{"fact":"Just like humans, crows can get excited and even discouraged during experiments and may need some extra encouragement from researchers.","context":"Especially during the early experiments, the crows often exhibited considerable fear and excitement when shut in the small compartments... it was then possible to confine them... without causing disturbing excitement.","source":"Charles A. Coburn; Robert M. Yerkes, A study of the behavior of the crow Corvus Americanus Aud. by the multiple choice method., 10.1037/h0076090","index":17}