Watched a scary movie last night and reminded me of that feeling when you sense someone or something approaching you from behind.
In: Biology
Things I know of include heat, light, and air movement. We can sense the heat of other people, and especially if it is unexpected we find it very unnerving. When there is movement behind us, it often causes movement in light patterns in front of us – anything from clearly cast shadows to subtle changes in brightness can cue us in. Lastly, the movement of air can give us the impression of something solid being near us.
We survived by evolving mechanisms that kept us alive. Being able to see, hear, smell etc a danger allowed those who did the abovementioned seeing/hearing/smelling better to survive. So in the background of our normal lives our brains compile a bunch of data (sounds we hear, weird changes in wind, etc) to create potential possibilities. Your “top-level” consciosness doesn’t need to know that air shifted slightly, every time that happens. But if the air shifted slightly, and there was a small noise, and a few other things, then your “survival” part of brain makes the incredibly complex math of “Sound + movement = someone else, ALERT” and gives you the feeling of “i should turn around and check”.
This is especially increased when you are stressed or fearful – i.e. watching a scary movie. Your body is preparing itself for fight-or-flight, and thus pays even closer attention than usual to minor details.
tl;dr – you get that feeling because millions of years ago monkeys that got that feeling survived to make babies more often than the monkeys that didn’t get that feeling.
You see a shadow, hear a faint noise, a whiff of odor, feel body heat or the stirring of the air. Often the alarm of someone appearing unexpectedly behind will make you forget exactly what sensation alerted you.
Confirmation bias plays a role as well. You remember all the times when you sensed someone they were there, and forget when it was a false alarm.
So first things: There are more than 5 senses, that was something the Greek philosopher Aristotle proposed and its just never gone away.
So your sense aren’t wired directly into your consciousness, they pass through another part of your brain that is very simple, all it does is look for alerts and kicks a signal to the higher level of your mind. This enables us to sense and react to danger really fast. This process is fast than letting the information just reach your consciousness and allowing your executive functions (part of the brain for making decisions) to assess and decide on how to act.
This early-warning system looks for different information compared to your high-level mind, this helps it remain relatively simple (not having to sort sounds from spoken words to match to meanings of those words in memory etc) and also prevents your brain from being wasteful with double processing.
Now our senses are stronger than we realize, not quite the superhero daredevil, but we are more aware of our surroundings than we realize. Your higher consciousness will disregard a lot of incoming information so only “necessary” information gets consciously processed. Its basically filtering unnecessary spam. However this discarded information has already been checked by early-warning center. Take airflow for example, winds are something you feel because its significant enough due to the force. A cold breeze is registered by consciousness because its reducing your body temperature and you need to take a conscious action, eg put on a jacket, to stop it from going below your body’s preferred range.
When you’re in a high stressed state, your early-warning system is going to turn up lots of false-positives to your consciousness, this is part of the fight-or-flight response. This has a negative effect on your psychological health because you’re treating everything as a threat first before your conscious mind declares each false-positive to be harmless.
Now here’s how you can feel the presence of others. Something like airflow, sounds, scent, visual markings etc, are all carrying signals that the early warning system is looking for and feeding up to your higher consciousness. This mechanism is simple so it can’t say “the disturbed ground shows someone was here. That smell is another human’s sweat. Those sounds are from fabric brushing against itself” It just sends a simple “ALERT” for every single stimuli. Your conscious brain has picked up enough to start actively looking at your surroundings and thus lowers the spam filter to get more of an idea on what the threat is.
If you work in a field where observation of subtle signals is critical (detective, forensic, search party tracker), your “gut instinct” is simply your conscious mind being trained enough to filter out less incoming environmental information.
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