One of the fascinating questions of perception is this one:Why
do we perceive a world of rounded shapes, of near and far things, of depth instead of a flat world with one surface? A second, related question is: How is this accomplished?
do we perceive a world of rounded shapes, of near and far things, of depth instead of a flat world with one surface? A second, related question is: How is this accomplished?
Depth perception is made possible by various cues, signals or stimuli that provide an observer with information. Depth perception is made possible by cues arising from binocular vision and monocular vision. Binocular vision is vision with two eyes. The principal cue for depth perception associated with binocular vision is retinal disparity. The pupils of the eyes are about three inches apart. This gives the right eye a somewhat different view of a scene than the one obtained with the left eye. Notice that although you sense two images, you only perceive one. (This is another example of the difference between sensation and perception.) This is sometimes called the zipper function of the brain, the capacity of the visual portion of the cortex to integrate two images into a meaningful whole. The whole image, in part because of retinal disparity, appears to be three-dimensional.
Monocular vision is vision with one eye. If a person is deprived of binocular vision, then he or she can still perceive depth with the assistance of monocular cues. (Although the loss of the use of an eye impairs depth perception, it does not destroy it completely.) Monocular cues are available to one eye. These are the kinds of cues that give a landscape painting depth. Although you normally look at such a painting with both eyes open, in this case depth perception is not arising because of retinal disparity. Close one eye and look at the painting. The perception of depth will remain.
A first monocular cue is linear perspective, the tendency of parallel lines to seem to converge as they approach the horizon. Linear perspective was referred to earlier in connection with the Moon illusion. A second monocular cue is interposition, a cue created when one object blocks some portion of another object. If a person is standing in front of a tree, and the tree is partly blocked, it is easy to see that the tree is behind, not in front of, the person.
A third monocular cue is shadows. Shadows are differences in illumination gradients. These tend to help us see rounded surfaces as convex or concave. A fourth monocular cue is texture gradient. A texture gradient is perceived when we can see less detail in far away objects than those that are closer to us. Such a gradient appears spontguaously when we look at a field strewn with rocks. A fifth monocular cue is motion parallax, the tendency when moving forward fairly rapidly to perceive differential speeds in objects that are passing by and in those that are being approached. For example, in a traveling car, nearby telephone poles approach rapidly and then flash by. Look down the road. The telephone poles seem to be approaching slowly. If you can see telephone poles very far away, they seem to be almost stationary.
All of these monocular cues work together to enhance depth perception. Telepathy belongs to a larger category of phenomena called extrasensory perception. Extrasensory perception, or ESP, is the capacity to be aware of external events without the use of one of the conventional senses such as vision or hearing. ESP is referred to as the sixth sense, there are at least seven readily identified senses. ESP should more accurately be called the eighth sense.
There are three kinds of extrasensory perception: (1) precognition, (2) telepathy, and (3) clairvoyance. Precognition is the power to know what will happen in the future. Living almost five hundred years ago, the French physician and astrologer Nostradamus is one of the more famous individuals in history purported to have had precognitive powers.
Telepathy is the power to send and receive mental messages. The ability to read the minds of people who can‘t read yours is also considered to be a telepathic power. A spy with this ability would have a useful psychological tool.
Clairvoyance is the power to have visions and ―see something out of the range of normal vision. (The word clairvoyance has French roots meaning ―clear seeing.) Some clairvoyants are asserted to be able to give medical readings and visualize an illness in another person in the same way that an X-ray machine can. A person who can combine the two powers of precognition and clairvoyance is thought to be able to both predict and visualize future events. The term seer implies an ability to combine these powers. Although not a form of ESP, there is another power often associated with it. This is psychokinesis or PK. Psychokinesis is the power to move objects using only energy transmitted by the mind.
All four of the phenomena mentioned above are combined into a general class of mental abilities called psi powers, powers of the mind that are thought to transcend the conventional laws of physics and our ordinary understanding of natural science. Psi powers are sometimes also called ―wild talents.
It is not possible at this time to make a simple statement saying that psychology either accepts psi abilities as real or rejects them as false. It can be asserted that many psychologists—perhaps most—are unwilling to accept the reality of these phenomena. They don‘t believe that the data are sufficiently convincing. The reality of psi powers is still open to question. (Adapted: Psychology: A Self-Teaching Guide Frank J. Bruno).
(Sumber: Catatan Materi Kuliah Reading: English for Psychology of Student)
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Psikologi dan BK
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