Into the Illusive World: An Exploration of Animals’ Perception

By Paul A. Moore

Have you ever thought about what a dog smells as it stops to sniff at a tree? Or what a cat is watching as it stares intensely off into space? What about animals in the wild? What do they see, hear, smell, and feel? How do they perceive their surroundings? This is the illusive world. A world filled with fascinating stimuli that we are not equipped to detect. This is particularly true because we tend to rely so heavily on our eyes or ears.

We are figuratively, and literally, blind to this part of the natural world. This part, which is full of stimuli we cannot perceive, encompasses the daily lives of so many animals. Beneath our feet are ants, moles, and spiders using vibrations to coordinate colonies and communicate danger. In the oceans, turtles, fish, and octopi are sensitive to magnetic and electric fields, as well as tasty morsels at the tips of their tentacles. In the skies, owls and raptors can see deep into a lake or pierce the night with highly sensitive eyes. This book brings together all these animals and their amazing sensory abilities in an exploration of how animals perceive their world.

Within these pages are wonderful and exciting stories of organisms using their senses to perform sophisticated communication with nestmates, find hidden prey in the dark of night or murky of depths, and call to lovers both near and far. This book will open the door to this illusive world and will take you on a journey into the illusive world and see how different the world is when perceived through another animal’s senses.

• Language: English
• Publisher: Springer
• Release date: Jul 12, 2019
• ISBN: 9783030202026

Book preview

Part I

The Sensuous World

The truth is that from birth on we are, to one extent or another, a fairly sensual species.

—Jock Sturges

© Springer Nature Switzerland AG 2019

Paul A. MooreInto the Illusive Worldhttps://doi.org/10.1007/978-3-030-20202-6_1

1. What’s Mine Is Mine and What’s Yours Is Yours

Paul A. Moore¹ 

(1)

Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, USA

I step out of the van and straight into a real-world approximation of J.R.R. Tolkien’s Lothlórien, which was the famous Elven forest lying in a woodland valley. I am surrounded by large red and white pine trees. Although the pines are clearly dominating the landscapes, there are occasional low-lying cedar trees interspersed with tall ferns and mosses. The dark greens of the needles are contrasted with the reddish hues of the trunks and the oranges of last year’s fallen needles. Shafts of sunlight penetrate the gaps in branches and provide some light to the forest floor. I pause to inhale deeply. The splendor of nature greets my nose, and I am enveloped with a mix of earthen and pine aromas. The damp forest floors emit a heavy and peaty smell that connects me with the earth. The clean air and pine smells create a perception of pure nature. Finally, I listen. Just beyond my vision is a river. I can make out the familiar but distinctive and pleasing sounds of water rushing over rapids and small waterfalls. The sound is subtle, but because I have been here multiple times, I know the sound.

As I walk deeper into this mystical habitat and follow the sound of water, the world around me slowly changes. The abundant pine forest is slowly replaced by cedars and mosses. The ground becomes soggy as I approach the riverbank, and the dull greens of the pine trees are replaced with the brilliant greens of moss and fern. The aromas slowly transition from the earthen smells into an interesting set of odors arising from the river. The smells are hard to describe, but I recognize them as coming from a clear and clean river. The babble of a river has transitioned into a low roar of tumbling water.

At the river’s edge, I pause a second time. This river is a braided river. I observe the way that the water winds its way around, over, through, and under small islands. The islands are composed of fallen cedars ground over by moss, cranberry, and grasses. As I survey the stream, I see some 20 different small islands inviting biological exploration. With an immense sense of joy, I step from the bank and begin my trek out to the many islands.

As soon as my foot plunges into the knee-deep water, I am hit with intense shock and subtle pain. The river is icy cold (close to 12 °C according to my subsequent measurements with sampling equipment), and my leg begins to throb with the sudden drop in temperature. Having explored this river many times, I was expecting that sensation, but my expectations still don’t adequately prepare me for the shock. My other leg follows the first, and another shock to the system is registered. I remind myself of the advice I provide my students when sampling these rivers: Once your legs go numb from the cold, it isn’t so bad. With these words echoing in my mind, I press on with my mission to explore.

Midway to the first island, I stop to study the streambed. To the untrained eye, there appears to be nothing of significance here. A few pebbles, some gravel, lots of sand, and a smattering of plants are all that my eye captures. I reach in, grab one of the larger pebbles, and flip it over. With some closer inspection, I can see that this pebble is teaming with life. The first thing I notice is a small insect quickly moving across the bottom surface of the pebble. Despite its quick movement, I identify it as a stonefly. One of the larger aquatic insects, the underwater form of the stonefly, is actually a juvenile form called a nymph. Nymphs will live 1–3 years in the water before emerging as an adult. The stonefly is running in between small stone ovals as it tries to escape my field of view. The stone ovals contain another common aquatic insect called a caddisfly. These organisms are the master architects of the world and build their own homes out of wood, stone, and sand and even weave wonderful webs (technically nets) that would make spiders jealous.

These two insects may live their entire aquatic life on a few pebbles if the food is plentiful enough. Although these insects are at the larger end of the aquatic insect spectrum in regard to size, they are quite small compared to the fish, birds, and mammals that inhabit this beautiful stream. Yet, stoneflies and caddis flies are significantly larger than insects such as blackfly and chironomid larvae which, in turn, are much larger than algae and bacteria that live on the numerous pebbles in this part of the stream. The size range of life on this planet is immense if we consider everything from the smallest bacteria to the largest marine mammals. The size of an organism and its perspective of the world around it are so intimately tied together that this singular feature (size) shapes how we, and all of life, perceive the world around us.

For example, calling the bit of land that I am walking toward an island is probably a stretch of the word island. These small pieces of land vary in size from tens to hundreds of square meters, some of which are interconnected through fallen cedar trees. My fellow mammals, such as beavers and deer, can easily cross them in seconds. The aquatic insects and crayfish that inhabit these streams would take hours to cross them, and, still, other animals would perceive these islands as entire continents. Thus, the usefulness of the term island is entirely dependent upon the perspective applied. From my perspective, these parcels are barely larger than stepping stones. For the smaller insects, these islands are an entire world.

Perspective is actually determined by the perception of the organism in question. This wonderful habitat is full of sensory stimuli: some of which I am fully aware of and others pass me by unknowingly. The chill of the cold water on my legs, the smell of cleanliness in the air, the vivid green of the moss-covered rocks and trees, and the babbling sound of the water rushing over rapids are my world right now. These sensory experiences are my umwelt . This Germanic word means the world as it is perceived by an organism and was introduced into our vernacular by Jakob von Uexkull who studied animal physiology and behavior. von Uexkull needed a term to recognize that our perception of the world is different when compared to other animals. Given that animals have different sensory capabilities, their view of the world around them, and their behavioral repertoire, is guided by that perception.

In my little Tolkien world, my fellow organisms are actually inhabiting different worlds because they have different umwelts . Those larval insects on the bottom of the rock that I grabbed are what scientists call poikilotherms. This is the more apt term for what used to be defined as cold-blooded animals because some of these animals have higher body temperatures than homeotherms (warm-blooded animals). These organisms’ body temperatures are determined by the surrounding environment. Because the body temperature of these insects is identical to the surrounding water temperature, they are unaware of the cold that I feel. Their compound eyes provide them a different perspective of the riverbed, and their noses are tuned to different chemicals than my nose. Thus, all those sensations that I described above are missing from their umwelt and vice versa.

This beautiful habitat that I walked into only exists because of the unique combination of perceptual abilities that we have as humans. The beavers, deer, crayfish, hawks, trout, and even the various plants that inhabit this location each have their own umwelts which provides their own individual perspective on the surrounding environment. The purpose of this book is to provide you a glimpse into the various umwelts of the numerous animals inhabiting this planet. This field of scientific endeavor is called sensory ecology, and we have reached a point where we almost fully understand how organisms perceive and react to the sensory signals that are all around us. Thus, I want to share this understanding to you, the reader, such that you may understand what it is like to be an ant, a bat, a shark, or any other organism. My hope is that an appreciation of how organisms perceive this world might give us a fuller understanding of our interactions with nature, and, ultimately, we will become better stewards of this planet.

Before moving on, I should address a possible issue that might have given you pause in the previous paragraphs. I subtly used the word perspective when writing about how insects perceive the river in which they live. It is possible to disagree with the use of perspective in referring to animals and to argue that this word solely belongs in cognitive heady world of humans. I can hear the critics of this use responding that animals and certainly plants do not possess the cognitive ability to have a perspective. Perspectives require attitudes and complex thought processes in regard to past, current, and potentially future events. I would counter that our understanding of the ability of animals to think and understand complex concepts is still growing by leaps and bounds. We, as humans, have a tendency to want to be a unique species, and as such, we underplay or disregard the ability of organisms to do the same things as we do. Repeatedly, scientific investigations have systematically torn down concept after concept that separates us from other animals. Tool use? Other animals do it. Complex social societies? Nonhuman animals have it. Emotions? It’s there. The last bastion of specialness, language, is currently hotly debated as some scientists would claim that animals form and use language, while others would argue that the hallmarks of language (syntax and grammar rules) are absent. Given recent advances in both the experimental ideas of consciousness and more philosophical debates on the concept of consciousness, animals appear to have more mental and cognitive capabilities than what was thought years ago. Thus, I will continue to use perspective throughout this book as a mental capability of animals.

1.1 The Sensuous World

The joys of exploring. Whether I find myself in a new city or a stretch of nature, I feel some strange pull that tells me a good old walk is in order. An explore is what I call it. During these explorations, I unplug from the electronic world to immerse myself in the natural world. From these walks, I often discover interesting little secrets that provide a sense of wonder. Within urban environments, I am often on the lookout for a good hole in the wall restaurant. I choose ones that are often run by a family that really cares about food more than ambience and delivers authentic, lovingly cooked foods. Another urban find that catches my eye is the small bookstore, but sadly, these are going extinct. Traveling within natural habitats, I often search for the small and unseen. Moss, lichens, and flowers can be hidden among the taller plants but certainly create a distinctive appearance to the forest floor. On forest paths, small mushrooms on the underside of logs are often quite beautiful. I know of several hidden spots on well-traveled paths that have luminescent mushrooms that glow a wonderfully eerily blue or green in the dead of night.

Finding these mushrooms requires a strong belief in one’s abilities because the search for these rare treasures involves a midnight hike in the woods without a flashlight. Found in the underbrush or at the base of trees, these mushrooms are a great fall discovery. A hike in the woods at midnight with nothing but a crescent moon and glowing mushrooms to light the path is akin to an out-of-body sensory experience. As humans, we typically gather most of our information about the world from our visual and auditory systems. Nighttime walks in the middle of the woods are often devoid of these two main channels of information. Initially, there is a sense of disorientation until your body and mind adjusts to the situation at hand.

While I may be at a loss for typical sensory signals, there is a host of animals that have evolved to live within this habitat. I have often wondered about the role of these cues for the mushroom and what sort of creatures use these signals. One current thought is that nocturnal grazers are attracted to the light and come to the mushroom for a good meal. There appears to be no free meal though, because just like bees and flowers, these grazers will help the mushrooms spread and disperse around the forest. After grazing, the small mammals will transfer the spores of the mushroom that are caught within its coat of fur. Many nocturnal dwellers have adaptations like large eyes or a reflective tapetum that serves to amplify light. A large eye is similar to a large F stop on a camera which captures more light. The tapetum lucidum is a reflective structure that sits at the back of the eyes, behind the photoreceptors, of nocturnal vertebrates. Light rays that are not captured as they pass the photoreceptors a first time are reflected back across the receptors which give the receptors a second chance to absorb the light. Given that my own eyes have evolved to be used during daytime, my diurnal eyes struggle to see the otherworldly glow of the mushrooms. I wonder if these mushrooms, while dim for me, stand out as beacons to the nocturnal grazers with their far more sensitive eyes.

On one of my more recent hikes to find these mushrooms, I came across an opening in the trees where the faint moonlight shone through to the forest floor. This whisper of moonlight was enough to wash out the green light from the mushrooms, so I turned my gaze toward the skies. This path is located in an area of the country that is devoid of human lights, so the skies are often beautifully lit with the Milky Way, and certain features of the moon can be seen on particularly clear nights. On this night, as I strained to see any craters on the surface, I noticed some quickly moving dark flashes fly across the front of the moon. I recognized these shapes as another favorite nighttime animal of mine, the bat. It appears as if this night has brought out several bats as I could almost follow several different shapes as they zig, zag, and drop chasing insects in the clearing.

These creatures of the night, having limited visual signals present, use ultrasonic sounds to hunt down their prey. I can imagine that their world might be similar to my nighttime hunt for mushrooms. They, like me, are hunting for a small prey, whether mushrooms for me or insects for them, in a dark and silent world and sensing reflected stimuli. Their stimulus is the sound bouncing off flying insects, and mine is the light reflecting off trees and being produced by the mushrooms. Unlike my sensory world, these bats are creating their own umwelt by producing the calls that bounce off the prey and echo into their ears. These patterns of echoes carry information that is reconstructed by the bat’s brain to produce a three-dimensional world of objects. Some bats create such precise audio worlds that they can successfully navigate a room containing large amounts of randomly strung fine fishing lines. Many of us would be hard pressed to navigate this room in bright light with our eyes wide open.

As I watched the bats dive and weave catching their nightly nourishment, I wondered how my present location would appear to me if I could echolocate. As I scanned my darken surroundings, I caught faint glimpses of tree trunks, a couple of mushrooms on the forest floor, and some small foliage with leafy edges fading into the darkness. As I hiked out to this spot, I had to travel quite slowly so that I would not trip over the occasional tree root or larger rock. What would my umwelt be if I listened with my ears for echoes as opposed to watching with my eyes for reflected light? Could I hear the roots as potential tripping hazards and be able to travel must faster? Could I hear the particular shapes of the mushrooms that pop out from the base of trees?

Have you ever wondered what it would be like to be another person? Another animal? As a pet owner, I have stared at both of my cats and my dogs and often wondered what they were seeing, smelling, and ultimately thinking. I can say the word out or treat and see my dogs head cock to one side, ears perk up, and a narrow focus on his eyebrows. It is at this moment in time that I would love to hear and smell the world the way a dog does. What is it like to be a dog?

Could I walk a proverbial mile in their shoes, hooves, or paws? This is the question that the American philosopher Thomas Nagel wrestled with in his often quoted 1974 essay What is it like to be a bat?. This essay is an essential read for any beginning student in philosophy. Within the paper, Nagel argues against what is known as the materialistic theories of consciousness. Materialistic theories state that what we call the mind and consciousness naturally arises from the large number of neuronal connections within the human brain. The same holds true for other animals that have various levels of conscious states. In other words, who we are is nothing more than intricate and detailed wiring within our brain. Nagel argues that consciousness and everything that comes with that consciousness (love, sadness, good, and evil) is more than just the complex wiring of a highly advanced computer (our brain). There is an essential (but unnamed) factor that creates consciousness. To strip away everything that makes us human to merely neural connections misses the essential elements of what consciousness means. These essential elements make the mental state of other organisms unique and inaccessible to us. Thus, to Nagel, attempting to fly a mile in a bat’s mind is a fruitless endeavor. I would disagree with Nagel. Let’s try a task that is much closer to our own perceptual world before we jump into a bat’s brain.

Consider, for a second, the perceptual world of a red-green color-blind human. Simple tasks that the rest of us would perform one way are often modified by people with these color deficits. Most of us, while driving in any urban environment, would pay special attention to the colors of a stoplight. Red meaning stop, and green meaning go. Other sensory cues are most likely ignored or only play a minor role in our decision on which pedal to press within the car. One of those sensory cues is the location of the lights. Red is on top and green on the bottom. I would imagine that we could flip those locations and probably not cause too much problem for most people. Red-green color-blind people would be at a loss. For them, the colors of the stop and go signals are indistinguishable, and what carries the key piece of information for them is the location of the light. If the top light is on, that means stop. If the bottom light is bright, that means go. While the total sensory image is the same for both people, the color-blind individual perceives and responds to location of light, whereas the normal-sighted individuals respond to which color is lit. This translation in information appears to be an easy step to make. So, is it possible to imagine what the world is like for a red-green color-blind human? Seems like it may be possible.

Still, trying to imagine how the mind of a color-blind human works is a small step compared to nonhuman animals. In the small little forest section around me, bats, moths, gnats, owls, deer, moles, and mosquitos are just a few of the animals that keep me company on a dark night. Each of them had different sets of perceptual abilities guiding their movements and behaviors. Beside the sensory capabilities of the bats previously mentioned, the mosquitos, who craved a meal to be siphoned from my arm, searched for little puffs of CO2 that are being exhaled from my nostrils. The moles, who built tunnels underneath my feet, used exquisitely tuned vibration detectors on their jaws and feet. I wondered what they sense every time I take a step and send waves of energy through the ground. Called seismic detection, some snakes have receptors in the jaws for sensing animals moving along the ground. A couple of these nighttime denizens were homing in on the heat signatures coming off warm bodies such as my own.

This nighttime world, as well as any other habitat, is full of sensory signals that are undetectable to us because we either lack the sensory equipment or the sensitivity to detect those signals. Each animal has its own unique sensory world tuned through evolutionary processes to those range of stimuli that carry important information for them. The sensory signals and the information carried within those signals give rise to the perception and perspectives that is their world. This combination of signals and stimuli is the sensuous world alluded to in the title of this section. A world beyond our ability to comprehend and, because of that failing, potentially inhibiting our ability to understand how other animals interact with the world around them. Our ignorance or woeful neglect of these other sensory perspectives can lead to serious ecological problems. The lights of beach houses cause baby sea turtles to navigate toward beach house lighting, away from the ocean, which is a lethal choice. In high traffic and urban areas, the increase in background noise drowns out alarm calls and, as a result, has caused significant alterations in bird songs. The large number of anthropogenic chemicals that are being infused into the world’s freshwaters is disrupting mating systems in many fish. These are just a few instances of how humans have negatively altered the sensory landscape of other animals.

1.2 The Mind’s Eye

Even within our own sensuous world, the importance of our own senses in coloring how we perceive the world is often underappreciated. Our eyes, ears, and nose as representations of our senses are the windows in which our mind perceives the world around us. There is a tendency to think that our senses provide our mind a transparent and unobstructed view of reality. We think the red of the flower is really there and readily apparent to everyone. The call of a mockingbird is equally melodious to everyone that hears it. The smell of a cinnamon roll baking in the morning is equally sweet to every potential customer. The proverbial seeing is believing aphorism connotes this very concept. Something is not real unless it is directly sensed, but once sensed, nothing can convince us that it is not real. Unfortunately, this is not the case. Our senses filter and transform much of the world such that we are only aware of a small fraction of reality.

To be fair to modern neuroscience, we don’t smell with our noses or see with our eyes. The process of seeing, hearing, smelling, and the other senses arises from the brain. Stimuli are captured and filtered by our noses, eyes, and ears, but putting all those sensory stimuli together into a coherent framework is done by all of the neural connections within our brain. What this means is that the real world, the world that generates all of those wonderful smells and sounds, is a construct of our mind based off of information that has been transformed, filtered, and, in some cases, rejected by the neural circuitry even before that information reaches our central processing. Remember the kid’s game called telephone or whisper down the alley? This is a game where one person tells something to another person. This person then tells another and so on. At each step of the retelling, the original information gets slightly altered such that at the end of the game the final sentence is nothing like the original. We play this game as adults, except we call it gossip.

The connection from the real world to our brain’s construction of the real world is similar to the telephone (or gossip) game that has been finely tuned by natural selection. Our brain, and those of every animal on the planet, has filters and transformations that supply information to the brain. Except that this information is not what objective reality is; these filters supply what the brain needs to perceive in order to survive which is specific to the individual. This singular idea sets the notion seeing is believing right on its head. We don’t see the world as it is, we see the world as we believe it is. How about an example to illustrate this point?

Many visual systems have a special set of neural connections that enhances edge detection. Edge detection is performed when animals are attempting to determine where one object stops and another one starts, like a single tree against a forest or the corner of a wall seen against another wall. Edge detection is an important part of our visual world as it enhances the distinctiveness of objects. A moment’s glance around the room or place that you are sitting in will provide you with many examples of edges being artificially enhanced by your brain’s filters. As I type this, I am sitting at my desk and viewing at least 30 different edges around me: my computer monitor, the phone, a stack of sticky notes, a stapler, bookmarks, and all sorts of other objects have a distinct line between themselves and the object next to or beneath them.

Edge detection can be performed by a simple process known as lateral inhibition. Imagine a nice neat row of photoreceptors like a line of tubas in a marching band, all of them ready to be excited by light. In addition to this line, each photoreceptor has a neural connection to its immediate neighbors on the left and right. Lateral inhibition works through this connection. When a photoreceptor is excited, it sends a signal laterally through the connection to its neighbors which inhibits them from being excited. In our marching band example, our row of tubas are quietly playing a song. At one point in the song, a spot light focuses on the middle tuba player which causes her to play really loud. In addition to her playing, she throws pieces of foam in the tubas to the right and left of her to quiet them down. Because her neighbors are not playing, her tuba (without the foam) stands out, nice and loud. Her immediate neighbors are very quiet because they have foam (inhibition) in their tubas. Tubas that are two spots away do not have any foam, so their background playing is unaffected. If we were to measure the loudness along our line of tubas, we would detect a medium intensity sound from most of the tubas until we come to the inhibited player. Here the sound would drop to a very quiet level and then jump to loud sound for the tuba in the spotlight. The change in sound between the spotlighted tuba and its neighbor has been enhanced by the lateral inhibition.

If we widen the spotlight to include other tubas along the row to maybe five other tubas, a second feature of lateral inhibition is found. Again, if we measure the sound of our tuba players from left to right, most of the tubas are playing a medium volume until we get to the first tuba at the edge of the spotlight. The tuba in the dark is being inhibited by the spotlighted tuba as covered above. The first tuba in the spotlight is only inhibited by its neighbor further in the spotlight. The second (third and fourth) tuba is inhibited by both of its neighbors in the spotlight. So the middle tubas are playing loudly, but more quietly than the first tuba at the edge of the spotlight because they receive inhibition by two tubas. The last tuba in the spotlight is identical to the first tuba in that she is only inhibited by one other player. In this scenario, the loudest tubas are in the light at the edge of the spotlight, and the quietest tubas are in the dark at the edge of the spotlight. In our marching band, the spotlight edge is evident by the difference between the loudest and quietest tubas. In vision, edges are enhanced by lateral inhibition, by making the photoreceptors at the edge of the shapes of objects either more excited (if they are in the light) or more inhibited (if they are in the dark).

Again, this filter (lateral inhibition) has augmented an important pattern in nature because the detection of edges has survival value. There is more about the different filters that are associated with our visual world (and other sensory worlds) in other chapters. The main point of this description is to demonstrate that our brain sees one phenomenon (enhanced edges) that is not really there. In a way, our eyes and brain, along with the many filters in between, have created a useful illusion of reality. These filters create or enhance one aspect of the world but, by their very design, diminish other aspects of the sensuous world. Given this, one wonders if reality is in actuality possible to perceive.

1.3 The Illusive World

Our brains, using the information gathered by our senses, construct a reality. I use the term a reality because I will present some evidence that a singular reality that is true for all humans does not exist. Also, given the different sensory capabilities of the organisms covered in this book, one could draw the conclusion that a singular true reality does not exist even for all of nature. This is the illusive world referred to in the book’s title. Our world is full of sensory energies (the sensuous world) that are filtered, transformed, altered, as well as combined with assumptions about how the world works to create a grand illusion that is perceived by our brain.

The old adage that seeing is believing, within a larger context, makes the fundamental assumption that we have the ability to perceive reality. When I grab a cold iced tea on a hot day, the moisture on the glass is real. The cooler temperature of the glass, compared to the air temperature, is real. The taste of the tea with a subtle hint of lemon, as I drink, is real. The actual truth of the matter is my brain recreates reality using the filtered and transformed sensory information combined with a large set of assumptions about the world to produce my individualistic reality. Imagine sitting in your car at a stoplight, and the car next to you begins to move slowly backwards. The first instinct that your brain produces is that your car is moving forward, so you hit the brake pedal harder. Another example is the old reliable trick when playing fetch with a dog. The trick where you pretend to throw the ball and the dog takes off after an imaginary throw. In these instances, the brain perceives something other than reality because the assumptions about reality overrule the actual sensory information. If we think that our intelligence would preclude us from falling for the fake throw trick, magicians fool us all the time using this same trick by pretending to either throw a card across the stage or catch just the right card out of midair. Our fallible brain, coupled with incomplete sensory input, constructs reality, and this reality is an illusion.

This concept about our ability to perceive reality is clearly demonstrated by peering into the world of magic. Magicians, in general, and illusionists, in particular, are intuitively tuned into how our sensory systems work. They hack our sensory systems and use them against us to entertain, confuse, and delight. One of the major tools in the magician’s arsenal is our sensory expectations. We experience the world based on our expectations about the world (i.e., the thrown ball trick). These expectations are based on our past experiences. For example, imagine that I am standing behind a desk with a basketball in my hands. I tell you that I am going to bounce the basketball off the floor. At this very point in time, your brain begins to develop a series of expectations about what I am about to do and, in essence, primes your sensory systems to perceive the next experience in the way that you want to perceive it. Given what you know about the basketball and floor, you would have some expectation on the height of the bounce. A quick glance at the floor should provide to you some expectation on the sound of the bounce. I can pretend to throw the ball down (but don’t), have a device that produces an appropriate bounce sound, and then pretend to bring the ball up to catch it. If done correctly, I can convince your brain that the basketball was actually bounced despite the fact that it never left my hands.

These same set of assumptions or expectations and sensory hacks are used in close up magic using cards and coins. When we see motion (a bird flying or a ball being thrown), our mind quickly sets up a predicted path of motion. Thus, we follow the bird or ball to where we are expecting it to proceed. In sleight of hand (or close up) magic, the magician creates motion in the cards or coins, and our brain begins to predict where that card or coin should go. The magician then interrupts this predicted motion. Our eyes continue along the predicted path, but the card or coin is missing. Thus, the trick is performed and the object has vanished.

Along with these sensory/brain hacks, the good magician can actually control the attention of the audience. This can be called misdirection, but this type of name really doesn’t fit the processes involved. A better concept would be awareness control. The magician gets you to focus really hard on an object or location and then narrows your awareness so much that the trick can be performed. An excellent, and non-magical, version of awareness control is demonstrated by the famous invisible gorilla trick. This interesting and enlightening experiment was first performed by Chris Chabris and Dan Simmons, and, at first glance, seems unbelievable. I have actually seen a subsequent version performed in person and was amazed at the outcome. The experiment can be set up using the following dialogue. You can tell the audience that one sex (say women) is better at paying attention than the other sex. To test this, you are going to have the audience watch a video. In the video, there are six people who are passing and bouncing two basketballs in a hallway. Half of the people are in dark t-shirts and half in white t-shirts. Your job is simple: count the number of times the basketball is passed by the people in the white t-shirt. Finally, you tell your audience to pay special attention to the passes because we want an accurate count for our experiment. Then you start the 1-min video. About halfway through the video, a person dressed in a gorilla suit casually walks across the scene. Interestingly, in the original and many replicated experiments, most individuals are so focused on the people in white and their passes that they claim not to have seen the gorilla. Some participants are quite adamant that the gorilla was not in the original video and claim that when they watch the video a second time, it is a different video. Our visual/brain system has the ability to focus so intently on those issues that are important to us (even if is told to us by a psychologist) that we filter out or ignore other aspects of our visual scene. In part, our brain was primed to focus the visual attention of the participants on the bouncing ball. So, our expectations helped create the illusion of the invisible gorilla.

When most of us think about magicians, we envision visual tricks. Yet, these same hacks of our sensory system can be performed using other sensory systems. One of the greatest performers that hacks our other sensory systems for his act is Apollo Robbins, the gentleman thief. Robbins’ act consists of a series of actions that controls your awareness such that he can steal your wallet, watch, or other belongings while he is telling you he is stealing your objects. Robbins will control your awareness by artfully pressing, compressing, or touching parts of your body so that your focus is on one part of your body, while he removes objects on other parts of your body. Thus, the mechanical sensations that he creates by touching your body allows him to control your awareness such that he controls the umwelt that your mind perceives.

Taken together, these examples should demonstrate that our sensory systems really perceive a combination of the sensory world and our expectations of the world. But why would our sensory system create illusions of reality instead of any objective reality? The simple and elegant answer is necessity. As you read the many examples of the wonderful and unique sensory abilities of animals outlined in subsequent chapters, it is helpful to keep in mind that these sensory systems are adaptations in response to needs of the individual organism. For our senses, there simply is no survival value in detecting all of the sensory information that is available from the surrounding world. There is, though, survival value in focusing our awareness on that part of the sensory world that can impact us. In addition, being able to predict the world (such as the flight of a bird or the movement of a fish) has additional survival value. Thus, we should not expect that our senses give us an objective reality. Our eyes, ears, and other avenues of perceiving the world gives us a slice of reality that our mind then creates the rest of the picture. This picture is the illusive world, which is just a fraction of the sensuous world.

1.4 What Really Is Reality?

From a philosophical and experimental perspective, many have argued that reality, as defined as an objective perceived world around us, is not even available to our mind. Our reality is one that is reconstructed from our sensory perceptions (along with its biases, filtering, and assumptions), and this reality is