The Alaska Factor — The Science Writer

Optical deceit in vast landscapes

by Mark Jordan
June 10, 2022

In every respect, Alaska is a superlative landscape.

One does not merely view the countryside; one encounters it, succumbing to its nepenthean forces. The native Aleut language named this vast, hypnotic countryside “Alyeska,” meaning “the great land.” Today, it also bears the nickname “the Last Frontier.” Each moniker's etymology captures a revered human relationship with this imposing terrain.

With powerful earthen jaws, Alaska gnashes all your senses.

It deceives just one.

During a quarter century of exploration as a pilot and expedition guide, I have learned that the size and scope of Alaskan terrain are cunningly deceptive. Seemingly tiny rocks are monstrous, house-sized mega-boulders. Glacial crevasses, mere cuddled slivers viewed at altitude, are large enough to swallow a bus. On Denali National Park scenic flights, passengers routinely say, “Please turn before you hit the mountain,” when the mountain is still many miles away. Students on mountaineering trips continually misjudge the breadth and scale of navigable terrain.

How can our visual perceptions be so inaccurate? What is going on here? Alaska's elysian topography, a trickster landscape scaled beyond human belief and comprehension, presents an optical illusion. Locals call this phenomenon “the Alaska factor.”

To understand what causes optical deceit in immense landscapes, I contacted Stephen Macknik, director of the Translational Neuroscience Laboratory at the State University of New York Downstate in Brooklyn. His mission is to study the neural underpinnings of visual and sensory awareness and perception.

Macknik described his youth living on a Maui volcano, where his father was an astrophysicist. He recalled the challenges of estimating depth, distance, and size of terrain features while hiking around the Hawaiian observatory atop the 10,023-foot summit of the Haleakala volcano. He has a clearer understanding of the neural processes causing these illusions in his current research role.

The Müller-Lyer illusion, published by Franz Carl Müller-Lyer in 1889. Image credit: Fibonacci, CC BY-SA 3.0, via Wikimedia Commons.

Macknik said that humans use two sensory systems to establish cues for distance: central and peripheral vision. Each helps to establish congruity between reality and our perception of it.

Visual processing works subconsciously, and two symbiotic systems shape how a person interprets — and misinterprets — visual stimuli. Central vision is involved in identifying objects close to the center of the visual field, where acuity is best. Peripheral vision interprets inputs on the edges of the visual field. It excels at both motion detection and the perception of flicker stimuli. Each symbiotic part gathers distance cues, affecting how a person sees the stimuli reaching the brain.

Macknik emphasized a third factor, a trait predominant in natural settings called a “fractal,” a geometric figure or curve “such that any small part of it, enlarged, has the same statistical character as the original.”

“Mountains are fractals,” added Macknik. “They look pretty much the same no matter what your distance is from them.” The unique characteristics of fractal objects combined with visual perception, which is often duped by erroneous distance cues, are vital to understanding landscape illusions.

Fractal objects are everywhere — seashells, snowflakes, mountain ranges, coastlines, lightning, clouds, trees, broccoli, and Jackson Pollock paintings. Endemic to many natural environments, they are ubiquitous in surroundings dissimilar to the temperate forests and savannas where humankind's neurology evolved. Understandably, fractals are antithetical to modern urban scaled topographies that are self-designed for our cognitive traits.

Euclid, from Alexandria, Egypt, around the turn of the third century B.C. established the mathematical principles of non-fractal geometric forms. Chairs, cars, buildings, and an inviting cup of coffee on a nearby table are all examples of non-fractal objects. Euclidean geometry assigns values to an object’s length, height, and width, yielding attributes like area, volume, and circumference. Euclid’s theorems codify a neurological process the brain has evolved through millennia: establishing the size and distance of objects and determining spatial relationships between objects.

This image by psychologist Akiyoshi Kitaoka demonstrates how easily our visual processing system can misinterpret visual stimuli. The image is an optical illusion — although it is static, it appears to move. Image credit: Akiyoshi Kitaoka.

Fractals, however, exhibit two disorienting properties: self-similarity and scale independence. Self-similarity is when an object's parts mimic its whole. Scale independence is when an object has identical elements regardless of the viewing distance, and it becomes impossible to discern its scale.

The most extreme examples of fractal terrain are in the Arctic and the Antarctic — immense, homogeneous landscapes lacking contextual clues for distance. Like Alaska, these regions present a challenge to human visual processing.

“Our visual sensory system rigorously parses information into patterns, shapes, lines, and contrast,” writes William Fox in his 2005 book, Terra Antarctica: Looking into the Emptiest Continent. The eyes are conduits to the optic nerve, which transmits information to the brain's visual center for interpretive processing. Eventually, all discrete signals encoding information about an object's distance, speed, brightness, and color coalesce in the neocortex, defining the physical space a brain seeks to navigate.

Pattern information is vital for humans to establish equilibrium and understand the environment they inhabit. In aviation, loss of visual clues is a serious event that can severely debilitate a person.

The U.S. Federal Aviation Administration identifies flat light and whiteout as “optical illusions causing an individual to lose their depth of field and contrast, obscuring features of the terrain, and creating an inability to distinguish distances.” In a complete whiteout, “there are no shadows, no horizon or clouds, and all orientation is lost.”

A pilot untrained in instrument flight skills who plunders into nonvisual conditions can succumb to “the leans,” leading to a “controlled flight into terrain” accident. This refers to the final disorienting moments a pilot experiences while flying a mechanically sound aircraft into the ground or sea.

In a much different scenario in Terra Antarctica, Fox recounts how World War II long-range bomber pilots were diagnosed with a chronic condition brought about by endless hours looking through their aircraft windscreens at a featureless horizon. Their eyes suffered a short-term inability to focus.

These are examples of what can happen in environments where visual cues are few to nil, or when meteorological conditions reduce or deprive visual stimuli. Alaska, Antarctica, and similar panoramas are places of raging and exquisite beauty, but their massive fractal landscapes proffer deceptive scale and distance signals to our senses.

Nineteenth-century scientists were the first to document misleading distance cues. Sociologist Franz Carl Müller-Lyer in 1889 published an optical illusion consisting of three stylized arrows: one with fins protruding inward, another with fins protruding outward, and the third with one fin inward and one outward. Viewers task themselves to compare the arrow shaft lengths. Psychologists Hermann Ebbinghaus and Joseph Delboeuf published similar illusions.

Fractal terrain, like this one in Chile’s Northern Patagonian Icefield, distort the ability to process visual information. Image credit: Mark Jordan.

Each demonstrated that an object’s perceived size or distance varies in relation to the size of adjacent elements or the negative space they create. Proximal links and object spacing are essential cues for estimating depth, distance, and size. This is especially true when the brain knows (or thinks it knows) the size of some elements in a scene. Human vision has evolved to make estimates aided by comparisons with known objects. The Alaska factor offers few such crutches to help stabilize perception.

Distance cues come in two categories, binocular and monocular. Binocular cues, which are received by both eyes, include disparity and convergence, which help the brain interpret objects at far or close range. Disparity for far objects occurs when each eye sees a slightly different image because they are set apart. The brain must stitch these two stereo images into a single three-dimensional scene. Convergence occurs when looking at a close-up object: the eyes angle inwards, and the eye muscles signal the brain about an object's closeness.

Stereoscopic vision, a type of binocular vision, is the fusion of slightly angular differential views of a scene into a single three-dimensional image. It is a high-functioning system our species developed during evolutionary millennia. Now that we are exploring other planets in the solar system, we have borrowed the benefits of this ocular architecture for the most recent lander on Mars, NASA’s Perseverance.

Kathryn Powell, a planetary scientist at Arizona State University, is part of the project operations team contracted by NASA's Jet Propulsion Laboratory to run the Perseverance rover’s Mastcam-Z camera system. The moniker is a compound mashup derived from the words “mast,” “camera,” and “zoom.”

“We take a lot of our imaging in stereo utilizing Mastcam-Z's left eye and right eye,” said Powell. The camera's twin lenses, set approximately nine inches apart, can record 11 unique colors, take 3D and video images, and zoom from wide angle to telephoto — strong enough to view a housefly at the far end of a soccer field, according to NASA.

Before landscape painting became a distinct genre in Western European art, Renaissance painters used an understanding of monocular cues — information gleaned from a single eye — in portraiture. Objects that appear sharp, clear, and detailed, for example, are seen as closer than more hazy objects lacking luminescence. Superposition is one object's appearance in front of or behind another object, varying in range to an observer. Renaissance paintings effectively mimic what our retina and brain are tasked to accomplish, depicting a three-dimensional reality onto a two-dimensional surface. Leonardo da Vinci's Mona Lisa uses chiaroscuro, Italian for light (“chiara”), and shadow (“scouro”), to convey the depth of field and create visual focal points on a canvas. When an object filters through more or less air, atmospheric perspective further enhances depth information by varying texture and color saturation. The Mona Lisa (or any three-dimensional scene depicted on a flat surface) is an optical illusion forged by exploiting monocular cues that the neocortex uses to establish distance, depth, and size in a visual scene.

Evaluating depth, distance, and size requires distance cues and one additional device, a cerebral constructive method called “top-down” processing. In the early 1970s, psychologist Richard Gregory posited that all perception relies partially on experience and prior knowledge. The brain has learned the dimensions of a chair, so the mind can use this information when you see one far off. Additionally, comparisons with surrounding elements help aid object perception. A human figure next to the far-off chair resolves to be short or tall, for example, based on the brain's prior “chair” experience, combined with other relational cues.

However, these determinations are critical because all cues lose their effectiveness beyond short distances, and top-down processing starts to falter without familiar proximal objects for comparison. This is relevant for the Alaska factor.

“Beyond very short distances, visual perception is flat without depth, like a painted set on a stage,” said Macknik. Viewing a nearby tree with a human next to it is within the scope of our sensory toolbox. Viewing a distant forested ridgeline with no familiar objects in place for comparison can easily create Alaska-factor deceptions.

In Terra Antarctica, Fox describes “visual dissonance that leads to cognitive dissonance when the brain yearns for visible object information but struggles with a lack of salient clues.” Macknik agreed. He said there is a disconnect between objective reality and subjective perception of objects that occurs with all visual illusions. “There are three possible outcomes for our visual processing,” said Macknik. “We may see something that is not there, fail to see something that is there, or even see something different from what is there.” Visual perception is a marvel of evolutionary engineering, but many optical tricks can fool our senses and distort our neural re-creation of physical reality.

Alaska and all backcountry landscapes — mountain-scapes, desert-scapes, ocean-scapes, forest-scapes, rolling hill-scapes — are fractal tricksters. Biology has bestowed on humans extraordinary visual processing. Our dominant sense is estimated to absorb nearly 80% of the information needed to discern our environment. Still, millennia of evolution have not perfected our visual perception system and our ability to discern nature's reality fully.

Standing on the Kahiltna Glacier, one can stare in awe at Mount Hunter’s massive northwest wall and gaze slack-jawed at its vertical deception. This 14,573-foot behemoth of alpine rock, snow, and ice juts sublimely towards the cerulean sky. Sunlight brightens its ramparts, enhancing the paradox of its scale. In February 2010, Masatoshi Kuriaki, a prolific Alaskan Range mountaineer, attempted a winter ascent of Mount Hunter’s remote, frigid summit. His climb brought him only to 10,830 feet on the ridge, still more than 3,700 feet shy of the summit. His entire expedition lasted 83 days, including 53 days in snow caves protected from poor weather. He eventually retreated, never attaining Hunter's citadel crown. Kuriaki's adventure embodies a gargantuan and quixotic effort against an enigmatic topography. While most sojourns are not as extreme, we are all, like Kuriaki, intrepid explorers seduced by wilderness — willingly lured by the grandeur and duplicity of natural landscapes.

Mark Jordan

Mark Jordan has 25 plus years of experience working in international outdoor education. Additionally, he has worked as a commercial pilot and has a seven-year global healthcare consulting tenure.