This also starts the process of the pup learning to give an object for a retrieve (so you get two benefits for one behavior). (servicedogtraininginstitute.ca)
These visual details (overlooked by the rest of us) give objects special meaning and value to them. (discovermagazine.com)
«My preferred method would be to just spell out the word before giving the object every time,» she explains. (animals.howstuffworks.com)