Humans can tell when someone is watching them.
“I feel like someone is watching me” is a classic horror film trope, but the idea also taps into a biological fact: Humans are good at sensing when someone is looking at them. While some label this gut feeling a kind of sixth sense, it’s really a biological phenomenon known as gaze detection, caused by a complex neural network in our brain. This detection system rests largely in our peripheral vision; the sense dissipates quickly when someone turns only a few degrees away from us. Because some 10 regions of the brain are involved with human vision, and little is known about gaze detection generally, scientists haven’t pinpointed what’s controlling this seemingly uncanny ability — although researchers have detected a dedicated group of gaze-detecting neurons in macaque monkeys.
Gaze detection is particularly interesting in humans because our eyes are unlike any other in the animal kingdom. The area around the pupil, known as the sclera, is very prominent and white, which makes it easier to discern in what direction someone is looking. The overall theory as to why humans are so good at gaze detection boils down to the evolutionary advantage of cooperation. Simply put, humans are social creatures, and the detection of subtle eye movements helps us work with others while also helping us avoid potential threats. But because of the evolutionary importance of knowing when someone is looking at you, our brains tend to oversignal that someone is staring at us, when they’re really not. So if you’re ever feeling a bit paranoid, blame your brain.
We’re all familiar with the supposed five senses — smell, taste, touch, sight, and hearing — but humans have far more senses than that. One of them is called proprioception, a sense that helps our brain interpret where we are in space. This sense is derived from small receptors (called “piezo2” receptors) located in our skeletal muscles and tendons, which act as a kind of gateway through which mechanical motion enters the nervous system and gives our brains a sense of spatial awareness. Proprioception is what allows you to meander through a pitch-dark room and still have a sense of yourself occupying a particular space; if asked, you could touch your nose, hop on one foot, or do other tasks even though you can’t see. This sense isn’t as easily understandable as the basic five, but it’s a big deal if you’re missing these crucial receptors. In 2019, Vox spoke with someone missing this sixth sense, and she said that when the lights go out, it’s as if “you had a blindfold and somebody turned you several times, and then you’re asked to go in a direction.” So while the human body does an incredible job mapping the world with its five senses, there’s a lot more going on than you may realize.
