Psychology : Semester I : Biological Basis of Behavior

Sections:

Introduction  |   Section 1  |  Section 2  |   Section 3 | Section 4 | Section 5 | Section 6

Psychology : Biological Basis of Behavior : Section Five Perception Look at the picture for a minute and then look away and describe it to a friend. Now look at it again.  Did you see different things in both viewings? Every time our senses get engaged, millions of pieces of information are transferred to the brain. The brain has to reassemble and make sense of the millions of pieces of information that it receives. It is similar to the brain putting together a puzzle that has millions of tiny pieces. This is the process of perception and occurs from all of our senses every second that we experience our world.   The first psychologists that studied how we organize and perceive our world were from Germany and their approach was called Gestalt psychology. Their work was done in the 1920’s and 30’s and their belief was that "the whole is greater than the sum of the parts."  This idea was that there was more to perception than just putting pieces of neural information together.  They developed a group of principles or laws that explain how we perceive our world. The first gestalt law is that of figure and ground.  This law states that we tend to see main objects first and then the surrounding environment. For example, if you look at the picture below, you first see the house and then the surroundings and detail. A second law is that of good figure.  This law states that if there are two or more stimuli present, we will see the strongest stimuli (for us) first.  When you look at the figure below, what do you see? Most perceptions start at the arrow and if you decided it was a chin, you will see the young lady (a majority of young people perceive it this way).  If you decided it was a nose, you will see an old lady.  Whichever one you see first is the good figure for you. A third law is closure.  Your mind will fill in the blanks of what is not there so that it makes sense of perception. When you look at the first figures you see a circle and a square.  The true objects are not complete, but your brain fills in the missing parts. In the second picture, if you look at it you will see a “dog” even though a dog is really not there. There are enough cues to help your brain decide on the object. A fourth Gestalt law is proximity.  We tend to group things on the basis of how close they are to each other. When we look at the example above, how would you explain it to people that cannot see it?  Most often we would explain it as alternating rows white and black dots. Two other components of the brain have an effect on our perceptions.  The first one is “set”.  Set is what we come to expect from a stimulus. We learn this through our experiences.  For example, when you come home from school, walk into the house, smell something chocolate and baked, your set tells you that dessert will be great! Likewise, you walk in and you identify the smell as liver and onions. Your set may tell you that you would prefer to have dinner at McDonald’s while someone else's set may tell them...wow, another great dinner! A second component is attention or our conscious focus on a particular stimulus. Think back to the picture at the start of this section.  If your favorite color is purple, you may have attended to the purpled colored components of the picture. Selective attention is focusing on a particular stimulus and ignoring others. Think of when your parents are talking to you and you are watching TV!  Divided attention is trying to attend to more than one stimulus at once.  Think of a new mother being able to talk on the phone and still be attentive to her newborn’s crying. There are also several other perceptual abilities that we have to consider: Shape constancy or our ability to understand that the size of an object remains the same even if the retinal image changes.  For example, if a door opens and closes, we do not perceive it as changing shape. We know it is a door and perceive it that way.  A second one is size constancy or our ability to see that an object does not change size as it gets closer or further away from us even though the image on the retina changes. People do not change to giants and midgets as they come closer or mover further away. They stay a constant size. The last perceptual experience that we need to discuss is depth perception, or the awareness of three dimensions. Depth perception is accomplished by both monocular and binocular cues. Monocular cues are what is seen by each eye separately.  The first is binocular disparity or the fact that each eye sees a slightly different image.  This concept has made “Magic Eyes” pictures so popular.  Stare into the picture not at it..do you see a large fish?  Try again. Which line is the longest and which is the shortest?        This is the Muller-Lyer illusion. It is related to depth perception.  The lines do not appear equal since the arrow turning inward makes us think that the line is shorter and the arrows turned outward make us think that the line is longer. Binocular cues are what is experienced by both eyes.  Artists use techniques to have us experience depth (three dimensions) in painting (two dimensions). Texture gradient: our eyes see things in the front clearer and objects in the distance become fuzzier.   Linear perspective: things look smaller in the distance due to converging parallel lines. Overlap: two objects that are overlapped, one in front looks closer and larger.   Try this perception crossword puzzle Next Section!

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