Alright, so when we're looking at an EEG, we consider 2 things: We are thinking about the frequency of the waves and the amplitude. So, thinking about frequency, this is basically just the number of wave cycles per second, okay, or per some unit of time. And when I say wave cycle, what I mean by that is basically going from the bottom to the top and then back down to the bottom again. So you can see here, assuming that this is taking place in one second, that's only one unit of time, we have a lot of wave cycles happening here.
So this would be a very high-frequency wave. You could also think of this as basically how many peaks do we see within that one unit of time. Obviously, here we have a lot of peaks happening, so this is a high-frequency wave. Whereas down here, you can see we really only have 2 wave cycles happening, or 2 peaks happening, within that unit of time, so this would be a very low-frequency wave. And frequency basically indicates different states of brain activity.
So, for example, we can use it to give us information about the level of consciousness that a person is in, or the different stages of NREM sleep, and you'll see the different stages will have very different frequencies that kind of easily tell them apart. Now, we're also going to be thinking about amplitude, and this is very similar to what we learned about in chapter 4 on sensation and perception when we talked about light waves. So basically, amplitude is just going to be the height of the waves. And so this wave here would have a high amplitude because it's very tall, and then this wave down here would have a lower amplitude because it's short. That one is pretty easy. So amplitude is essentially indicating the strength of the brain activity that we're seeing.
Alright, so when we're looking at our EEGs, we're going to be considering frequency, the number of wave cycles that we are seeing within a unit of time, and we're also going to be considering amplitude or the literal height of the waves. Alright. So I'll see you guys in our next one to actually get into those sleep stages. Bye bye.