Kacelnik of Oxford University said in a press release.
“The other animals that have demonstrated this ability have all done so by being repeatedly rewarded for correct performance, while our ducklings did it spontaneously, thanks to their predisposition to imprint when very young,” he commented, adding: “And because imprinting happens so quickly, the ducklings learned to discriminate relational concepts much faster than other species, and with a similar level of precision.”
The ability to understand relational concepts may hold adaptive value for ducklings, who are critically dependent on staying close to their mothers.
“Ducks walk, swim and fly, and are constantly changing their exact shape and appearance as they extend their wings or become partially submerged, or even change angle with respect to the viewer,” explains lead author Antone Martinho. “If the ducklings just had a visual ‘snapshot’ of their mother, they would lose her.”
Possessing a library of concepts describing the mother’s characteristics is a far more efficient and reliable way a duckling to identify its mother.
Kacelnik adds: “Most animals will, like the ducklings, need identification mechanisms that are robust to natural variation. A challenge we face now is to identify the processes by which the animals' brains achieve it.”
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