What is "contrafreeloading"

Contrafreeloading is observed behavior in most animals that when offered a choice between food provided or food that requires effort, the animal prefers the food that requires effort.

The term was coined 1963 by animal psychologist Glen Jensen. In his original study around 200 gerbils were given a choice between food in a bowl and food dispensed by a foot pedal. The gerbils preferred the food from the foot dispensed device. Similar studies by Jensen and other researchers have since replicated his findings with gerbils and other animals including mice, rats, birds, fish, monkeys and chimpanzees. The only animal that didn't display similar behavior was domesticated cats, which prefer to be served.