system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can things like optical illusions “trick” our brain, even when you know for a fact what the reality is? Why is “what your brain thinks” not equal to “what you know”?
gpt
Our brain is HEAVILY optimized for pattern recognition and prediction.  It happens without our even being aware of it. 

So when something breaks set patterns that we're used to, that pattern has already been recognized and predicted by our brains well before we get to the point of conciously pondering the issue. 

A lot of our thinking happens without us "thinking" about it at the level of a conscious internal monologue. It's the same place we get gut feelings we can't explain because they happen below that monologue level.