In scientific terms, habituation is the process of becoming desensitized or unresponsive to non-threatening stimulus because of repeated exposure to it. That annoying mark on the wall that you stopped seeing; habituation. That annoying clock tick-tocking in the background that you don’t hear; habituation. That horrible odour your colleague left behind that you no longer notice; habituation. That billion dollar frustration which you could easily solve but no longer notice; habituation.
Habituation is an amazing form of learning. It has been shown in essentially every species of animal (Jennings 1906). So it must be essential to every species’ survival and have arrived early in the evolutionary game. It allows us to save energy and reduce stress by not wasting full-blooded survival antics in the face of a gust of wind. It also plays a role in less life threatening things such as when you’re eating, giving you the feeling of being full when you’re not (Raynor & Epstein 2001).