Where does a dog have to be to teach him to be aggressive towards someone on-command? My boy is coming up to 16 months old and when I tell him "who is that" he will start barking at someone or noises or whatever it is, but it's not consistent, like if he decides someone doesn't need to be barked at, he'll just look at them for a bit then dismiss it as not being a threat, but if we are at home and there is a noise somewhere outside and I tell him that, he'll jump up barking - he automatically barks at the doorbell so that's covered. I'd like to teach him that if I tell him to "act aggressive" that he takes my word for it that the person im referring to should be barked at, rather than let him decide on his own. If someone has a link to any articles or knows techniques to achieve this then let me know - he's a little on the sharp side so getting him to bark at suspicious people isn't too difficult, but someone standing 5ft away from me isn't considered "suspicious", n if he is barking at them, I could release him n know that he's probably gonna run circles around them and act like a goofy puppy rather than scare them away.

You will need a helper to achieve this. You can teach any dog to bark on command without the use of a helper, but you want him to look at a person as a threat. How is he suppose to look at someone as a threat if there really isn't a threat?

What worked with me was as follows - say to the dog the word "SPEAK" while holding a ball aloft and if he barks give him the ball - if he doesn't bark do not reward - it works eventually - I have now reached the point where I hold my fist aloft shoulder height - I say "SPEAK" and he barks - the longer you hold your fist up the longer he will bark - it'll take time - but try it on a daily basis and within a few days you will have cracked it....

Again, you are teaching the dog to speak(bark) on command. This differs dramtically from teachting to "watch" someone on command, or what term you use for you dog to show is feeling threatend. Dog traing come spot the difference out form a mile away. I personally think any thug on the street can too. Most people know when your dog is barking or when he means business. I might be along on this one, but its just my observation, and now how I would train to reach mikes goal, if I am correct if having the watch aggressivly on command.