Once
he understands what his mom is willing to pay for and voluntarily starts to
perform the behavior on his own without needing to be told to do it—that’s
when and only when she should add a cue.

If it seems totally counterintuitive at first to add the cue last, think of it
this way. Imagine somehow that you grew up so far away from modern cities
that you’ve never once in your life seen a traffic light, but now your family
just moved back to civilization and today is your very first driving lesson.
Unfortunately, however, your instructor only speaks Chinese and so is unable
to tell you what to do in any way you can understand. You’ve never been in a
car before and have no idea even how to work the breaks, gas pedal, door
locks, anything… And right then you look out the window and notice a
strange light turn from yellow to red to green way up high on a metal pole
across the street. What on earth is that all about? You wonder….
Until you have at least learned the mechanics of how to make the car
go, that flashing signal holds very little significance. Similarly, when we tell
an untrained dog over and over again to