Show scientific proof that these frogs show these emotions please.
I am very familiar with white's, having kept them for years prior to keeping darts. The are not social, but solitary animals. The only time they actively seek others of their kind is to mate. They also do not just live in dense rainforests, but also on the semi arid margins at the edge of the forest.
"Keeping them in a cage all the time without any interaction with the outside-of-the-cage world is cruel". I am assuming this is YOUR opinion and not based on fact. The fact of the matter is, our "outside-of-the-cage" world is truly unnatural for them and adds stress. Provided they are given the proper conditions to live in, they will live a perfectly healthy existence, inside their enclosure.
Also, feeding every 4 days is not an issue. I fed mine weekly and I also know many people who do so as well. Feeding every day is a good routine for US. In their natural habitat, white's will go extended periods of time without eating during the dry season, when food is not as plentiful.
Education is the most powerful weapon we can use to change the world ~ Nelson Mandela