The most terrifying part of Ghost in the Shell isn’t the vengeance of outdated robots but the unsettling presence of the robo-geishas. Wearing impassive white masks with dead eyes, they glide across white tiled floors and, when provoked, scuttle like spiders. In a previous interview with Inverse, the film’s costume designers broke down how they achieved the geishas’ eerie looks, but understanding why those looks are so discomforting requires more probing. What do our brains actually perceive when we see them?

Let’s start first with what we see in the film. In the interview, the film’s costumers Kurt Swanson and Bart Mueller, who go by Kurt and Bart, explained that the mask and traditional makeup were key to the geishas’ creepiness. Mueller said:

The geisha are very eerie, and I think a lot of that is because of their machinate porcelain masks which were an amplification of traditional geisha makeup which is a mask in its own way. To have the painted face and soulless eyes blinking is really unsettling. We wanted the design to be an imagined evolution of very specific cultural tradition that has a sense of privacy that borders on secrecy.

Masks, like the geisha’s thick layer of makeup or even that of a clown, allow a human face to toe the line between reality and fantasy, and our brains find this too disorienting to be pleasant. Sure, the ghost-white face of the robo-geisha has eyes, a nose, and a mouth just like a normal human face, but here it’s distorted — the face is too colorless, the red stripe on the lip thwarts our conception of a normal lip shape, and the eyes are hollow where the pupils should be.

Taken together, this jumble of features confuses the brain, which is wired to assess whether a thing is threatening or not. The robo-geishas, like clowns and the crazy viral hit “Hi Stranger”, are too ambiguously human for us to tell.

Robo-geishas: ambiguously threatening.

As researchers explained in New Ideas in Psychology in 2016, this ambiguity is what triggers the feeling of being creeped out. The brain can’t tell whether it’s supposed to feel hostile toward the geisha, but it also isn’t sure whether the geisha is benign, so it prepares itself in a sort of intermediate state of wariness. Feeling creeped out, they explained, “is an evolved adaptive emotional response to ambiguity about the presence of threat that enables us to maintain vigilance during times of uncertainty.”

But maybe not so ambiguously threatening after all.

Ambiguous though the geisha’s overall look may be, another explanation for why they make us feel so unsettled may be lurking in their empty eyes: In 2004, an article published in Science reported that the brain’s amygdala — the part responsible for maintaining vigilance — becomes more active when it sees wide, surprised eyes. The amygdala had long been known to become activated when it sees scared-looking faces, and the study shows that the trigger is seeing larger sclera — the whites of eyes — rather than smaller ones. Lacking pupils (and therefore being all sclera), the geishas’ empty eye sockets may also lead to the sense of heightened vigilance we interpret as creepiness.

Of course, as anyone who’s seen Ghost in the Shell knows, there’s no reason to be confused about the robo-geishas — they definitely are threatening, so the unsettled feelings and heightened vigilance you feel when seeing them are absolutely warranted.

Photos via Ghost In The Shell