They think in images, not actual sounds or anything, basically when deaf people are talking in their mind they see a person doing the hand language, or they see the words as written in a book
That's right. Also, blind people can actually visualize things in their head though they have never seen before. Because blind people can feel vibrations and objects, they can have "mental maps" of things in their heads. As for deaf people, they either visualize things or simply think in a process-like way. You don't always have to think in a language. Animals don't think in a language, they simply experience emotion and make decisions.
I thought of some more questions...
1.) Explain what the colour blue looks like
2.) If our brain flips images upside-down, then upside-down in our view is right side up. In our brains view, does gravity push things upwards?
3.) Our brain converts light into colour. If we all see colours differently, then how would we find out?
1.) This is a very good question. Historically, and throughout every society in the world, blue is the last color that people came to recognize. You may have joked that old people lived back when the world was black and white, but there is actually some truth to it. Before you can call a color a color, you have to identify it as different, which is harder than you might think. This is evident in the Bible, where the colors black, white, and red are mentioned dozens of times, whereas the colors purple, green, yellow, and blue are hardly mentioned at all. In general, the process of recognizing colors follows this sequence, regardless of the society: Black, white, red, then yellow/green, orange/purple/pink, then blue.
But how would you describe blue? Well, the closest thing is actually white, as far as I know. I remember reading a while back about an experiment in which a young child was taught every color of the rainbow except blue, and then around age for or five was asked what color the sky was, and the child replied "white." There isn't a whole lot of science to back this up, but I'd be willing to bet our ancestors would have said the same thing. I still don't see why blue is so difficult to comprehend.
2.) I think our brains view gravity as more of a law of physics. The way we comprehend things is based on what we see and process, so I would say no. In fact, I think our brain flips the image long before we process it.
3.) This is a very good question, and it's definitely not easy to answer. The answer is that people do see colors differently, and we can use some visual tests to diagnose different types of color blindness. However, to find out if two people see green exactly the same in their heads is nearly impossible. Color is an ineffable quality, meaning that it is too complex or personal to describe.
The same thing could be said about pain. The way I experience pain and the way you experience pain could be totally different. For me, pain feels like my flesh is being squished together if it is over a large area. However, when I experience pain in a very small location, (such as when you get a hair pulled out) I feel hot boiling pain on the point which should be in pain, as well as another random point on the surface of or inside my body, as if each point has its own twin point. It's very strange and I don't know if anyone else feels pain like that.
Back on topic, I think the only ways to find out if people experience color the same way are either to do visual tests and see if they say certain colors are similar or not, and to do MRI scans and stuff like that.