The sensory information is just relayed directly into your brain. One part of it is routed into the cortex, where it's sort of thought about: 'that's that thing, I know that from last time I experienced this', and you can kind of rationalise your way through it. But it also sends a message directly to the amygdala, which immediately triggers the 'fight or flight' response – bang, fire alarm, off it goes, flood the body just in case. It's a survival mechanism.