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Innate fears, learnt fears, and unlearning our fears.

Have you seen babies play with candle fires? Or attempt to cross the road even though there are moving vehicles? An alarming number of them don't seem too afraid. But once they have understood the danger, the fear stays with them throughout life.

Conversely, the number 1 fear around the world is either public speaking or spiders (depending on which survey you refer to). Again think about this: are babies scared of public speaking? Well, how can they be? They have no idea what is public or what is speaking! Haven't we all heard of babies blabbering loudly on a train or plane full of strangers? 

We also know people who just seem to have the weirdest fears. I know a guy who is fearful of wet-tissue. And have you seen people screaming in fear while watching others on a roller-coaster? 

So how do we develop our fears? And is it possible to grow out of them?


 

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It turns out that there are different levels of fear.

 

There are some fears that seem innate, i.e. every human being has this fear when born. (You would appreciate that innate fears are not easy to test. Few ethics boards will approve experiments putting babies into a brain scanner and potentially scary situations.)

So far, the list of innate fears is a very short one. One widely accepted innate fear is a sudden loud sound. At all ages, a sudden loud sound causes us to feel fear - this is true for a newborn baby, it is true for an adult watching a horror film, who might even expect a loud sound, and yet still jump a little when it comes. 


A second but more disputed example is a fear of falling (note: not a fear of heights - but of falling from a height). This is shown in a visual cliff experiment (above). A baby is put on a chequered surface. The surface extends onto a piece of glass that covers a second chequered surface down below. As you can see from the picture, babies stop at the edge of the glass and do not dare to crawl across. They show some signs of discomfort, indicating some fear they would fall through (this also shows that babies are born with a sense of physics). The disputes lie in how strict the criterion for innate fear is - every human being must have the fear. Crucially, fear isn't always easy to observe. Sometimes fear is disguised by puzzlement or curiosity.

 

Increasingly, what we realise is not that people are born with certain fears, but we demonstrate "prepared learning". Almost all fears are learnt. But we learn to fear somethings far more quickly and easily. 
 

Snakes are a great example. Let's say a baby has never been out of the house and has never seen either a flower or a snake before (whether in real life or through a picture). You bring the baby out for the first time and there on a patch of grass is a flower and snake lying still. How do you think the baby would react? 

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Even though the baby has never seen either, almost all babies will have no fear of the flower but quickly develop a fear of snakes, a combination of their own sensing (this thing looks odd, its features look a little threatening) and their reading of the reactions of adults around them. However, there are some babies who never develop a fear for snakes, instead befriending them and keeping them as pets - you can find several examples of these on Instagram.

 

Why does this happen? Ancient wiring - the collective experience of all past generations seem to pre-empt us to be more sensitive to certain things. However, this predisposition can be altered by one's own personal experience - perhaps a visit to the reptile sanctuary with a really good guide, or a relative that happened to have a very gentle snake. 
(Interestingly, scientists working with Rhesus monkeys have been able to condition them to fear flowers and not snakes)

This point on "prepared learning" - our inclination to fear certain things, is an important one, as we will see in our chapter on racism. 

 

Next, we move on to fears which are much more individualised, with a learning component that is obviously from personal experience. Joseph LeDoux demonstrates this through a simple experiment with rats:

  • Expose a rat to an innate fear - say an electric shock. What happens? The amygdala (part of the brain responsible for fear, anger, anxiety, and aggression) activates, and we observe the usual - heart rate and blood pressure goes up, the expression changes, it releases stress hormones, etc.

  • Now suppose before an electric shock, we expose the rat to a ringing tone. So every time the tone comes on, you shock the rat.

  • What happens? When this is repeated several times, the rat becomes conditioned to fear the tone. Just the tone alone causes the amygdala to trigger followed by the usual physiological reactions.
     

Great - this seems pretty obvious but the neuroscience behind it is interesting. It turns out that our amygdala has 2 distinct parts.

 

The first is the central amygdala that we have become familiar with - this is the part of the brain that triggers upon fear, anger, anxiety, and aggression - causes us to feel emotional. But there is a second part of our amygdala - the basolateral amygdala. (If names are a turn off to you, the name is not important, the function is).

 

The basolateral amygdala is a learner; it learns new fears through stimulus, either from the environment or other parts of your brain​. When these new fear stimuli are first received by your basolateral amygdala, it doesn't immediately register fear. But over time, the neurons that are tagged to this particular stimulus start to build a strong network of synapses with neurons in your central amygdala, eventually gaining the capability to trigger fear. 


When the rat first hears the tune, the tune only registers in the basolateral amygdala. The rat is not fearful of the tone, only the shock. But over time, the association between tone and shock becomes so strong that the network between the basolateral and central amygdala is established. Eventually: 
 

  1. The rat can be fearful just by hearing the tone alone. Fear of something happening can trigger even if that something never happens.

  2. The network between the neurons in the basolateral amygdala and the central amygdala can become so well established that the rat becomes more fearful of the tone than the shock. We can become more fearful of something happening than the fear of that something itself

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Think about some of the fears we have in life. What exactly causes the fear? Is it actually doing something that scares us? Or is it the thought of it that scares us? Because the thought is merely the tone, the association. But if we become so fearful of just the tone, we might never try something, even if there was no shock. 

One last point:

How do we overcome our fears? How do we learn that something or someone isn't quite as scary as we had initially thought? 

Remember how we learn new fears, as we covered above? Neurons in your basolateral amygdala become sensitised to a particular signal, which then triggers your central amygdala.

 

Now what happens when a rat is constantly exposed to the tone, and there is no shock? And this happens 100 times, 1,000 times? Soon, the rat learns that the tone does not by itself cause any harm. This causes another group of basolateral neurons to register - when you hear this tone, it's ok, there's nothing to fear. 

Neurobiologically, what happens is that when the tone plays, 2 separate groups of neurons start to get active. The initial group that learnt the fear, and the second group that learnt not to fear. The second group works to inhibit the first group from triggering a signal. This seems really weird - as if different parts of your brain are in competition with one another. But this is precisely how your brain works in many areas. Neurons don't just fire when there is a stimulus. Some neurons fire to prevent other neurons from firing. 

Over time, because the tone no longer leads to any pain, the first group of neurons weakens (the neurons themselves fire less readily; concurrently the synaptic network becomes less active, with some synapses dying out - if this sounds a bit alien to you, check out our page on neurons) while the second group becomes more established. The effect is that with enough time, you no longer feel fear.

There are a few major takeaways from this:

  1. You don't passively forget your fears. You actively learn that something isn't fearful.

  2. In this case, it's easy for the rat to learn that there's nothing to fear. The rat can physically experience if there is a shock or not. It's not quite so easy for many of our fears, which are not so straightforward. Unlike the rat, we don't know if there's really something to fear if we never dare to try something new. Or because trying something new is always uncomfortable, we convince ourselves that our fear is justified, we should avoid trying anything new. A good way for us to tackle the possibility that our fears are self-manufactured is through fear-setting - an exercise from Tim Ferriss which I highly recommend

  3. Your brain is plastic - a term in neuroscience that means that it can be shaped and re-shaped. What used to trigger a big reaction can over time weaken until it no longer triggers. Conversely, you can learn to become more reactive to certain stimuli. You can unlearn old habits and learn new ones. You can change behaviour and personality. Your brain is very changeable

  4. While it is a new group of neurons in your basolateral amygdala that triggers to learn and unlearn fear, the basolateral amygdala doesn't work alone in this. The group of neurons which learns that something is not as fearful as original thought gets its inputs from another part of your brain - your pre-frontal cortex. Read more about the interaction between emotions and rationality here. 

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