As a personal protection dog, the Dobermann was originally bred for these traits: it had to be large and intimidating, fearless, and willing to defend its owner from attackers (especially other guard dogs), but sufficiently obedient and restrained to do so only on command. These traits served the dog well in its role as a personal defense dog, police dog, or war dog, but were not ideally adapted to a companionship role. Today's Dobermanns are known to have a much more even and good-natured temperament, as well as extreme loyalty, high intelligence, and great trainability. The personality of the Doberman Pinscher is known to be unique. There is a great deal of scientific evidence that Doberman Pinschers have a number of stable psychological traits, such as certain personality factors and intelligence. In regards to Dobermanns attacking owners, it is rare and usually in the case of overdiscipline. Dobermanns accept physical punishment to an extent. However, when they consider it to no longer be punishment, but an attack on themselves, they will defend themselves.