Page 228 - Understanding Psychology

The Senses
Reader’s Guide
Exploring Psychology
Seeing in the Dark
Sit yourself in total darkness, a space so dark you cannot see your hand before your face. Now hold your hand before your face and move it from side to side. You see your hand in motion.
—from A Second Way of Knowing: The Riddle of Human Perception by Edmund Blair Bolles, 1991
s Main Idea
The sense organs—the eyes, ears, tongue, nose, skin, and others—are the receptors of sensations.
s Vocabulary
• pupil
• lens
• retina
• optic nerve
• binocular fusion
• retinal disparity
• auditory nerve
• vestibular system
• olfactory nerve
• kinesthesis
s Objectives
• Describe the nature and functioning of
the sense organs.
• Identify the skin and body senses and
explain how they work.
Why did you see your hand moving even though it was totally dark while doing the experiment above? You have just experi- enced kinesthesis—one of the senses. Although people are thought to have five senses, there are actually more. In addition to vision, hearing, taste, smell, and touch, there are several skin senses and two internal senses: vestibular and kinesthetic.
Each type of sensory receptor takes some sort of external stimulus— light, chemical molecules, sound waves, and pressure—and converts it into a chemical-electrical message that can be transmitted by the nervous system and interpreted by the brain. So far, we know most about these processes in vision and hearing. The other senses have received less atten- tion and are more mysterious in their functioning.
214
Chapter 8 / Sensation and Perception