Hockenbury Discovering Psychology 5th txtbk

88 CHAPTER 3 Sensation and PerceptionA Little Bit of Vision . . . Although Mikecould “see” from the moment the bandageswere removed from his eye (left), hestill had trouble identifying objects, especiallystationary ones. Mike tells this storyof a walk down an unfamiliar street inBarcelona, Spain: “I picked my waythrough some street construction. I saw afluorescent green object in my path andtapped it with my cane. It wasn’t hard likea sign so I tapped it a bit harder as I stillcouldn’t figure out visually what it was. Iwas startled as a burst of Spanish profanitycame from the workman bent over diggingout a hole in the sidewalk. He didn’ttake too kindly to me poking him in thebehind with my cane. A little bit of visioncan be dangerous sometimes” (May, 2004).But what did Mike see? Anatomically, hisright eye was now normal. But rather thanbeing 20/20, his vision was closer to20/1,000. What that means is his view ofthe world was very blurry. He could seecolors, shapes, lines, shadows, light anddark patches. So why wasn’t the worldcrystal clear?Although the structures of his eye wereworking, his brain did not know how tointerpret the signals it was receiving.As neuropsychologist Ione Fine (2002)explained, “Most people learn the languageof vision between the age of birthand two years old. Mike has had to learn itas an adult.” Indeed, there is much moreto seeing than meets the eye.Faces posed a particular challenge forMike. During conversations, he found it verydistracting to look at people’s faces. As Mikewrote in his journal, “I can see their lipsmoving, eyelashes flickering, head nodding,and hands gesturing. It was easiest to closemy eyes or tune out the visual input. Thiswas often necessary in order to pay attentionto what they were saying” (May, 2004).And what was it like the first time hewent skiing, just weeks after his surgery?Mike was dazzled by the sight of thetall, dark green trees, the snow, and the distantpeaks against the blue sky (May, 2004).But although you might think that vision,even blurry vision, would be a distinct advantageto an expert skier, this was not thecase. Mike found it easier to ski with hiseyes closed, with Jennifer skiing ahead andshouting out directions. With his eyes open,he was overwhelmed by all the visual stimuliand the frightening sense that objects wererushing toward him. “By the time I thoughtabout and guessed at what the shadows onthe snow meant, I would miss the turn orfall on my face. It was best to close myeyes,” he explained.Throughout this chapter, we will comeback to Mike’s story. We’ll also tell youwhat neuropsychologists Ione Fine andDon MacLeod learned after conductingfMRI scans of Mike’s brain. And, later inthe chapter, we’ll see how well you do atdeciphering some visual illusions as comparedto Mike.>> Introduction:What Are Sensation and Perception?Glance around you. Notice the incredible variety of colors, shades, shadows, andimages. Listen carefully to the diversity of sounds, loud and soft, near and far. Focuson everything that’s touching you—your clothes, your shoes, the chair you’re sittingon. Now, inhale deeply through your nose and identify the aromas in the air.With these simple observations you have exercised four of your senses: vision,hearing, touch, and smell. As we saw in Chapter 2, the primary function of the nervoussystem is communication—the transmission of information from one part of thebody to the other. Where does that information come from? Put simply, your sensesare the gateway through which your brain receives all its information about theenvironment. It’s a process that is so natural and automatic that we typically take itfor granted until it is disrupted by illness or injury. Nevertheless, as Mike’s storydemonstrates, people with one nonfunctional sense are amazingly adaptive. Often,they learn to compensate for the missing environmental information by relying ontheir other senses.