Optical illusions

Variety and kinds of besetting illusions. Optical illusions are rife and familiar to all auditory illusions are well known. But it is hard to think of olfactory analogues (however, see Bhushan, 1995). 

When viewing cyclohexane, it s helpful to remember that the lower bond is in front and the upper bond is in back. If this convention is not defined, an optical illusion can make it appear that the reverse is true. For clarity, all cyclohexane rings drawn in thisbook will have the front (lower) bond heavily shaded to indicate nearness to the viewer. 

Be careful. The example above represents somewhat of an optical illusion. The products seem to suggest an anti addition (the methyl and the OH are trans to each other). But think about what we added in this reaction we did not add OH and a methyl group. The methyl group was already there. Rather, we added OH and H. The H that we added is not shown in the product above (because it does not have to be drawn in a bond-line drawing). If you draw that H on the compound above, you will see that it is on a dash—therefore, this was a syn addition of H and OH. 

When microscopists began to look at the tissues of living forms they already had in their minds a view of matter as an aggregate of more or less uniform microscopic components. It is therefore understandable that when they saw everywhere agglomerations of more or less spherical halations, they concluded that these optical illusions were the fundamental subunits of animate matter, and when they actually saw cells they had no idea what they were (Harris, 1999, p. 39-... 

The idea of near-field optics to bypass the diffraction limit was described in three visionary papers published by Synge in the period 1928-32. Synge s idea is illus-... 

Dennis and Vanessa were called out of the hut, and they agreed that the effect was remarkable. I wandered away as they began to speculate on the causes—the time of day, the light conditions, optical illusions, and all the rest. I seemed to have no heart for these arguments each time they broke out, I found myself with some deep, inner assurance that the situation was moving forward just as it should and that everyone was playing a part and doing it very well. 

The figure on the right has become a classic in optical illusions. Is it silhouettes of two faces, or is it a vase ... 

When this gratuitously titled machinery is set into rotary motion, the striped and displaced circles appear to undulate. This movement produces a hypnotic illusion of pulsating depth, or what Robert Lebel poetically called a screen for suggestive metamorphosis. Fascinated by this quirky optical experiment, Duchamp (especially in 1926) created a number of substitute disks decorated with either spiral-linear and colored patterns, many of which included similarly inscribed onomatopoetically, pseudo-emblematic patterns (see MD-125, MD-126, MD-135, MD-139). These motorized illusionistic doodles continued in production, culminating eventually in 1935, with the editions of some 1500, flat cardboard disks, collectively called the Rotoreliefs (MD-144). Another approach in this direction of rotary symbolism was represented in the 1926 film Anemic Cinema (MD-140), where spirals alternate with puns inscribed within slowly turning disks. ... 

The arcades are zones of special effects where optical illusions, tricks of the light and transformations readily occur. This is why the arcades appear so magical, but it also intimates something of their propensity to deception and delusion. The very magic of the space colludes with the commodity promises on sale. Walter Benjamin mentions a phosphorescent effect in an... 

Since perspective plots like those in Figures 2-4 are subject to optical illusions, instruction as to their proper viewing is necessary. The parabolic surfaces of Figures 2a, 2c, 2d, 3a, 3c, and 4a all open downward. The viewer looks at the top surface of the plot rather than at the underside. Similarly, in the more planar plots of Figures 2b, 3b, and 4b the view is of the top surface of the plots. Figure 3d, which exhibits a minimum in the activity surface (see Table XI), rises to the right. The view is again of the top surface. 

So the question naturally arises If atomic particles are so small we can t use our senses to detect them, how do we know they are there By inference. Humankind learned long ago that the input of the senses can be flawed. Optical, olfactory, and tactile illusions abound. So to discover the nature of those parts of the world that cannot be smelled, touched, and seen, people have learned to look at secondary effects and infer their causes. The concept was well captured by the venerated scientist Ernest Rutherford in the advice he gave to James Chadwick when Chadwick was looking for evidence for the neutron. Rutherford advised. 

One groLi]) of schemes advocated soft hues and subtle textures, with the emphasis on precise colour blending, to create an optical illusion simulating invisibility. Others... 

The ision ])rocess is tlierefore prone to various influences which can affect the perception of detail, briglitness, contrast and colour. Through tests such as those used to examine for colour blindness, the Camouflage Section was able to identify optical illusion-type effects and other methods of visual confusion utilising particular mixes of colours, all of which were incorporated in systems of protective painting for ships. 

Use of optical methods in NSOM is often objectionable because of the interference of stray light on the image signal (a moot point in SECM), difficulty with liquid operation, and difficulty with miniaturization. Karra i and Grober developed a nonoptical method, which employs a miniature tuning fork as the vibration amplitude detector (51,52). Figure 8A is an illus-... 

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