What we See & What we Observe!
Description of illusion;
||That the ancients sensed the existence or possibility of optical illusions is evidenced by the fact that they tried to draw and to paint although their inability to observe carefully is indicated by the absence of true shading. The architecture of ancient Greece reveals knowledge of certain optical illusions in the efforts to overcome them. However, the study of optical illusions did not engage the attention of scientists until a comparatively recent period.
Undoubtedly, thoughtful observers of ages ago would have noticed optical illusions, especially those found in architecture and nature. When it is considered that geometrical figures are very commonly of an illusory character it appears improbable that optical illusions could have escaped the keenness of Euclid. The apparent enlargement of the moon near the horizon and the apparent flattened vault of the sky were noticed at least a thousand years ago and literature yields several hundred memoirs on these subjects.
The purpose of visual processing is to take in information about the world around us and make sense of it. Vision involves
the sensing and the interpretation of light. The visual sense organs are the eyes, which convert incoming light energy into electrical signals.
However, this transformation is not vision in its entirety. Vision also involves the interpretation of the visual stimuli and the processes of perception and ultimately cognition.
The visual system has evolved to acquire veridical information from natural scenes. It succeeds very well for most tasks. However, the information in visible light sources is often ambiguous; and to correctly interpret the properties of many scenes, the visual system must make additional assumptions about the scene and the sources of light. A side effect of these assumptions is that our visual perception cannot always be trusted. Visually perceived imagery can be deceptive or misleading. As a result, there are situations where seeing is not believing, i.e., what is perceived is not necessarily real. These misperceptions are often referred to as illusions.
Physical illusions are those due to the disturbance of light between objects and the eyes, or due to the disturbance of sensory signals of the eyes (also known as physiological illusions). Cognitive illusions are due to misapplied knowledge employed by the brain to interpret or read sensory signals. For cognitive illusions, it is useful to distinguish specific knowledge of objects from general knowledge embodied as rules.
An important characteristic of all illusions is that there must be some means for demonstrating that the perceptual system is somehow making a mistake.
Usually this implies that some aspect of the scene can be measured in a way that is distinct from visual perception (e.g., can be measured by a photometer, a spectrometer, a ruler, etc.). It is important to recognize that these mistakes may actually be useful features of the visual system in other contexts because the same mechanisms underlying an illusion may give rise to a veridical percept for other situations. An illusion is only an illusion if the mistakes are detectable by other means.
The visual system processes information at many levels of sophistication. At the retina, there is low-level vision, including light adaptation and the center-surround receptive fields of ganglion cells. At the other extreme, there is high-level vision, which includes cognitive processes that incorporate knowledge about objects, materials and scenes. In between there is mid-level vision. Mid-level vision is simply an ill-defined region between low and high. The representations and the processing in the middle stages are commonly thought to involve surfaces, contours, grouping and so on. Lightness perception seems to involve all three levels of processing.
The low-level approach to lightness is associated with adaptation and local interactions at a physiological level, as the crucial mechanisms. This approach has long enjoyed popularity because it offers an attractive connection between physiology and psychophysics. The high-level approach is historically associated with the product of unconscious inference. What we perceive is our visual system's best guess as to what is in the world. The guess is based on the raw image data plus our prior experience.
The eye is a fantastic organ being very complex in construction, even though we only need to know about a few of its structures. Light enters the eye through the cornea; a tough transparent tissue covering the front of the eye. It then passes through the pupil—the black hole in the middle of the colored part of the eye (the iris). The lens then focuses the light on the retina, which contains the photoreceptors—light-sensitive cells called rods and cones.
The electro-magnetic energy that we know as light energy is converted by the rods and cones into electro-chemical nerve impulses. This allows the visual information to travel along the fibers of the optic nerve onto the brain.
The next task for the rods and cones is to send the nerve impulses along the optic nerve to the primary visual cortex in the occipital lobes, at the very back of the brain where specialized receptor cells respond as the process of visual perception continues.
We can’t possibly pay attention to all the millions of stimuli that enter the eye at the same time, so we pick out the ones that are important to us and pay attention to those. At this stage of the process, the image is broken up by specialized cells called feature detectors. Feature detectors are cells that individually
respond to lines of a certain length, lines at a certain angle or lines moving in a certain direction.
When visual information reaches the brain (visual cortex), it is reorganized so that we can make sense of it. We do this by using certain visual perceptual principles: perceptual constancies, Gestalt principles, depth and distance cues.
Once the image is reassembled using these principles, it travels along two pathways simultaneously: to the temporal lobe, to identify the object and to the parietal lobe, to judge where the object is in space in relation to our visual field and our selves.
The process whereby the visual stimulus object is given meaning. The temporal lobes identify what the object is by comparing incoming information with information already stored in memory.
The more familiar we are with the observed object, the more likely it is that we will maintain perceptual constancy of it.
Size constancy: This term refers to the fact that we maintain a constant perception of an object’s size even though the size of the image on the retina alters as the object moves nearer to
or further from us.
Shape constancy: An object is perceived to maintain its known shape despite the changing perspective from which it is observed. This is a learnt skill. A toddler may have difficulty perceiving a
familiar toy if it is viewed from an unusual angle.
Depth and distance cues are vital to us. This is because we exist in a three-dimensional world but have only two-dimensional images on our two retinas from which to judge depth and distance.
Optical illusions are legion. They greet the careful observer on every hand. They play a prominent part in our appreciation of the physical world. Sometimes they must be avoided, but often they may be put to work in various arts. Their widespread existence and their forcefulness make visual perception the final judge in decoration, painting, architecture, landscaping, lighting and in other activities. The ultimate limitation of measurements with physical instruments leaves this responsibility to the intellect. The mental being is impressed with things as perceived, not with things as they are. It is believed that this intellectual or judiciary phase which plays such a part in visual perception will be best brought out by examples of various types of static optical illusions coupled with certain facts pertaining to the eye and to the visual process as a whole.
In vision, judgments are quickly made and the process apparently is largely outside of consciousness. Higher and more complex visual judgments pass into still higher and more complex intellectual judgments. All these may appear to be primary, immediate, innate, or instinctive and therefore, certain, but the fruits of studies of the psychology of vision have shown that these visual judgments may be analyzed into simpler elements. Therefore, they are liable to error.
Do you have a fascination with Einstein's theory of relativity? What I mean is, do you find yourself fascinated by the weird predictions of this theory and would you like to get to the bottom of it once and for all? While relativity Is not a light read, pieces of it can be easily understood. This is particularly the case with Special Relativity.
We attempt to explain in an intuitive way, why the time of a rapidly traveling object seems (from your point of view) to slow down. That is, why an object seems to age more slowly when it travels at very high speeds.
Our brains are wired for survival purposes for a 3 dimensional and very slow moving environment. Compared to the speed of light, the everyday objects that our brains perceive and reason about are barely moving at all. Our common sense about how the world works is specialized for dealing with an almost non-moving or static environment (again, that's compared to the speed of light).
What this means, is that what our common sense tells us about our sluggish everyday world is mostly correct but otherwise its judgements cannot be trusted when dealing with extremely fast things.
So when experiments and mathematics tell us things that are contrary to our crude perceptions about how things should work, we find it to be totally bizarre.
Our everyday common sense tells us that if while standing on a moving barge we hit a golf ball off the front, the speed of the barge adds to the speed of the golf ball. If we were to shine a flashlight in the same direction as we had hit the ball we would find that the speed of the barge does not add to the speed of the light beam. Its speed would be the same as if the barge were not moving at all.
In 1905, Einstein explained that this was simply the way that light behaved and that it only seemed strange because our common sense notions of how relative speeds were supposed to add up were only true for very slow moving objects (as compared to the speed of light).
Alternatively, if we know about the physics of water, air and light, we can explain the effect in terms of air blowing across a water surface and producing ripples, which produce a rippling effect. However, since we cannot predict precisely how gusts of air will cause a certain pattern of ripples to be in, say, one hour's time, the "classical" explanation may not be any more accurate than the abstract quantum mechanical description, and if we do not know about the precise behavior of air and water (or do not know whether these are the real cause of what we see), the QM description may be seen as more efficient. Where the interpretative approach scores is in its ability to deal robustly with a wider range of dynamic situations it allows us to immediately imagine the sort of image that should result if we throw a stone at the reflected image: using a quantum description, the calculations might be theoretically possible, but might be unmanageably complex, and it might be difficult to be certain whether or not the calculations had been done correctly and how far they could be trusted, or how their results could be visualized.
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But There is no illusion actually, unless for weak mind…
If you concentrate on illusionary images you can understand what are they?!
There is just visual effect always base on different colors that mixed together to interact and make illusion image on our brain. All of us have experience of illusionary Because always there is new structure presented by artists. But concentrate on an image and look at it several times and zoom on different part of it after few days it becomes like normal image or with less effect on your mind.
And illusionary happens because of holographic structure of our brain. Brain, automatically, tries to combine colors or texts and fix some sketchy parts. So make new image on brain thats because we cannot understand it exactly.
Also illusionary effect on scientific observations & results. Base on viewpoint of Relativity to observe an object it s important how you observe it!
Different frame effect on your measurement. So I know what that you cannot even see!
It s type of illusion for you in my frame. We can define some solutions for it; Be patient!
First try to measure from different frames carefully then collect the results & then talk about it.
Some results of Relativity are not scientific. They are just illusion. Like change in length on high speed & …
