Fantasy Science Pt. 26: Invisibility In Fiction & Human Vision
Time travel. Black holes. Invisibility. Have you heard terms like these flying around the science fiction sections of the film/TV world? Have you ever wondered just how accurately these films portray real science? Well, my friends, this column is for you! Fantasy Science & Coffee, aims to bridge the gap between science and science fiction in films and popular culture. My hope is to explain things in a fun way – like we’re chatting over coffee.
You may be thinking: who is this person, why does she think she can explain science, and why the heck would I want to have coffee with her? Well, I’m Radha, a physicist in India. I quite like hot beverages. I’ll also pay.
In this twenty sixth part of the series published on the second Tuesday of every month, back after a short hiatus, we are going to chat about invisibility, and how I think it may be plausibly explained in fiction because of how vision works. Our chat today focuses on vision and perception, not technology that may mimic invisibility.
Invisibility in Harry Potter, Doctor Who, and The Wheel of Time
Imagine you’re a character in a famous fantasy story. There’s a big, bad nose-less villain you need to pass unnoticed. You could perhaps create a distraction. But the cooler way would be to use that awesome Christmas gift from an eccentric Headmaster of a magical school. Because who wouldn’t want to use Harry Potter’s Cloak of Invisibility?
Invisibility, in varying degrees and forms, is a common plot device in the worlds of science fiction and fantasy. Some stories make use of complete invisibility, such as that provided by the famous invisibility cloak in the Harry Potter book and film series. The cloak is one of the fabled deathly hallows, and is said to have been created by Death himself. It renders the wearer completely invisible.
On the contrary, the purpose of the Warder cloak in “The Wheel of Time” book series by Robert Jordan (soon to be tv series, yay!) is not invisibility, but camouflage. Warders, protectors of women with certain supernatural powers called Aes Sedai, wear color-shifting cloaks that don’t render them invisible, but rather allow them to blend in with their surroundings. Here is the first description of Lan, the Warder to an Aes Sedai named Moiraine from “The Eye of the World“:
As [Moiraine] left, a tall man Rand had not noticed before moved away from the front of the inn and followed her, one hand resting on the long hilt of a sword. His clothes were a dark grayish green that would have faded into leaf or shadow, and his cloak swirled through shades of gray and green and brown as it shifted in the wind. It almost seemed to disappear at times, that cloak, fading into whatever lay beyond it.
Some stories make use of ‘visible’ invisibility, like that provided by the chameleon circuit in Doctor Who. The iconic Tardis symbol, the blue police box, is actually a mistake; a functioning chameleon circuit would let the Tardis assume any shape to fit in with its surroundings. From the miniseries Meanwhile in the Tardis:
The Doctor: It’s camouflage. It’s disguised as a police telephone box from 1963. Every time the TARDIS materializes in a new location, within the first nanosecond of landing, it analyzes its surroundings, calculates a twelve-dimensional data map of everything within a thousand mile radius, and determines which outer shell would blend in best with the environment… And then it disguises itself as a police telephone box from 1963.
Amy Pond: Oh, why?
The Doctor: It’s probably a bit of a fault, actually. I’ve been meaning to check.
Is there a plausible explanation for fictional invisibility? Let’s pretend that we have color-shifting fabric and the ability to fabricate chameleon circuits. I imagine that they’d function by targeting our brains’ processing of visual inputs. You see, our eyes are just collectors of information. Vision lies mostly in our brains, and not our eyes. It’s up to the brain to interpret our visual inputs.
Vision is in the Brain
Take a look around you. Observe the details of your environment. Maybe there is a blue mug half filled with neglected cold tea sitting on a desk. Or an oddly shaped stain on the ceiling. Or perhaps there’s a person in a red shirt chewing gum sitting close by. That the world appears to be seamless, three-dimensional, richly detailed, and stable isn’t the work of your eyes, it is the work of your brain. Very complicated work. It’s the brain that decides what to do with all of the raw data falling onto your retinas, choosing what to ignore, and what it should pay attention to. The retina has high resolution only over a few degrees of visual angle.
Our eyes aren’t actually ‘on’ all the time. They undergo rapid voluntary movements called saccades, that enable us to quickly change our focus and collect visual information. These movements occur about three times in a second! Yet our perception of the world is stable and not blurry thanks to saccadic suppression: we don’t register visual inputs during these rapid movements. Our brain fills in the gaps, making our environment appear seamless and stable.
Depending on what task we are performing, our brain decides what to focus on. This visual attention helps us piece together features such as color and shape of complete objects.
Strictly in the context of science fiction, I imagine manipulating this visual attention could plausibly lead to some degree of invisibility. Perhaps the chameleon circuit radiates something that tells brains that the Tardis isn’t significant enough to focus on or register. Or…perhaps it is simply a flaw of the human race to see only what we want to see. As the Ninth Doctor said in the eleventh episode of Series 1:
Ricky, let me tell you something about the human race. You put a mysterious blue box slap bang in the middle of town, what do they do? Walk past it.
I digress.
A Warder cloak in “The Wheel of Time” wouldn’t use chameleon technology, but could instead be made of ‘slippery’ fabric that tricks brains into registering what is around a Warder more than anything significant about the Warder himself. And perhaps a Potter-esque cloak that renders the wearer completely invisible would make use of some tricky textile technology that makes our brains fill in the gap of what lies behind the wearer. Note that scientists are playing with light manipulation that may provide this effect, but today we are focusing on vision and perception, not technology that may mimic invisibility.
Persistence of Vision
I couldn’t, of course, write an article on vision in a film magazine without mentioning persistence of vision. It’s a term many cinephiles are familiar with, because it is why we see moving pictures when there’s a rapid succession of still images — it illustrates the ability of our brains to fill in the blanks. Essentially, persistence of vision means that our brains average what we see over short periods of time.
One of the most famous illustrations goes all the way back to 1878 when photographer Eadward Muybridge set out to answer the question: does a horse become fully airborne when it gallops?
From Time’s The Most Influential Images of All Time:
As a horse sped by, it tripped wires connected to the cameras, which took 12 photos in rapid succession. Muybridge developed the images on site and, in the frames, revealed that a horse is completely aloft with its hooves tucked underneath it for a brief moment during a stride. The revelation, imperceptible to the naked eye but apparent through photography, marked a new purpose for the medium. It could capture truth through technology.
This beautiful early form of stop motion animation and other similar experiments led to the birth of our beloved motion picture industry just a short while later. It’s a remarkable illustration of just how our brains have the ability to fill in holes and piece together visual inputs. And if I wanted to sneak past a big, bad nose-less villain in a fantasy world, it’s precisely this ability that I’d exploit to turn myself invisible.
More to Explore
Articles
Science Nordic: The eyes look, but the brain sees (2018)
The Mirror: Harry Potter invisibility cloak is one step closer to becoming a reality thanks to scientists (2018)
The Conversation: How do our brains reconstruct the visual world? (2015)
Science Alert: The Science Behind Optical Illusions (2015)
Scientific American: When Blindness Is in the Mind, Not the Eyes (2008)
Discover: The Vision Thing: Mainly in the Brain (1993)
Papers/Books
D. Purves, G. J. Augustine, and D. Fitzpatrick, et al., “Types of Eye Movements and Their Functions.” Neuroscience. 2nd edition. (2001)
R. A. Rensink. “The Dynamic Representation of Scenes.” Visual Cognition. (2000)
R. A. Kiltie, and A. F. Laineb. “Visual textures, machine vision and animal camouflage.” Trends in Ecology & Evolution. (1992)
Videos
Video by SmarterEveryDay on optical illusions demonstrating how persistence of vision works: “You won’t believe your eyes!”
Resources
Time’s The Most Influential Images of All Time
How Stuff Works: How Vision Works
Brain HQ: How Vision Works
Does content like this matter to you?
Become a Member and support film journalism. Unlock access to all of Film Inquiry`s great articles. Join a community of like-minded readers who are passionate about cinema - get access to our private members Network, give back to independent filmmakers, and more.
