- Hello there, and welcome back to the Mr. Sinn channel. Today we're going to be going over unit 3, topic four of AP Psychology, visual perception. Every day, we perceive different objects, sounds, and experience different situations. When this happens, we utilize top-down processing and bottom-up processing. 

Top-down processing is when you use prior knowledge to interpret new information. Oftentimes, this new information is familiar to you. And it's not very complicated, while bottom-up processing is when you interpret information that is complex or unfamiliar to you. You process information by taking in the incoming stimuli and organize it as it comes. 

Think of top-down processing and bottom-up processing this way. Pretend you're trying to solve a complex and massive puzzle. And unfortunately for you, the top of the box is missing. So you have no reference as to what the puzzle should look like. What do you do? To start, you'll probably use top-down processing to complete the outer edges of the puzzle. This is because you've done puzzles before, and you'll rely on prior knowledge of puzzles and understand it's fairly easy to start with the edges. 

Once you're inside the puzzle, though, you'll most likely use bottom-up processing to organize the puzzle pieces by colors and try to match different pieces together. Now let's say you found the box, and you can see the completed picture. Now you can use top-down processing on the whole puzzle. You know what the puzzle should look like. And you'll use that knowledge to help you complete the puzzle. This makes it easier to do the puzzle and shortens the amount of time you'll spend on it. 

Our brain uses top-down and bottom-up processing to handle different situations and scenarios that we come across in our lives. This can help us with making decisions and understanding the information that we are taking in. But sometimes it can also cause us to make errors. 

Remember some of those optical illusions that we looked at during our unit 3, topic one video? Part of the reason why they are so effective is because of how we process the information. 

For example, when looking at this image, you probably see the circles. But I bet you also see a cube, even though there is number cube in the image. Our brains are taking in the information we are seeing and filling in the blanks. We know what a cube looks like. And even though there is no connected cube in this image, we can see one. 

Whenever we are familiar with a topic, a stimulus, or content, we are more likely to use top-down processing. This can sometimes cause us not to see errors or mistakes. How many times have you written a paper before, and you proofread it multiple times, but you still did not catch all the spelling and grammar mistakes? When you reread the paper, your brain is autocorrecting the errors without you knowing it. This is known as proofreaders illusion. Your brain is using top-down processing, causing you not to notice the mistakes. This is why it helps to have someone else read your paper as well. 

One last example would be the text on the screen right now. I bet most of you can read this. You're using top-down processing. Even though the letters are not in the correct order, you still can understand what the text is trying to tell you. 

And just like that, another topic review video is done. Now, you know the drill. Answer the questions on the screen. Then check your answers down in the comments section below. Also, consider subscribing and checking out the Ultimate Review Packet. The Ultimate Review Packet will help you get an A in your class and a five on the national exam. It covers all the units and has tons of resources to make sure you can succeed. As always, I'm Mr. Sinn. Thank you so much for watching. And until next time, I'll see you online. 

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