All training is based on psychology & body language, no force is required... even leash training! It's simply more effective & efficient to teach a dog in their native language, body language, rather than trying to teach them how to understand English. ;~}
I have over 30 years experience of handling dogs & over 20 years experience of training dogs. As all my dogs have been rescue dogs I have a great understanding of most behavioural problems many of which can be changed in a surprisingly short time with some understanding & encouragement.