Experiment Involving 22 Calves

The hole at one end contained milk from a bottle, while the hole at the opposite end contained only an empty bottle and delivered a puff of air in calves' faces. | To gauge optimism and pessimism, the researchers set up an experiment involving 22 calves. | The calves learned quickly which side of the pen held the milk reward. | In the training, each calf entered a small pen and found a wall with five holes arranged in a horizontal line, two-and-a-half feet apart. | Before they started the experiment, they trained the calves to understand which of their choices would lead to a reward.