Jon Krause
It is hard to tell if a chicken is an optimist. After all, you can’t ask it if a glass of water is half full or half empty. But you can repeatedly show it a white card in front of a bowl of tasty mealworms and a black card in front of an empty bowl. Once a chick has learned to reliably choose the white card, you show it a grey card. Chicks that head immediately for this card apparently surmise that it is more white than black, and thus probably contains food – the equivalent of deeming a glass half full. On this basis, …
