 Hi, and welcome back to this video course on biological psychology. In this video, video 4.2, we're going to ask ourselves what memory is. So, let's start with a very simple question. Why do we remember? What is the purpose, the function of memory? Now, this is of course a philosophical question and it doesn't really have a right or wrong answer. But to me, I would say the most adequate answer that you can give is that we make memories to predict the future, right? Everything we do, perception, memory, all our cognitive activities at the end of the day having to do with preparing us for the future so that we can, you know, we stay alive, we can breathe, etc. Right? So, I think memory is a way not so much, the goal of memory is not so much to retain the past, but to use the past so that we can predict the future. That's what I would say is the function of memory. So, what is memory? Memory is many things. A lot of things that happen in our brain have in some way to do with memory, just like attention is many things, right? So, it's a multifaceted concept. But in general, any process to encode, store and retrieve information is memory. And there are many forms of memory. And generally speaking, we separate three stages of memory, which we're also going to describe separately in the next videos. So, sensory memory is a brief trace of what you just saw. So, if you see a visual stimulus, for example, for a very brief moment, that visual stimulation sort of reverberates in your visual brain areas. And then we move on to working memory, which is slightly longer lasting. So, sensory memory is a type of memory. It's hardly really memory, I would say, that lasts maybe for one second. And then, if you sort of grasp, mentally grasp one of the things that you've seen, and you rehearse it, you pay attention to it, then you talk about working memory. So, working memory allows you basically to remember a few things for as long as you keep rehearsing them, keep paying, mentally paying attention to them. And then we have long-term memory. And long-term memory is, I guess, what most people tend to think about when they think about memory. It is just the fact that our brain is kind of like a database with a lot of facts and memories in there. And long-term memory is almost like an infinite capacity memory store that allows us to store all kinds of arbitrary information. With that, let's move on to the next video in which we're going to talk about sensory memory.