Article 4

The Power of Perception

        We all live in this world. To live in it we have to feel it, we have to sense and perceive it. Our senses tell our brain what is going on around us. Sensation is when the sensory nerves are stimulated and the information is transmitted to the central nervous system. These stimulations are transmitted by light (vision), sound (hearing), chemicals (taste and smell) and physical (touch). The process by which the brain interprets the sensory stimulation is called perception. Without sensation or perception our brain wouldn’t be able to interpret the world. We wouldn’t be able to see, hear, feel or even communicate with each other. Perception does more than tell us what is around us. Perception allows us to see patterns, motion and can even trick our brain with illusions. Our whole world is technically an illusion. Perception just makes it more realistic.

       There are five basic senses in the body which are vision, hearing, taste, smell and touch. All of these have a specific stimulus like electromagnetic energy, sound waves, chemical substances in the air, chemical substances in the saliva and pressure on the skin. These senses also have an absolute threshold which is the weakest amount of stimulation that can be sensed. Some examples are a candle flame viewed 30 miles away on a dark night or the ticking of a watch from about 20 feet away in a quiet room. It is amazing that our brain can detect small changes in our environment but it can also differentiate small changes. An interesting illusion is the image of two squares on top of each other, on seems lighter than the other but in reality they are the same color. Because of the position of these blocks our brain tricks us into thinking one is darker. The difference threshold is the minimum amount of difference that can be detected between two stimuli. An example is differentiating two boxes that are blue but one is slightly darker than the other. Our brain is also capable of ignoring stimuli by a method called the signal detection theory in which the most important stimuli is focused on and the unnecessary stimuli is ignored.

(The five body senses)

       Vision is the sense that gives the most information to the brain than the other senses.  The colors that we see are light waves that reflect an object. In the human eye light travels through the pupil to the lens and then it is reflected onto the retina. When it reaches the optic nerve it sends the information to the brain. Photoreceptors are neurons sensitive to light which also take the information to the brain. Unfortunately not all of us have the ability to see, in the documentary there was a man who was blind but used other senses to see. What he did is that he would make a click sound which would bounce off whatever was around him therefore he could technically see what was around him. This is a technique that bats are known for doing.

       There are fifteen rules of perception which help us organize what we perceive. The first is closure which is the tendency to perceive a complete figure even if there are gaps in what your senses tell you. An example in the documentary was when they had the actors act scenes in special suits that would only show a bunch of dots. Most people were able to recognize the dots were people because of the position of the dots and their motion. Figure ground is what we perceive versus what we perceive as a background. A universal example is the image that seems like two people staring at each other and a vase at the same time. Proximity is to associate an object with another.  A great organization method that the brain uses is similarity which is the thought of similar objects belonging together. Then we have continuity which the organization of perceptions. This allows us to see smooth patterns. Common fate is to perceive that objects that are moving together belong together. An example is a group of joggers running in the same direction. One assumes that they are running together and that they are going to the same place. Movement is the perception to see an object change its position relative to other objects. Movies are a collection of photos that are progressing so rapidly that they appear to be moving. This is the illusion of stroboscopic motion. Depth is to perceive how far away something is from us. An illusion usually done in paintings is monocular cues which are when objects are farther away to make the illusion of depth. To perceive an objects size no matter how far away the object is, is called size constancy. To differentiate shadows and colors we have color and brightness constancy. When looking at a door from different angles we get the impression that the door is different sizes but shape constancy helps us know that an object is only one shape no matter the angle that it is in. Finally visual illusions are basically the brain tricking the eye or any other sense into sensing something else.

(The illusion of color)

        Perception is what allows us to live in a world full of illusions. Without perception we wouldn’t be able to do absolutely nothing. Our perception helps us get around and it also reflects learning expectations and attitudes. Without perception we would have nothing to interpret our senses and that is the same as feeling nothing.