system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how our brains notice when something has changed?

For example, if I go into my room and something is moved, my brain will unconsciously realize and bring it into conscious awareness that something has changed. How does the brain detect these changes and decide it’s important enough to bring to awareness? What processes are happening when we notice changes?
gpt
The brain runs a LOT of processes sub-consciously, that is, you are not even aware of them going unless some of them turn up something that the brain thinks should be brought to conscious attention. The brain has a mental picture of your room stored for reference, and when it sees something has changed, it will sound an alarm bringing this fact to consciousness, because it’s pretty important for safety reasons, obviously.