Hockenbury Discovering Psychology 5th txtbk

Perception113Table 3.4Summary Table of the SensesSense Stimulus Sense Organ Sensory Receptor CellsHearing (audition) Sound waves Ear Hair cells in cochleaVision Light waves Eye Rods and cones in retinaColor vision Different wavelengths of light Eye Cones in retinaSmell (olfaction) Airborne odor molecules Nose Hairlike receptor cells at top of nasal cavityTaste (gustation) Chemicals dissolved in saliva Mouth Taste budsTouch Pressure Skin Pacinian corpusclePain Tissue injury or damage; varied Skin, muscles, and organs NociceptorsMovement (kinesthetic sense) Movement of the body None; muscle and joint Proprioceptors in muscle and joint tissuetissueBalance (vestibular sense) Changes in position, gravity Semicircular canals and Hairlike receptor cells in semicircular canalsvestibular sacsand vestibular sacsPerceptionKey Theme• Perception refers to the process of integrating, organizing, and interpretingsensory information into meaningful representations.Key Questions• What are bottom-up and top-down processing, and how do they differ?• What is Gestalt psychology?• What Gestalt principles explain how we recieve objects and theirrelationship to their surroundings?As we’ve seen, our senses are constantly registering a diverse range of stimuli from theenvironment and transmitting that information to the brain. But to make use of this rawsensory data, we must organize, interpret, and relate the data to existing knowledge.Psychologists sometimes refer to this flow of sensory data from the sensory receptorsto the brain as bottom-up processing. Also called data-driven processing,bottom-up processing is often at work when we’re confronted with an ambiguousstimulus. For example, imagine trying to assemble a jigsaw puzzle one piece at atime, without knowing what the final picture will be. To accomplish this task, youwould work with the individual puzzle pieces to build the image from the “bottomup,” that is, from its constituent parts.But as we interact with our environment, many of our perceptions are shaped bytop-down processing, which is also referred to as conceptually driven processing.Top-down processing occurs when we draw on our knowledge, experiences, expectations,and other cognitive processes to arrive at meaningful perceptions, such aspeople or objects in a particular context.Both top-down and bottom-up processing are involved in our everyday perceptions.As a simple illustration, look at the photograph (right), which sits on Don’s desk. Topdownprocessing was involved as you reached a number of perceptual conclusions aboutthe image. You quickly perceived a little girl holding a black cat—our daughter Laurawhen she was three, holding her cat, Nubbin. You also perceived a child as a whole objecteven though the cat is actually blocking a good portion of the view of Laura.But now look at the background in the photograph, which is more ambiguous.Deciphering these images involves both bottom-up and top-down processing. Bottomupprocesses help you determine that behind the little girl looms a large, irregularlyshaped, dark green object with brightly colored splotches on it. But what is it?Organizing Sensations into MeaningfulPerceptions With virtually no consciouseffort, the psychological process of perceptionallows you to integrate, orga nize, andinterpret the lines, colors, and contours inthis image as meaningful objects—alaughing child holding a panicky black catin front of a Christmas tree. How did youreach those perceptual conclusions?