Many fears are caused by ignorance because people are scared of what they don’t know. The reason for this is simple.
When your brain is only given a few pieces of information it tends to fill in the rest of the details by itself.
For example, when you look at a picture on a computer screen, what you are actually seeing is a series of tiny dots. However, because the dots are so small, your brain fills in the gaps and you see it as a complete picture.
A 2005 poll of U.S. teenagers revealed the power that emotion can have in searing fear-filled memories deeply; despite the teens' limited direct experience, terrorist attacks, war, and nuclear war held top-ten berths in a list of fears.
This finding hints at a phenomenon that Hadjikhani and her colleagues study: the contagion of fear. In her research, Hadjikhani has found that humans, like other animals, can experience fear indirectly, the result of another's glance or muscle tensing, or, on a larger scale, that electric connection that turns a milling crowd into a stampeding throng.
People are hard-wired to respond to danger. It's actually an ancient system, often called the reptilian brain, honed over centuries to keep us safe.
We hear a scream and instantly, without conscious thought, our autonomic nervous system sends a signal from our senses to the fear center of the brain, the amygdala.
Hormones such as cortisol and adrenaline jump-start our body -- the heart starts to race, breathing comes more quickly and sweat breaks out. We're ready to flee or fight.