So, for the behaviorist, there are three main learning mechanisms that are intended to explain everything we come to know about the world and the first I could describe pretty easily,, it's called habituation. A behaviorist might define habituation as a declining tendency to respond to stimuli that are familiar due to repeated exposure. That's just a fancy way of saying that, we get used to things, we might react strongly to something that we experienced for the first time, but if we experienced over and over again, we'll react less strongly. So, we become used to the ticking of a clock, or traffic noise, or trains. If in the middle of my lecture I was suddenly go boo, you might startle. But, if I go boo, and then did it again and again, they won't bother you anymore. You become used to it. This turns out to be an incredibly useful psychological mechanism, because what it does is, it keeps us focused on novelty. Something that's been in an environment for awhile, shouldn't capture our attention as much. We've already registered it, we've already thought of it. But, something that is new could be important, and could be dangerous, and so it was worth attending to. When I was a teenager, I worked in a sheet metal factory for a long period and it was incredibly noisy, and sparks flying, and machines moving, and at the beginning, all of these captured my attention, but pretty quickly I grew to become used to it. But, if something new happened, the new noise, or a machine moving in a different way, it would capture my attention and it should. Because it suggests that something different is going on. Similarly for any of us dealing with our environments, something new should capture attention, something old less so, because we already know about it. It turns out habituation isn't extremely important learning mechanism. Without it, I'm not sure how we could survive in the world. We're going to discuss it in the next lecture on developmental psychology in somewhat of a different way, looking at its role in experiments that psychologists have invented to explore the minds of children and even babies.