Epinephrine and norepinephrine, which are neurotransmittors, play a large role in converting short-term memories into long-term Memory. They are released when you subject yourself to physical or emotional stress. Some scientists believe this is why you can remember massive details about a car wreck, or why you don’t need to write down the phone number of someone you find very attractive.

Hence, to lock in the memory of audience attendees, the speaker must do something dramatic.