Semantic satiation is what happens when you repeat a word so many times that it seems to lose all meaning. The process behind this is something called ‘reactive inhibition’ – essentially, your brain gets bored with the word and produces a weaker response each time the word is heard, eventually dropping off altogether. I am neither a psychologist or a neurologist, but on the surface this looks like an instance of nerves ceasing to fire when repeatedly exposed to the same stimulus. It’s the reason why you quickly get used to any sort of strange smell (and why you generally can’t smell yourself). The brain doesn’t want to waste it’s resources taking into account a constant feature of the environment, so once something seems to be there to stay, it gets ignored. Any stimulus repeated enough times will eventually fail to illicit a reaction at the neurological level, so it seems reasonable that these effects are visible at the psychological level.

Because of this, any constant feature of your environment will eventually be ignored. It’s this ability that lets us adapt to new situations, no matter how bad (or good) they might be. That horrible job doesn’t seem so horrible after a few weeks at it, and that solid gold house doesn’t seem so amazing after the 100th time you wake up inside it. We get used to things, for better or for worse – pleasure and pain fade over time. What doesn’t fade is desire – our reward circuitry is (I think) decoupled from this, providing a constant need to pursue more no matter how much we already have. This might be why it’s so easy to be greedy – we’re designed by evolution to pay attention to what we don’t have, not what we do.