Here is a small video of a dog doing amazing stuff. It's interesting how he can do such small details. I wander if a trained dog really understands what he is doing. Is he self-aware?
The most successful form of training combines positive reinforcement (follow a desired behavior with something worthwhile to the animal and the behavior will increase) with negative punishment (withdraw something the animal wants when it performs undesirable behaviors).
Service animals, such as assistance dogs, Capuchin monkeys and miniature horses, are trained to utilize their sensory and social skills to bond with a human and help that person to offset a disability in daily life. The use of service animals, especially dogs, is an ever-growing field, with a wide range of special adaptations.
In the United States, selected inmates in prisons are used to train service dogs. In addition to adding to the short-supply of service animals, such programs have produced benefits in improved socialization skills and behavior of inmates.
Training must take into consideration the natural social tendencies of the animal species (or even breed), such as predilections for attention span, food-motivation, dominance hierarchies, aggression, or bonding to individuals (conspecifics as well as humans).