CHAPTER 4 Sensation LESSONS 4 1 Basic Principles

CHAPTER 4 Sensation LESSONS 4. 1 Basic Principles of Sensation 4. 2 Vision 4. 3 Hearing and Your Other Senses PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 1

LESSON 4. 1 Basic Principles of Sensation OBJECTIVES l Explain the concepts of sensory thresholds and compare the different theories. l Describe sensory adaptation. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 2

Sensory Thresholds l Sensation is the process that detects stimuli from your body and

Table 4 -1 The Stimuli and Sensory Receptors for Each Primary Sense Stimulus Sensory Receptors Vision Light waves Light-sensitive rods and cones in the retina of the eye Hearing Sound waves Pressure-sensitive hair cells in the cochlea of the inner ear Taste Molecules dissolved Taste cells in the taste buds of the in fluid on the tongue Smell Molecules dissolved in fluid in the nose Sensitive ends of olfactory (smell) neurons Touch Pressure on the skin Sensitive ends of touch neurons PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 4

Absolute Threshold l Absolute threshold is the weakest amount of a given stimulus that a person can detect half of the time. l Present at different intensities l Determine lowest level detectable 50 percent of the time PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 5

Table 4 -2 Examples of Absolute Thresholds Stimulus Absolute Threshold Vision A candle seen at 30 miles on a dark, clear night Hearing The tick of a watch at 20 feet under quiet conditions Taste One teaspoon of sugar in 2 gallons of water Smell One drop of perfume diffused into a threeroom apartment Touch The wing of a fly falling on your cheek from a distance of 0. 5 inch Source: Adapted from Galanter, 1962. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 6

Signal-Detection Theory l Signal-detection theory states that detecting a stimulus is influenced by a person’s decision-making strategy. l Also influenced by: l Expectations l Rewards and costs PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 7

Difference Threshold l Difference threshold is the smallest difference between two stimuli that can be detected half of the time. l Changes in strength and intensity l Ex: 1 lb vs 2 lb and 100 lb vs 101 lb PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 8

Sensory Adaptation l Sensory adaptation is the tendency for sensory receptors to decrease in response to stimuli that continue at the same level. l Ex: Get used to a smell right beside you Remove it for about 10 minutes, put it back, just as strong as the beginning PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 9

LESSON 4. 2 Vision OBJECTIVES l Identify and illustrate the structures of the eye that are responsible for vision. l Describe the way the brain perceives color. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 10

Figure 4 -1 The Electromagnetic Spectrum PSYCHOLOGY A Discovery Experience © 2011 South-Western |

Structures of the Human Eye l The pupil is an opening in the iris that allows light to enter the eye. l The iris is a ring of muscles that range in color from light blue to dark brown. l The lens is a clear, elastic, disc-shaped structure that refocuses light. l The retina is the light-sensitive surface at the back of the eye. l The optic nerve carries information from the retina to the brain. l The blind spot is the area on the retina where the optic nerve leaves the eye and that contains no receptor cells. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 12

Figure 4 -2 Major Structures of the Human Eye PSYCHOLOGY A Discovery Experience ©

Figure 4 -3 How Light Travels through the Eye PSYCHOLOGY A Discovery Experience ©

Color Vision l All the colors you see are red, blue, and green, or a mixture of these three. l The color is in your visual system. l An object appears as a particular color because it absorbs or reflects certain wavelengths of light. l Colors are created by the cones in your eye responding to wavelengths and sending neural signals to your brain, which then creates the colors you see. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 15

Color Blindness l Color blindness is a deficiency in the ability to distinguish among colors. l 1 in 50 l 90% are males PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 16

Figure 4 -4 Test for Color Blindness PSYCHOLOGY A Discovery Experience © 2011 South-Western

LESSON 4. 3 Hearing and Your Other Senses OBJECTIVES l Explain and illustrate the human auditory system and the structure of the ear. l Describe the senses of smell, taste, touch, and body position and movement. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 18

The Auditory System l The auditory system controls your sense of hearing. l Hearing begins with sound waves— vibrations in air, water, or solid material. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 19

The Auditory System—Amplitude l Loudness of sound is the height of a sound wave, called amplitude. l Amplitude is measured in decibels (d. B). l The greater the amplitude, the higher the decibels, and the louder the sound. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 20

Table 4 -3 Decibel Level of Some Common Sounds Decibels Source Exposure Danger 180 Space shuttle launch Hearing loss certain within 150 feet of launch pad 140 Jet aircraft motor Any exposure dangerous 120 Sandblaster, thunderclap Immediate danger 100 Heavy auto traffic, lawn mower 2 hours 60 Normal conversation No danger 40 Quiet office No danger 30 Quiet library No danger 20 Soft whisper No danger 0 Minimal detectable sound No danger PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 21

The Ear l The ear is divided into three major parts: l The outer ear is the part you see. l The eardrum is a thin, flexible membrane that vibrates in sequence with sound waves. l The cochlea is the coiled, fluid-filled tube in the inner ear that contains hair-like auditory receptors. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 22

Figure 4 -5 The Human Ear PSYCHOLOGY A Discovery Experience © 2011 South-Western |

New Science Sensory Crossovers PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning

Smell l The olfactory nerve transmits neural impulses containing smell information from the nose to the brain. PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 25

Figure 4 -6 The Olfactory System PSYCHOLOGY A Discovery Experience © 2011 South-Western |

Taste l Taste buds are sensory receptor organs that contain the receptor cells for

Taste Sensations l Four most familiar taste sensations: l Sweetness (mostly sugars) l Sourness (mostly acids) l Saltiness (mostly salts) l Bitterness (mainly chemicals that have no food value or are toxic) PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 28

The Skin Senses l Skin is your largest sensory organ. l The sense of touch is actually a combination of three skin senses: l Pressure l Temperature l Pain PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 29

Chapter 4 Clicker Questions 1. Which refers to nerve cells firing less frequently after high levels of stimulation? a. critical thinking b. environmental threshold c. absolute threshold d. sensory adaptation PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 30

Chapter 4 Clicker Questions 2. The major contribution of the signal-detection theory was the establishment of specific absolute thresholds for all senses. a. True b. False PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 31

Chapter 4 Clicker Questions 3. Which is a ring of muscles that range in color from light blue to dark brown? a. pupil b. iris c. lens d. retina PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 32

Chapter 4 Clicker Questions 4. Loudness of a sound corresponds to the height of a sound wave called a. amplitude b. pitch c. frequency d. timbre PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 33

Chapter 4 Clicker Questions 5. What is the term for the senses that detect body position and movement? a. olfactory b. proprioceptive c. sensorineural d. auditory PSYCHOLOGY A Discovery Experience © 2011 South-Western | Cengage Learning Chapter 4 Slide 34