They can detect the 'odd one out' in a set of geometric shapes, and have an affinity for geometric regularity – shapes with consistent features, like squares, as opposed to irregular ones ...

Squares, triangles, circles - these geometric shapes appear everywhere in art and architecture going back all through human history. Geometric regularity seems to be something that the human brain ...

This prevented stress and boredom. Their performance indicates a natural understanding of geometric principles. In order to recognise the odd shape, the birds did not need any further training.