Mental habits become stable and resilient, hard to switch out of, when they are practiced repeatedly. That's the case with piano lessons, pizza night, bicycling, and heroin. It's possible to switch out of one mental habit and settle into another incompatible habit. But you might switch back into the old habit if you're not careful. Because the neuronal configuration that held that pattern in place isn't gone. It's just been "deactivated." Neuronal patterns take a long time to fade -- through a process known as synaptic pruning. And the only way that's going to happen is if other habits are practiced in their place.
Until that occurs, you've got these two habitual mental frames, let's call them drug-wanting and drug-shunning. I referred to these "two yous" in my last post. They're incompatible. One disappears when the other takes over. But it's not hard to switch from one to the other -- either by accident or on purpose.
So here's an example from the domain of optical illusions: the Necker cube.
Take a look at it:
Pretty, isn't it? Now try seeing the face that includes the lower left corner as the outer face -- the face facing you. Easy enough, right? Just stare for awhile. Get used to it. Then imagine a different orientation: imagine that that face is actually at the back, and the front face is the one pointing up and rightward (and including the top rightmost corner) rather than down and leftward. Can you do it? It might take a while, but if you blink a few times and/or move your head around, you should get it. But it's delicate -- like early recovery. Blink again...and your former interpretation might spring back to mind, making the second interpretation highly effortful once more.
Of course these two "interpretations" of the structure of the cube are incompatible. They can't coexist. Just like the you who eagerly anticipates getting high can't exist at the same time as the you who is in control, centered, and connected to the future. These two you's are incompatible. But they can switch. So watch out!
A single population of neurons can represent both versions of the Necker cube. It's just that different subsets of these neurons are switched off (inhibited) and switched on (excited) for each interpretation. It's the same with addiction and recovery, which, by the way, are not two different processes but overlapping phases of the same process.
So let's say you have two interpretations of your drug of choice: cocaine-good and cocaine-bad. A different pattern of activation on the same population of neurons will produce one or the other version. And the two versions can easily switch, as the activation of the neurons shifts, due to....well, due to the way you're feeling, the way you're thinking, how much you slept last night, whether or not your dealer just called, whether you had a coke dream recently, whether you had an argument with your girlfriend, whether you just got a raise at work...or lost your job. Or maybe just the psychological equivalent of a few blinks.
In some ways addiction is very complicated. But in other ways, it's pretty simple. Mental habits can be considered, reflected on, worked with, played with....and they can ultimately be controlled -- with practice. But they can't be controlled perfectly.