Pigeons' brains are equivalent to that of toddlers', according to the study by researchers at University of Iowa (UI).

During this study, the UI researchers used a computerized version of the 'name game' in which three pigeons were shown 128 black-and-white photos of objects from 16 basic categories- baby, bottle, cake, car, cracker, dog, duck, fish, flower, hat, key, pen, phone, plan, shoe, tree. They then had to peck on one of two different symbols- the correct one for that photo and an incorrect one that was randomly chosen from one of the remaining 15 categories. The pigeons not only succeeded in learning the task, but they reliably transferred the learning to 4 new photos from each of the 16 categories.
UI researchers said, "Our expanded experiment represents the first purely associative animal model that captures an essential ingredient of word learning-the many-to-many mapping between stimuli and responses." Ed Wasserman acknowledges the recent pigeon study is not a direct analogue of word learning in children and more work needs to be done. Nonetheless, the study model could lead to a better understanding of the associative principles involved in children's word learning.
The study appears online in the journal Cognition.
Source-Medindia