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Cara Santa Maria

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WATCH: The Science of Fear

Posted: 10/31/11 11:05 PM ET


My favorite horror movie is Evil Dead. It's hilarious, ingenious, and it can still make me jump if the room is dark enough and the volume is turned up enough. I'll probably watch Ash and his chainsaw take on his zombified fellow campers tonight while I intermittently pass out Halloween candy to the few neighborhood kids whose parents still let them go trick-or-treating.

Because I am a skeptic, not a lot of things scare me. But if the horror movie or haunted house is good enough, I will try my best to suspend disbelief. In the right context, though, I enjoy being afraid. We all do. That's why Halloween is so fun.

Fear is an emotion that we usually perceive in a negative light. Fear is necessary for survival. If our ancestors had not been afraid of dangerous situations, they would not have known to avoid them, and we would not be here right now. But researchers Eduardo Andrade and Joel Cohen have shown that we can exploit this fear for pleasure if we realize that we are not actually at risk of any real danger. If we measure the risk of harm against our bodies' adrenaline-laden responses, we are often happy to be afraid, simultaneously experiencing positive and negative emotions. Of course, children are sometimes unable to make this distinction, and their fear response to haunted houses, hayrides, and horror movies may be one of genuine fright.

The beginnings of our fear experiences transpire like most other environmental phenomena: through our sense organs. Sensory experiences are transduced into neural phenomena and quickly make their way to the thalamus, a way station for sensory and motor information that sits between the cerebral cortex and the midbrain. After they reach the thalamus, these signals can follow one of two paths: a fast pathway immediately finds its way to the amygdala, and the slower pathway stops for processing by the sensory cortex.

Interestingly, this dual-pathway system for emotional memory encoding was demonstrated long before scientists had a way to measure the exact brain mechanisms underlying it. In 1911, Edouard Claparede was working with a patient who had Korsakoff's syndrome. Korsakoff's is an amnestic disorder characterized by an inability to encode new memories. It happens after years of heavy alcohol abuse damages the mamillary bodies of the hippocampus, a brain structure necessary for forming new memories. (As an aside, if you haven't already read The Man Who Mistook His Wife for a Hat by Oliver Sacks, I highly recommend it. The second story, The Lost Mariner gives a beautiful account of a patient with Korsakoff's.) Anyway, in order to test whether or not Dr. Claparede's patient could form implicit memories, he shook her hand with a hidden pin in his palm and pricked her upon his introduction. The next time he entered the room, although she had no memory of ever meeting him, she withdrew her hand when he extended his. A fear memory had been formed without her conscious awareness.

The amygdala is an almond-shaped structure found deep within the temporal lobe that is responsible for encoding strong emotional memories, like fear (fear-laden memories are specifically encoded in the basolateral nucleus of the amygdala). The sensory cortex is a portion of the brain that receives and processes sensory information, often giving us a conscious awareness that we have seen, heard, smelled, tasted, or touched something. Because the fast fear pathway hits the amygdala first, we often have the sensation of being afraid before we realize what it is that we are actually afraid of.

Once the brain has processed a stimulus and recognized it as fearful, it sets off an endocrine alarm system. This is initiated by a branch of the autonomic nervous system called the sympathetic nervous system, otherwise known as the fight-or-flight response. We experience this whole-body phenomenon when we must be quick on our feet, reacting to a potential predator. Of course, there is no real predator when we are watching a horror movie from the living room sofa, but our sympathetic nervous systems don't know the difference.

During fight-or-flight, the glands that sit atop our kidneys, known as the adrenals, release epinephrine (adrenaline). In addition, our heart rate quickens, breathing shallows and speeds, pupils dilate, and some of us uncontrollably sweat. We also experience two symptoms that are almost synonymous with Halloween: goosebumps and trembling. Goosebumps are actually the result of a phenomenon called piloerection, wherein small muscles in the skin cause our hairs to stand up on end. We feel in on the back of our necks. We see it on our arms and legs. It is thought that this is a somewhat vestigial response, dating back to when our ancestors were extremely hairy. When their hairs stood on end, they probably looked more fierce to predators and could potentially scare them away. We still see it today in our pets, most notably the famed Halloween cat. Also, when we're scared, we literally shake in our boots. This is because our body shunts a lot of that oxygenated blood to our legs so that we can run away as fast as we can. But if we are standing still, that increased muscle tension causes us to shake.

This Halloween, think about what's actually happening to your brain and body when you are shaking with fear!

You can learn more about the science of fear with your kids (or on your own, if you're a big kid, like me) at the California Science Center's Goosebumps: The Science of Fear exhibit, which will also be traveling to cities across the USA.

Happy Halloween!

*In a previous version, the word adrenaline was mistakenly replaced with serotonin. This has been corrected.

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04:22 AM on 11/03/2011
This is an interesting article. Fear does have its attractions, especially the adrenaline rush.The more the dangerous, the more its appeal to me and the drive to do it. Possibly explains the attraction to rollercoaster rides, sky diving and other harrowing activities. Though it's important to know the limits too, release of adrenaline level of fear is fine but avoid at all costs the crapping in your pants level of fear. :)
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HUFFPOST SUPER USER
disappointedliberal
Voter ID = voter suppression
02:35 PM on 11/01/2011
Cara, I have found that things that scare us can usually, but not always, fit into two categories. Using your example of the movie, some movies scare us b/c it represents a danger that we can't escape from. Movies about evil and possession, like The Exorcist, would fall into that category. The other catergory is things that appear very sudden. It is the "jump out and yell boo" type of experience. A movie example of that would be when the skull drops out of the hole in the boat in Jaws. My question is this: Does the body react the same way to the two different types of scary events? Good article. I think you may rekindle my interest in science.
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
04:03 PM on 11/01/2011
I'm so glad to hear it! I want to make sure I understand you correctly. Are you saying that you consider the startle response to be different than a fear of things one actually believes may be a viable threat (i.e., murder, etc., or for some people, ghosts, vampires, etc.)? I wonder if scientists have made a distinction between the two biologically. I would assume that the startle response is a faster sympathetic reaction, while the latter may be more akin to "anxiety," but this is pure conjecture. I will try to find some research on the topic. Thanks for your insights!
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HUFFPOST SUPER USER
disappointedliberal
Voter ID = voter suppression
04:44 PM on 11/01/2011
I think that both events can induce fear. But I am wonder if the body handles the fear the same way for both events. For example, is there a hormone released to counteract the initial release of adrenaline in the startle response since the startling event is so brief? Your conjecture about the faster startle response seems logical and would be consistent with an evolutionary perspective. You need the faster reaction if the startling event is a poisonous snake you just noticed and you need to move, quickly. But it seems like the non-startling event has an added component of the thought or sense that the thing we dread or fear is inescapeable. It seems more cerebral in that we recognize the threatening event and what causes the fear is that we have no control over it. That is absent in the startling event. So, does that lead to a different biological response? I think it is an interesting query but you don't have to research it. I thought if you knew the answer off the top of your head, then I would ask. Thanks.
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jf12
Occupying myself
05:45 PM on 11/01/2011
Drug concentration-response curves vary with rate of administration. In particular, typically the "rush" depends entirely on the rate of change and not the total dose.

A down to earth example of the categories disappointedliberal suggests is hunting dog behavior. I assume from their behavior that when they first scent their prey, e.g. a raccoon, there is a sudden rush, not necessarily involving startle at all. When they tree their prey, the dogs are still excited, probably still the same chemicals and pathways.
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Akshay Singh
Go To Sleep
12:59 PM on 11/01/2011
I guess thats what I felt when i had those panic attacks.
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jf12
Occupying myself
09:36 AM on 11/01/2011
If it's just the adrenaline rush, how to explain your enjoyment of Living Dead while sitting there passively? Maybe it is the memory of, or ghost of, adrenaline rushes that you could be having.
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
01:23 PM on 11/01/2011
We still have sympathetic nervous system responses to perceived fear, even if we aren't in any true danger (i.e., sitting on the couch, passively watching a horror movie).
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jf12
Occupying myself
02:58 PM on 11/01/2011
But there can be a difference. I can feel when the adrenaline rush happens, and it's kind of all or nothing. Yet the same adrenaline-inducing situations can be fun even when adrenaline inducing doesn't happen.
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OliverTwist
Contrarian advocate for truth and justice
07:45 AM on 11/01/2011
NIce.

This ties in with findings that a fast fear response suppresses even the consideration of ideas which register as potentially leading to unpleasant social consequences - a behavior which is exploited by those who use fear and smear treatments to train people to shun certain ideas.
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
01:24 PM on 11/01/2011
Indeed. Fear is an extremely powerful emotion, and that can be easily exploited.
lastpost
see biography
06:58 AM on 11/01/2011
"Fear is necessary for survival."
Doesn’t that depend on what the threat is? Some dangers are better negated by precision, than they are by panic.
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
01:25 PM on 11/01/2011
I meant that in an evolutionary sense. Most fight-or-flight situation required us to either run away or attack, in an effort to save our skin.
03:35 AM on 11/01/2011
Meditation and ethical training can free the mind for rational, logical thinking, acceptance of reality as it is, and self-discipline. This is the path humanity needs to walk if it's to survive.
03:32 AM on 11/01/2011
Uncontrolled emotion has been humanity's greatest enemy since the beginning of the Neolithic Agricultural Revolution. It's been noted that greed and lust, anger and hatred, ignorance and deluded thinking, are the 'three poisons' that taint the human experience and are the source of our problems; I find this to be true. Fear and anger once served a purpose for hunter-gatherers, relatively few in number and spread out over comfortable distances; for a variety of reasons, fear and anger are now spandrels, maladaptive, and threaten to destroy our species and much of the biosphere with us. A program of meditation and ethical training which helps us to recognise and control our emotions is humanity's best hope for survival. Our technological prowess has grown far beyond our maturity.
03:24 AM on 11/01/2011
Great video post Cara! I love how you're getting all this science-ish information out in quite an accessible way. Anyway, this is just a little point (and I may be wrong myself) but you said that having Wernicke's was like being stuck in the past... I think it'd be more accurate to describe a Wernicke's patient as being stuck in the present because no memories are being made...
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
01:29 PM on 11/01/2011
Great point, Sophie! Indeed, Korsakoff's patients often feel as if they have "just woken up for the first time." What I meant by my statement that they are stuck in the past is that most Korsakoff's patients have such extensive hippocampal damage that they experience both anterograde and retrograde amnesia. Therefore, they cannot encode new memories, but they are also generally amnestic for a large period of their life histories. Often times these patients believe that the current year is 20+ years in the past.
researcher
researcher
01:28 AM on 11/01/2011
From a creature meaning animal status, fear is a necessity for survival. As consciousness evolves such as to a human level of consciousness, fear can be much more of a liability then as an asset.

Fight or flight can be very harmful mentally and physically if done on an ongoing basis when no fight or flight response is needed. Fear at a human level is most often due to an unawareness of realty. Exceptions of course as sometimes fight or flight is needed.

This is why from a human perspective fear is most often but not always based in an unawareness of reality.

This is why many spiritual teachers teach awareness awareness awareness so above all seek awareness. Awareness can overcome fear, knowledge seldom does. One is a knowing beyond knowing the other is a knowing status. World of difference.

Being smart is often an example of this knowing status. Above all else the human ego wants to be known for knowing. This is why being humble is a sign of awareness.

Many believe that the fear of nothingness after this physical life ends and that the person attempts to suppress that fear is responsible for many of the neurotic behaviors we see in our society. Exhibiting stoic behavior is a classic example of this suppression.

An example of this suppression is a person always defending himself or herself when challenged that they have no fear of nothingness beyond this life.
12:26 AM on 11/01/2011
Since the title of your column, Cara, is "Talk Nerdy to me", I can't help but ask: since you just gave such a good description of the 'quale' of fear, have you considered whether hylomorphic composition of substances could apply to qualia?

See, it IS possible to "talk nerdy" while talking about philosophy instead of about science;)
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HUFFPOST SUPER USER
Johnagain
WTFWJD?
08:42 AM on 11/01/2011
Except that terms like 'qualia' and 'hylomorphic composition of substances' stray into the territory of unsubstantiated nonsense, while science is verifiable, testable, measurable. In other words, real.
07:04 PM on 11/02/2011
Far better philosophers than you even in this centurye agree that neither are even close to "unsubstantiated nonsense". You reveal your ignorance with this unscientific objection.

BTW: lots of things are "verifiable, testable, measurable" without being science at all. Once again, you reveal your ignorance.
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Aladdin Sane1
Remember what the dormouse said...
11:45 PM on 10/31/2011
Well, I couldn't find much scientific in the encyclopedia article on Halloween. Just the bit about agriculture, "festivals of harvest time."

"Much like Day of the Dead celebrations, the holiday has origins in Christianity, as well as festivals of harvest time and festivals honouring the dead, particularly old Celtic and Druid ones."

http://en.wikipedia.org/wiki/Halloween

Some Pagans might consider this bit as scientific, not sure:

"There was also a sense that this was the time of year when the physical and supernatural worlds were closest and magical things could happen."

http://en.wikipedia.org/wiki/Halloween#Pre-Christian_influences
11:34 PM on 10/31/2011
Why love fear? People get addicted to their own adrenaline & other hormones -- addicted to emotional drama. TV news plays off of this, often, using high drama presentations.
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JimNast
All the snark that fits in print!
11:30 PM on 10/31/2011
Epinephrine is produced by the adrenals from phenylalanine and tyrosine. Serotonin is produced in the CNS from tryptophan. While both are monoamine neurotransmitters, they are not the same.
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Cara Santa Maria
HuffPost Science Correspondent
12:10 AM on 11/01/2011
Serotonin and epinephrine are not the same at all!
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JimNast
All the snark that fits in print!
01:13 AM on 11/01/2011
So this must be a misprint?
"During fight-or-flight, the glands that sit atop our kidneys, known as the adrenals, release epinephrine (serotonin)."
11:11 PM on 10/31/2011
that was fascinating. I enjoy this video-chat a lot. Much better than reading. Suggestion: you can add the names you mention on your future videos to the video while talking about the people you quote. Also book's name and others.
I love the video plus you are adorable so is a win-win for me :)
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HUFFPOST BLOGGER
Cara Santa Maria
HuffPost Science Correspondent
01:31 PM on 11/01/2011
I'm not sure what you mean. If you read the written portion of the blog below, you will see that the names of authors, books, scientists, and studies are written out with provided links. I hope that helps!