The Science of Fear

Scream from amazoncom
From Scream (1996)














What is your favourite scary movie?

I don’t think I have one, but I did see some very good movies at Celluloid Screams, the Sheffield horror film festival at the Showroom. Watching a horror movie initiates the fight or flight mechanism that is at the heart of fear and at Halloween no less! It doesn’t get more perfect than that, so read on to find out about the science of being spooked.


The neural circuitry of fear starts in the amygdala within the brain which is part of the limbic system. Named after the Greek word for almond, the amygdala is the storehouse of emotions and is triggered by an external stimulus, which in this case is something scary. Joseph le Doux, a neuroscientist at the Centre of Neural Science New York University identified the amygdala’s role in emotional processing, which hijacks the brain circumventing the “thinking” part of the brain the neocortex (Goleman, 1995). Together with the hippocampus which retrieves memories, the amygdala strengthens emotional memories (McIntyre and Roozendaal, 2007). So the greater the stimulus the more the amygdala is aroused, and the stronger the imprint is within our brains, which is why we always remember the moments that scare us the most. Unfortunately, this means that sometimes things that don’t actually present a real threat can be perceived as one. When this happens it becomes an anxiety, a psychological response (Edwards, 2005) which can lead to post-traumatic stress disorder (PTSD) and phobias. Such conditions as PTSD or anxiety can actually be due to abnormal functioning of the amygdala or developmental problems or a neurotransmitter balance or even lesions of the amygdala (Harrison et al. 2015).

The amygdala triggers the hypothalamus which produces the hormones dopamine and corticotropin, and activates the sympathetic nervous system. The corticotropin further activates the pituitary gland to release the adrenocorticotropic hormone (ACTH). As the reward hormone, dopamine gives us the “kick” we get from doing things we like, be it playing computer games, hanging with partners or watching horror movies. But the people that are disposed to really enjoying horror movies (like me) have fewer dopamine receptors than those that don’t. This means they are less able to regulate their dopamine levels getting more of a kick (Zald et al. 2008).

The release of ACTH and the activation of the sympathetic nervous system then stimulate the adrenal glands to produce cortisol and adrenaline, and the eccrine glands in the hands to produce sweat. Although I’m sure sweaty hands is more of an occurrence during first dates and public speaking rather than a horror movie! Nevertheless some researchers from the University of Nottingham used the amount of sweat from hands to measure volunteer’s response to horror movie suspense to determine which type of suspense makes the best horror movie. Of four types of suspense; direct (as if we are the first person), shared (we empathise with a character’s situation), vicarious (when we’re aware of the danger but the character isn’t) and composite (all of the above), the most intense type of suspense was vicarious. So in that case, bring on the shower scene of Hitchcock’s Psycho (1960)!

It is the rush of the hormones adrenaline and cortisol that prepare our bodies for either fight or flight enabling us to take action in the face of danger. Adrenaline was the first hormone isolated in the 20th century by the Japanese chemist Jokichi Takamine (1854-1922) and it has different effects depending on the cell it is working on. Our heart rate and blood pressure increase, our pupils dilate, the body’s metabolism is changed to maximise blood glucose levels and blood is distributed to the muscles. Cortisol acts similarly on the body’s metabolism. The effects of adrenaline are so powerful on us in moments of great stress that it can make someone “superhuman.” Our senses are heightened and the effect upon muscles means we can undertake feats that usually we cannot do, such as lifting a 1360 kg car! But too much of these hormones can lead to stress. There is a base level release of cortisol throughout the day, but when too much of it is released over a prolonged period it leads to chronic stress. Perhaps some yoga or meditation is in order?


But all of this happens so fast that you don’t even register it. Before you know it, you have either jumped out of the way of the speeding car or most likely at this time of year you’ve squeezed your partner’s hand a bit too much. There aren’t many horror flicks that do scare me, but The Woman in Black (2012) significantly affected me! So if you like me have few dopamine receptors, here are some horror films that will get your scare on: The Invitation (2015), The Witch (to be released March 2016).
Happy Halloween folks!

Danae Dodge

I received my PhD in Scientific Archaeology from the University of Sheffield in 2011 which specialised in ancient DNA and anthropology. For my profile, see my websites: I started getting involved in Science Brainwaves as a volunteer in 2010. I have volunteered at presentations, events (such as the British Science Festival in 2011) and even participated in the Science is Vital protest march in October 2010. My first blog for Science Brainwaves was "Ancient Humans: Who were they? And who got it on?" which was the written version of a talk I gave for the Natural History Society at the University of Sheffield on 5 December 2011. I also have a public engagement page dedicated to ancient DNA, which I encourage both the public and specialists to join: