A false awakening is an event in which someone dreams they have awoken from sleep. This illusion of having awakened is very convincing to the person. After a false awakening, people will often dream of performing daily morning rituals, believing they have truly awakened. A dream in which a false awakening takes place is sometimes colloquially referred to as a double dream, or a dream within a dream.

It may occur either following an ordinary dream or following a lucid dream, one in which the dreamer has been aware of dreaming. Particularly if the false awakening follows a lucid dream, the false awakening may turn into a pre-lucid dream, in which the dreamer may start to wonder if they are really awake and may or may not come to the correct conclusion.

A false awakening has significance to the simulation hypothesis which states that what we perceive as true reality is in fact an illusion as evidenced by our minds’ inability to distinguish between reality and dreams. Therefore, advocates of the simulation hypothesis argue that the probability of our true reality being a simulated reality is affected by the prevalence of false awakenings.

Certain aspects of life may be dramatized or out of place in false awakenings. Details like being able to see a painting on a wall, not being able to talk or difficulty reading are common. In some experiences, the human senses are heightened or changed. For instance, one may be able to see things in greater detail, or lesser detail, or one may feel an intense burst of fear and anxiety, or possibly pleasure.

Because the dreamer is still dreaming after a false awakening, it is possible for there to be more than one false awakening in a single dream. Often, dreamers will seem to have awakened, begin eating breakfast, brushing teeth, and so on and then find themselves back in bed, begin daily morning rituals, believe that they have awakened again, and so forth. The French psychologist Yves Delage reported an experience of his own of this kind, in which he experienced four successive false awakenings. The philosopher Bertrand Russell claimed to have experienced about a hundred false awakenings in succession while coming round from a general anaesthetic.

The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore any state that is dependent on our senses should at the very least be carefully examined and rigorously tested to determine if it is in fact reality.

While people dream, they usually do not realize they are dreaming. This has led philosophers to wonder whether one could actually be dreaming constantly, instead of being in waking reality (or at least that one can’t be certain that he or she is not dreaming). Having received serious attention in René Descartes’ Meditations on First Philosophy, the dream argument has become one of the most popular skeptical hypotheses.

Dreaming provides a springboard for those who question whether our own reality may be an illusion. The ability of the brain to trick itself into believing a neuronally generated world is the real world means at least one variety of simulated reality is a common, even nightly event.

Those who argue that the world is not simulated must concede that the mind, at least the sleeping mind, is not itself an entirely reliable mechanism for attempting to differentiate reality from illusion.

This could be seen as a challenge to those who claim a simulated reality requires highly advanced scientific technology, since, if dreaming really is a form of virtual reality, the only apparatus needed to construct a simulated reality capable of fooling the unconscious mind is a human brain.

In Lewis Carroll’s Through the Looking-Glass, Alice finds the Red King asleep in the grass. Tweedledum and Tweedledee tell her that the Red King is dreaming about her, and that if he were to wake up she would “go out—bang!—just like a candle.”

The Polyphemus moth, Antheraea polyphemus, is a North American member of the family Saturniidae, the giant silk moths. It is a tan colored moth, with an average wingspan of 6 inches. The most notable feature of the moth is its large, purplish eyespots on its two hindwings. The eye spots are where it gets its name, from the Greek myth of the Cyclops Polyphemus. The caterpillar of the Polyphemus moth can eat 86,000 times its weight in a little less than two months. It is widespread throughout much of North America, from southern Canada to parts of Mexico.

The Polyphemus moth uses defense mechanisms to protect itself from predators. One of its most distinctive mechanisms is a distraction pattern that serves to confuse, or simply distract, predators. This involves the large eyespots on its hindwing. Eyespots are also startle patterns, a subform of distraction patterns, used for camouflage via deceptive and blending coloration. Most startle patterns are brightly colored areas on the outer body of already camouflaged animals.

Another example of the use of startle patterns is the gray tree frog, with its bright yellow leggings. When it leaps, a flash of bright yellow appears on its hindlegs, usually startling the predator away from its prey. It is believed that distraction patterns are a form of mimicry, meant to misdirect predators by markings on the moths’ wings.

Pests of the moths can become a problem. Parasitic insects such as some species of wasps and flies lay their eggs in or on the young caterpillars. The eggs then hatch into larvae which consume the insides of the caterpillars. Once the caterpillars pupate, the larvae themselves pupate, killing the pupa. Squirrels have also been known to consume the pupae of polyphemus moths, decreasing the population greatly. Pruning of trees and leaving outdoor lights on at night can also be detrimental to the polyphemus moths.

Nondualism may be viewed as the understanding or belief that dualism or dichotomy are illusory phenomena. It is accessible as a belief, theory, condition, as part of a tradition, as a practice, or as the quality of union with reality. A nondual philosophical or religious perspective or theory maintains that there is no fundamental distinction between mind and matter, or that the entire phenomenological world is an illusion 

Many traditions state that the true condition or nature of reality is nondualistic, and that these dichotomies are either unreal or inaccurate conveniences. While attitudes towards the experience of duality and self may vary, nondual traditions converge on the view that the ego, or sense of personal being and control, is ultimately an illusion. As such many nondual traditions have significant overlap with mysticism.

It should be pointed out that there can be no such thing as a nondual perspective or theory or experience, only a realization of Oneness or nonduality. One cannot accurately claim to experience nonduality, because the concept of experience depends on the subject-object distinction, which is a duality. The subject experiences an object, which is something separate from the subject. This is incompatible with a truly nondual realization. Thus there cannot truly be an accurate verbal account of this union, only words that insufficiently point to the realization.

All schools of Buddhism teach “no-self”, or pali anatta. It is the non-duality of subject and object, which is very explicitly stated by the Buddha in verses such as “In seeing, there is just seeing. No seer and nothing seen. In hearing, there is just hearing. No hearer and nothing heard.”

Dzogchen is a relatively esoteric tradition concerned with the natural state, emphasizing direct experience. The Dzogchen practitioner realizes that appearance and emptiness are inseparable. One must transcend dualistic thoughts to perceive the true nature of one’s pure mind. This primordial nature is clear light, unproduced and unchanging, free from all defilements. One’s ordinary mind is caught up in dualistic conceptions, but the pure mind is unafflicted by delusions.

Through meditation, the Dzogchen practitioner experiences that thoughts have no substance. Mental phenomena arise and fall in the mind, but fundamentally they are empty. The practitioner then considers where the mind itself resides. The mind can not exist in the ever changing external phenomena and through careful examination one realizes that the mind is emptiness. All dualistic conceptions disappear with this understanding.

Zen is a non dual tradition. It can be considered a religion, a philosophy, or simply a practice depending on one’s perspective. It has also been described as a way of life, work, and an art form. Zen practitioners deny the usefulness of such labels, calling them, “The finger pointing at the moon.”

Sikhism is a monotheistic religion which hold the view of non dualism. A principle cause of suffering in Sikhism is the ego, the delusion of identifying oneself as an individual separate from the surroundings. From the ego arises the desires, pride, emotional attachments, anger, lust, etc., thus putting humans on the path of destruction. According to Sikhism the true nature of all humans is the same as God and everything that originates with God. The goal of a Sikh is to conquer the ego and realize true nature or self, which is the same as God’s.

The Hering illusion is an optical illusion discovered by the German physiologist Ewald Hering in 1861. The two lines are both straight, but they look as if they were bowing outwards. The distortion is produced by the lined pattern on the background, that simulates a perspective design, and creates a false impression of depth.

The Hering illusion looks like bike spokes around a central point, with lines on either side of this central, so called vanishing point. The illusion tricks us into thinking we are moving forward. Since we aren’t actually moving and the figure is static, we misperceive the straight lines as curved ones.

Researcher Mark Changizi of Rensselaer Polytechnic Institute in New York says optical illusions are due to a neural lag which most humans experience while awake. When light hits the retina, about one tenth of a second goes by before the brain translates the signal into a visual perception of the world. Scientists have known of the lag, yet they have debated over how humans compensate, with some proposing that our motor system somehow modifies our movements to offset the delay.

Changizi asserts that the human visual system has evolved to compensate for neural delays, generating images of what will occur one tenth of a second into the future. This foresight enables human to react to events in present. This allows humans to perform reflexive acts like catching a fly ball and to maneuver smoothly through a crowd. Illusions occur when our brains attempt to perceive the future, and those perceptions don’t match reality. The Hering illusion tricks us into thinking we are moving forward, and thus, switches on our future seeing abilities. Since we aren’t actually moving and the figure is static, we misperceive the straight lines as curved ones.

Chnagizi says, ”Evolution has seen to it that geometric drawings like this elicit in us premonitions of the near future. The converging lines toward a vanishing point are cues that trick our brains into thinking we are moving forward as we would in the real world, where the pair of lines seems to bow out as we move through it, and we try to perceive what that world will look like in the next instant.”

Imagination is the faculty of forming mental images or concepts of what is not actually present to the senses, and the action or process of forming such images or concepts. The common use of the term is for the process of forming in the mind new images which have not been previously experienced, or at least only partially or in different combinations. 

It helps provide meaning to experience and understanding to knowledge. It is a fundamental facility through which people make sense of the world and it also plays a key role in the learning process. A basic training for imagination is listening to storytelling narrative, in which the exactness of the chosen words is the fundamental factor to evoke worlds.

When two existing perceptions are combined within the mind the resultant third perception is referred to as its synthesis, and on occasion a fourth perception called the antithesis can often become the inspiration for a new invention or technique. It has been proposed that the whole of human cognition is based upon imagination. In a sense, nothing we perceive is purely observation but is a morph between sense and imagination.

Some cultures and traditions view the apparently shared world as an illusion of the mind as with the Buddhist maya, or go to the opposite extreme and accept the imagined and dreamed realms as of equal validity to the apparently shared world as the Australian Aborigines do with their concept of dreamtime.

The world is an interpretation of data arriving from the senses. As such it is perceived as real by contrast to most thoughts and imaginings. This difference is very slight and can be altered by several historic causes, namely changes to brain chemistry, hypnosis or other altered states of consciousness, meditation, hallucinogenic drugs, and electricity applied directly to specific parts of the brain.

Imagination, because of having freedom from external limitations, can become a source of real pleasure or unnecessary suffering. A person of vivid imagination often suffers acutely from the imagined perils besetting friends, relatives, or even strangers such as celebrities. Crippling fear can result from taking an imagined painful future too seriously.

Imagination can also produce some symptoms of real illnesses. In some cases, they can seem so real that specific physical manifestations occur such as rashes and bruises appearing on the skin, as though imagination had passed into belief or the events imagined were actually in progress. 

One hypothesis for the evolution of human imagination is that it allowed conscious beings to solve problems and increase an individual’s survival by use of mental simulation. Most famous inventions or entertainment products were created from the inspiration of one’s imagination.

Entoptic phenomena are visual effects whose source is within the eye itself. They have a physical basis in the image cast upon the retina. Hence, they are different from optical illusions, which are perceptual effects that arise from interpretations of the image by the brain. Because entoptic images are caused by phenomena within the observer’s own eye, they share one feature with optical illusions and hallucinations: the observer cannot share a direct and specific view of the phenomenon with others.

In 1851 Hermann Helmholtz commented on phenomena which could be seen easily by some observers, but could not be seen at all by others. This variance is not surprising because the specific aspects of the eye that produce these images are unique to each individual. Because of the variation between individuals, and the inability for two observers to share a nearly identical stimulus, these phenomena are unlike most visual sensations. They are also unlike most optical illusions which are produced by viewing a common stimulus. Yet, there is enough commonality between the main entoptic phenomena that their physical origin is now well understood.

Floaters or muscae volitantes are slowly drifting transparent blobs of varying size and shape, which are particularly noticeable when lying on the ground looking up at the sky. They are caused by imperfections in the fluid of the eye.

The blue field entoptic phenomenon has the appearance of tiny bright dots moving rapidly along squiggly lines in the visual field. It is much more noticeable when viewed against a field of pure blue light and is caused by white blood cells moving in the capillaries in front of the retina.

Haidinger’s brush is a very subtle yellow and blue pattern that is seen when viewing a field of light that is polarized.

The Purkinje tree is an image of the retinal blood vessels in one’s own eye. It can be seen by shining a bright, moving light like a penlight onto the sclera (the white of the eye) in a darkened room. Normally the image of the retinal blood vessels is invisible because of adaptation. The unusual angle casts the image onto unadapted portions of the retina. Unless the light moves, the image disappears within a second or so. If the light is moved at about 1 Hz, adaptation is defeated, and a clear image can be seen indefinitely. The vascular figure is often seen by patients during an ophthalmic examination when the doctor is using an ophthalmoscope. In the process of aligning the instrument so that the doctor can view the blood vessels through the pupil, the light from the instrument often falls briefly on the sclera, so that the patient gets a quick glimpse of the vascular figure.

A phosphene is the perception of light without light actually entering the eye, for instance caused by pressure applied to the closed eyes.

During the 1920s, some theosophists, unaware of the physical explanation, maintained that the moving spots seen in the blue field entoptic phenomenon were vitality globules related to the concept of prana in yoga.

The Muller-Lyer illusion is an optical illusion consisting of nothing more than an arrow. It consists of two arrow like figures, one with both ends pointing in, and the other with both ends pointing out. When asked to judge the lengths of the two lines, which are equal, viewers will typically claim that the line with inward pointing arrows is longer.

One possible explanation is that one sees the lines as three dimensional, such as the outgoing and ingoing corners of a room. Another possible explanation is that the line with arrows pointing inwards may simply appear longer because the arrows themselves extend past the line.

The illusion is not cross cultural. Non western subjects, and particularly subjects whose day to day surroundings are usually not rectangular, as with few buildings, doors, walls, are much less likely to be affected by it. Researchers discovered that the Zulu people, whose typical dwellings are circular thatched huts with no angular walls, were rarely susceptible to the illusion.

One possible explanation states that the Muller-Lyer illusion occurs because the visual system processes that judge depth and distance assume in general that the angles in configuration corresponds to an object which is closer, and the angles out configuration corresponds to an object which is far away. Basically, there seems to be a simple heuristic that takes those configurations as 90 degree angles. This heuristic speeds up the interpretation process, but gives rise to many optical illusions in unusual scenes.

Neural nets in the visual system of human beings learn how to make a very efficient interpretation of 3D scenes. That is why, when somebody goes away from us, we do not see him getting shorter. And when we stretch one arm and look at the two hands we do not see one hand smaller than the other. We should not forget that, as visual illusions show us quite clearly, what we see is an image created in our brain. Our brain projects the image of the smaller hand to its correct distance in our internal 3D model. This is what is called the size constancy mechanism.

In the Muller-Lyer illusion, the visual system detects the depth cues, which are usually associated with 3D scenes, and incorrectly decides it is a 3D drawing. Then the size constancy mechanism makes us see an erroneous length of the object which, for a true perspective drawing, would be further away.