[INTRO ♪].

Ever feel someone watching you? Like, you just know they're staring, even if you're not looking at them?

It's not some psychic sense, as cool as that would be. Psychology researchers call it gaze detection—your ability to recognize where a person or animal is looking. And even though we don't have all the answers about how it works in humans, science has provided some pretty good evidence as to what's going on in your brain.

Various studies suggest that gaze is processed preferentially by the brain, meaning it's processed faster and more accurately than some other kinds of stimuli. Especially when it's on you, which is called direct gaze. Your brain has a pretty big network of areas that handle different aspects of getting information from faces.

Like, there are regions that respond to shape, orientation, or specific features. That sort of thing. And when it comes to gaze detection, scientists believe an area in this network called the Superior Temporal Sulcus, or STS, is responsible for telling you exactly where someone else is looking.

Studies looking at a comparable area in the temporal lobe of macaque monkeys found cells that are tuned to the orientation of both the head and gaze direction. For instance, one study from 1985 had macaque monkeys look at faces of other macaques. And they found that 63% of the 182 cells that were probed fired in response to changes in head direction.

More than half of that 63% also responded to changes in gaze direction, and a few responded to direct gaze. Researchers assume the Superior Temporal Sulcus works similarly in humans, since performing the same sort of experiments in living humans is too invasive. Now, it's easy enough for your brain to figure out where a gaze is pointed when you're looking right at someone.

But what about that feeling of being watched when you can't see someone's eyes clearly? In your peripheral vision, the resolution becomes low enough that details are harder to see—like, where someone's pupils are with respect to the whites of their eyes. In this situation, your brain starts to take head orientation as evidence of direct gaze instead.

Researchers studying this in 2015 tested how well participants could identify the gaze direction of faces with different orientations presented at different eccentricities. They had participants stare straight ahead, so a face straight ahead would be 0 degrees eccentricity, and in line with their shoulders would be plus and minus 90 degrees eccentricity. And they generally found people could accurately tell where a gaze was directed up to 6 degrees eccentricity.

Which isn't that much before we kind of start to suck at it. Overall, gaze discrimination got less accurate farther away from zero degrees. Which makes sense, because farther from zero degrees means more blurry peripheral vision.

As details of eyes became less clear, participants relied more on head orientation to figure gaze out. This swayed their answers, and wasn't always accurate. This and the results of a similar study from 2015 showed that if faces in the periphery were pointed right at participants, they were more likely to assume it was a direct gaze.

So, basically, if someone just out of your line of sight is facing you, your brain assumes they're looking right at you. If their head is turned, you're more likely to assume they're not looking at you, no matter where they're actually looking. And as for the spooky feeling of “that person behind me is looking at me, I can feel it” thing, there is an explanation for that too.

Even though nobody actually has eyes in the backs of their heads. Turns out, we might just tend to assume people are looking at us. All the time.

In research from 2013, scientists showed participants a series of faces and eyes under different levels of noise filter that basically made them look blurry. Some were really clear, which made it easier to read the gaze. And others were pretty obstructed, so they were less easy to guess at.

The researchers asked participants to judge whether or not the faces were looking at them. And they found that in trials where the faces and eyes were obstructed by noise, participants were more likely to perceive the gaze as directed at them. In real life, the scientists took this to mean that in situations where you can't know where people are looking—like when it's dark, someone's behind you, or they're wearing sunglasses—your brain is automatically making you feel watched.

And I mean, come on brain! We're interesting, but not enough to be watched all day, every day, by everyone whose eyes we can't see. It might sound like sort of a silly assumption if I put it that way.

But evolutionarily speaking, knowing when someone or something is looking at you could be really important. They might be planning to attack, so it's best to be on guard. Besides that, knowing if you're being watched also lets you interact socially.

If someone wants your attention, whether it's your friend or your baby, it's way easier to notice if you're already unconsciously scanning for people looking at you. So sorry, you're not psychic. You just have a solid and comprehensive and well-designed gaze detection system.

And that's just as cool, right? Thanks for learning with us here on SciShow Psych, and thanks especially to our patrons on Patreon whose support makes all these videos possible. If you want to join our community, you can go to patreon.com/scishow.

Or share this video with your friend who swears that he has a spidey sense for being watched. [OUTRO ♪].