“…A second reason to believe that cognitive challenges can enhance animal well-being comes from studies showing that engaging in cognitive challenges has been associated with positive welfare indicators, including increases in movement or activity [ 62 , 63 , 64 , 65 ]; decreases in stereotypies [ 62 , 63 , 66 , 67 , 68 ]; decreases in self-directed behaviors such as scratching or feather-plucking that are commonly seen as stress-induced [ 69 , 70 ]; decreases in physiological indicators of stress such as salivary cortisol [ 65 , 71 ]; increases in behavioral diversity and exploratory behavior [ 62 , 72 ]; and the presence of positive affect and excitement behaviors [ 73 , 74 ].…”