{"fact":"Crows appear to have a natural preference for solid objects over hollow ones.  In a study where crows had to choose between dropping different objects into a tube, they strongly favored the solid ones from the start!","context":"However, in the hollow vs. solid task, the intercept was statistically significant, suggesting that subjects were more likely to choose the solid object over the hollow object at the onset of the task.","source":"Laura Hennefield; Hyesung G. Hwang; Sara J. Weston; Daniel J. Povinelli, Meta-analytic techniques reveal that corvid causal reasoning in the Aesop’s Fable paradigm is driven by trial-and-error learning, 10.1007/s10071-018-1206-y","index":328}