Carrots will suffice: scientists have named the best method of dog training

As it turned out, punishment has an adverse effect on animals' psyche.

An international team of researchers led by the Portuguese biologist Anna Catarina Vieira de Castro conducted a study to find the best method for training companion dogs. 92 dogs from two kennels took part in the project: one animal group was motivated by playing or treats, with physical force and screaming applied in the other one.

The researchers tested the animals’ saliva to measure cortisol levels, also called stress hormone. Three more tests were performed after a 15-minute workout. This helped  establish which of the dogs felt stress during the exercises. The researchers also analysed the animals’ behaviour to assess their mental state.

The findings were predictable: the animals from the kennel where screaming and rudeness were applied were more nervous with high cortisol levels detected in their saliva. The well treated dogs turned out to be calmer.