Crows in a lab were able to distinguish shapes that exhibited right angles, parallel lines, and symmetry, suggesting that, ...

After the birds understood this game, the researchers started showing them sets of shapes that included squares, parallelograms ... know is whether or not "with these quadrilaterals, they could ...

parallelograms, or irregular quadrilaterals. The crows might see, for example, five perfect squares along with one four-sided figure that was just slightly off. What the researchers wanted to know is ...