Ducklings are rather well-known for their ability to imprint on someone (usually their mother) or something shortly after hatching. Researchers at the University of Oxford were interested in understanding more about learning and memory in ducklings. Specifically, they wanted to know if a duckling simply remembered what they saw or if they were capable of more complex cognition involving determining whether objects had the same or different qualities.
After hatching, they placed ducklings in an enclosed space that contained either identical or different red shapes attached to a string that moved the objects in circles around the enclosure. Naturally (or rather unnaturally), the ducklings imprinted on the objects and began to follow them. The ducklings were then given a break and placed in an enclosure where they were again exposed to 2 objects moving in a circular path that were either identical or different. This time, however, the ducklings had never seen these new shapes before. What they found was that 32 of the 47 ducklings examined actually began following the pair of objects that matched what they had imprinted on (i.e. same or different objects).
The experiment was then repeated with new ducklings and this time they kept the shape the same but either exposed the ducklings to the same or different colored objects. Here too 45 of 66 duckling began to follow objects with the same relational concept they had imprinted on in the training phase.