Dog training tip o' the day: Extinction & extinction bursts
Extinction refers to the process of no longer providing reinforcement for a behaviour and in the absence of reinforcement a behaviour will cease. For instance, if Pavlov stopped offering meat powder after sounding the tone for a period of time, the dogs would cease to salivate since the association between the tone and the food is no longer being reinforced. This is why ignored behaviours often stop -- the dog is no longer being reinforced for offering them.
However, some behaviours are self-reinforcing, and therefore very difficult to extinguish. For example, a dog often finds barking to be a pleasurable response to various stimuli (barking is FUN!) so even if you ignore a barking dog they're very unlikely to stop this behaviour since they're reinforcing it themselves. That's not to say that you can't train a barking dog to bark less, but it requires a different approach than to ignore it. You need to find and stop the source of the reinforcement while rewarding an alternative behaviour instead.
Then there are extinction bursts. If a dog no longer receives reinforcement for a behaviour, they will increase the intensity of the behaviour in an attempt to earn the reinforcement once again. If the behaviour is still not reinforced after this more fierce series of attempts, it will become extinct.
You can also use the increased intensity of behaviours during extinction bursts to improve them by riding the crest of the burst and reinforcing when the dog is still fervent in its response. We use this to improve hand touch or targeting behaviours and more.