What Is The Scariest Thing?

Given below is the summary of the above video:

1.  Everyone's scared of something. Even a new born's mind has got certain innate aversions due to evolutionary reasons. These are falling, suffocation, pain, isolation, sudden movement, the unknown/abnormal, disease and incapacitation. All of these innate aversions are connected to the person's fear of death.

2. There's a region in each hemisphere of the brain called Amygdala which stores a web of sensations and contexts which scare us. Over the course of one's life, a person's brain associates several experiences with the innate aversions and this accumulation process may develop some new fears e.g. Nomophobia is related to our innate aversion of being alone(isolation), fear of public speaking is related to the fear of rejection(isolation).

3. New fears can be developed in a variety of ways e.g. listening to horror stories, watching other person's reaction to something that scares him etc. The video's host participates in a fear conditioning experiment in which he is continuously shown simple geometrical shapes. The display of purple square is always accompanied with a minor electric shock. This is done repeatedly and during the experiment, the host's physiological reactions are constantly monitored using bio-electric sensors. At the end of the experiment, it was found that the host's body's physiological response to the purple square shape did change from what it was before the start of the experiment i.e. he learnt to fear that shape.

4. Every person's reaction to something is not the same e.g. many people are scared of the dark but as per neuro-psychology, children develop this fear only after the age of 2. Some people are scared of certain sounds, however no sound can scare deaf people. Some of us will be scared by abnormal faces however this fear also does not affect children below a certain age.

5. Horror cinema utilises a concept known as 'category jamming' in which they combine multiple scary elements related to our innate aversions in order to create a big scary impact on a large audience.

6. However, sometimes individuals, due to genetic anomaly, don't have functional Amygdalae. Such individuals are not at all fearful of the scenarios which scare most of the other people. They are biologically incapable to develop any fear. However, in a scientific experiment, it was found that elevated levels of Carbon Dioxide in the air can induce fear and anxiety even in such individuals.

7. Researchers believe that this panic response is caused by the sensory neurons found in evolutionary older parts of the brain like the midbrain and brain stem which control more primal physiological behaviour of human beings.

8. When the researchers exposed individuals having functional Amygdalae to highly elevated carbon dioxide environment, to their surprise, they found that their panic response was less severe than that shown by individuals having dysfunctional Amygdalae.

9. So this has led to the conclusion that functional Amygdalae can inhibit fearful response when the person doesn't feel threatened externally(the subjects were voluntarily participating in the experiment).

10. Therefore, the scariest thing for anyone is:
"Elevated levels of Carbon Dioxide in the blood caused by an uncontrollable external threat."