Your mind works on different levels at the same time. Responses to danger (and sexual attraction) happen much more quickly than can be explained by cognition. There is a part of your brain, that doesn’t have access to language or consciousness that can identify scary snakes (and pretty girls) faster than your conscious mind could identify them.

Brain-scans have found that the conscious fear response isn’t a reaction to the stimulus, but rather it’s reacting to your sympathetic nervous system freaking out. The part of your mind that sounded the alarm is invisible to you.