THE INQ REPORT: Stop Right There!
GAH! FREEZE! A recent study may have figured out what makes us freeze when startled, the classic deer-in-the-headlights response. It turns out the key is the neurotransmitter called serotonin.
Working on flies, the scientists found that when they were startled, serotonin acts like an emergency brake. They think the pause is important because it allows the fly's nervous system to gather the information about the stimuli that caused the sudden change, and decide how to respond. Since humans also have serotonin, the finding may apply to us as well, though more research needs to be done. You can find the whole study here.