# 5.E: Sensation and Perception (Exercises)

## 5.1: Sensation versus Perception

Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction.

### Review Questions

#### Q1

________ refers to the minimum amount of stimulus energy required to be detected $$50\%$$ of the time.

1. absolute threshold
2. difference threshold
3. just noticeable difference
4. transduction

#### Q2

Decreased sensitivity to an unchanging stimulus is known as ________.

1. transduction
2. difference threshold
4. inattentional blindness

#### Q3

________ involves the conversion of sensory stimulus energy into neural impulses.

2. inattentional blindness
3. difference threshold
4. transduction

#### Q4

________ occurs when sensory information is organized, interpreted, and consciously experienced.

1. sensation
2. perception
3. transduction

### Critical Thinking Question

#### Q5

Not everything that is sensed is perceived. Do you think there could ever be a case where something could be perceived without being sensed?

#### Q6

Please generate a novel example of how just noticeable difference can change as a function of stimulus intensity.

### Personal Application Question

#### Q7

Think about a time when you failed to notice something around you because your attention was focused elsewhere. If someone pointed it out, were you surprised that you hadn’t noticed it right away?

### Solution

A

C

D

B

#### S5

This would be a good time for students to think about claims of extrasensory perception. Another interesting topic would be the phantom limb phenomenon experienced by amputees.

#### S6

There are many potential examples. One example involves the detection of weight differences. If two people are holding standard envelopes and one contains a quarter while the other is empty, the difference in weight between the two is easy to detect. However, if those envelopes are placed inside two textbooks of equal weight, the ability to discriminate which is heavier is much more difficult.

## 5.2: Waves and Wavelengths

Visual and auditory stimuli both occur in the form of waves. Although the two stimuli are very different in terms of composition, wave forms share similar characteristics that are especially important to our visual and auditory perceptions. In this section, we describe the physical properties of the waves as well as the perceptual experiences associated with them.

### Review Questions

#### Q1

Which of the following correctly matches the pattern in our perception of color as we move from short wavelengths to long wavelengths?

1. red to orange to yellow
2. yellow to orange to red
3. yellow to red to orange
4. orange to yellow to red

#### Q2

The visible spectrum includes light that ranges from about ________.

1. $$400-700$$ nm
2. $$200-900$$ nm
3. $$20-20000$$ Hz
4. $$10-20$$ dB

#### Q3

The electromagnetic spectrum includes ________.

2. $$x$$-rays
3. infrared light
4. all of the above

#### Q4

The audible range for humans is ________.

1. $$380-740$$ Hz
2. $$10-20$$ dB
3. less than $$300$$ dB
4. $$20-20,000$$ Hz

#### Q5

The quality of a sound that is affected by frequency, amplitude, and timing of the sound wave is known as ________.

1. pitch
2. tone
3. electromagnetic
4. timbre

### Critical Thinking Question

#### Q6

Why do you think other species have such different ranges of sensitivity for both visual and auditory stimuli compared to humans?

#### Q7

Why do you think humans are especially sensitive to sounds with frequencies that fall in the middle portion of the audible range?

### Personal Application Question

#### Q8

If you grew up with a family pet, then you have surely noticed that they often seem to hear things that you don’t hear. Now that you’ve read this section, you probably have some insight as to why this may be. How would you explain this to a friend who never had the opportunity to take a class like this?

### Solution

B

A

C

D

D

#### S6

Other species have evolved to best suit their particular environmental niches. For example, the honeybee relies on flowering plants for survival. Seeing in the ultraviolet light might prove especially helpful when locating flowers. Once a flower is found, the ultraviolet rays point to the center of the flower where the pollen and nectar are contained. Similar arguments could be made for infrared detection in snakes as well as for the differences in audible ranges of the species described in this section.

#### S7

Once again, one could make an evolutionary argument here. Given that the human voice falls in this middle range and the importance of communication among humans, one could argue that it is quite adaptive to have an audible range that centers on this particular type of stimulus.

## 5.3: Vision

The visual system constructs a mental representation of the world around us. This contributes to our ability to successfully navigate through physical space and interact with important individuals and objects in our environments. This section will provide an overview of the basic anatomy and function of the visual system. In addition, we will explore our ability to perceive color and depth.

### Review Questions

#### Q1

The ________ is a small indentation of the retina that contains cones.

1. optic chiasm
2. optic nerve
3. fovea
4. iris

#### Q2

________ operate best under bright light conditions.

1. cones
2. rods
3. retinal ganglion cells
4. striate cortex

#### Q3

________ depth cues require the use of both eyes.

1. monocular
2. binocular
3. linear perspective
4. accommodating

#### Q4

If you were to stare at a green dot for a relatively long period of time and then shift your gaze to a blank white screen, you would see a ________ negative afterimage.

1. blue
2. yellow
3. black
4. red

### Critical Thinking Question

#### Q5

Compare the two theories of color perception. Are they completely different?

#### Q6

Color is not a physical property of our environment. What function (if any) do you think color vision serves?

### Personal Application Question

#### Q7

Take a look at a few of your photos or personal works of art. Can you find examples of linear perspective as a potential depth cue?

### Solution

C

A

B

D

#### S5

The trichromatic theory of color vision and the opponent-process theory are not mutually exclusive. Research has shown they apply to different levels of the nervous system. For visual processing on the retina, trichromatic theory applies: the cones are responsive to three different wavelengths that represent red, blue, and green. But once the signal moves past the retina on its way to the brain, the cells respond in a way consistent with opponent-process theory.

#### S6

Color vision probably serves multiple adaptive purposes. One popular hypothesis suggests that seeing in color allowed our ancestors to differentiate ripened fruits and vegetables more easily.

## 5.4: Hearing

This section will provide an overview of the basic anatomy and function of the auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses, where in the brain that information is processed, how we perceive pitch, and how we know where sound is coming from.

### Review Questions

#### Q1

Hair cells located near the base of the basilar membrane respond best to ________ sounds.

1. low-frequency
2. high-frequency
3. low-amplitude
4. high-amplitude

#### Q2

The three ossicles of the middle ear are known as ________.

1. malleus, incus, and stapes
2. hammer, anvil, and stirrup
3. pinna, cochlea, and urticle
4. both a and b

#### Q3

Hearing aids might be effective for treating ________.

1. Ménière's disease
2. sensorineural hearing loss
3. conductive hearing loss
4. interaural time differences

#### Q4

Cues that require two ears are referred to as ________ cues.

1. monocular
2. monaural
3. binocular
4. binaural

### Critical Thinking Question

#### Q5

Given what you’ve read about sound localization, from an evolutionary perspective, how does sound localization facilitate survival?

#### Q6

How can temporal and place theories both be used to explain our ability to perceive the pitch of sound waves with frequencies up to $$4000$$ Hz?

### Personal Application Question

#### Q7

If you had to choose to lose either your vision or your hearing, which would you choose and why?

### Solution

B

D

C

D

#### S5

Sound localization would have allowed early humans to locate prey and protect themselves from predators.

#### S6

Pitch of sounds below this threshold could be encoded by the combination of the place and firing rate of stimulated hair cells. So, in general, hair cells located near the tip of the basilar membrane would signal that we’re dealing with a lower-pitched sound. However, differences in firing rates of hair cells within this location could allow for fine discrimination between low-, medium-, and high-pitch sounds within the larger low-pitch context.

## 5.5: The Other Senses

Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than of our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).

### Review Questions

#### Q1

Chemical messages often sent between two members of a species to communicate something about reproductive status are called ________.

1. hormones
2. pheromones
3. Merkel’s disks
4. Meissner’s corpuscles

#### Q2

Which taste is associated with monosodium glutamate?

1. sweet
2. bitter
3. umami
4. sour

#### Q3

________ serve as sensory receptors for temperature and pain stimuli.

1. free nerve endings
2. Pacinian corpuscles
3. Ruffini corpuscles
4. Meissner’s corpuscles

#### Q4

Which of the following is involved in maintaining balance and body posture?

1. auditory nerve
2. nociceptors
3. olfactory bulb
4. vestibular system

### Critical Thinking Question

#### Q5

Many people experience nausea while traveling in a car, plane, or boat. How might you explain this as a function of sensory interaction?

#### Q6

If you heard someone say that they would do anything not to feel the pain associated with significant injury, how would you respond given what you’ve just read?

#### Q7

Do you think women experience pain differently than men? Why do you think this is?

### Personal Application Question

#### Q8

As mentioned earlier, a food’s flavor represents an interaction of both gustatory and olfactory information. Think about the last time you were seriously congested due to a cold or the flu. What changes did you notice in the flavors of the foods that you ate during this time?

### Solution

B

C

A

D

#### S5

When traveling by car, we often have visual information that suggests that we are in motion while our vestibular sense indicates that we’re not moving (assuming we’re traveling at a relatively constant speed). Normally, these two sensory modalities provide congruent information, but the discrepancy might lead to confusion and nausea. The converse would be true when traveling by plane or boat.

#### S6

Pain serves important functions that are critical to our survival. As noxious as pain stimuli may be, the experiences of individuals who suffer from congenital insensitivity to pain makes the consequences of a lack of pain all too apparent.

#### S7

Research has shown that women and men do differ in their experience of and tolerance for pain: Women tend to handle pain better than men. Perhaps this is due to women’s labor and childbirth experience. Men tend to be stoic about their pain and do not seek help. Research also shows that gender differences in pain tolerance can vary across cultures.

## 5.6: Gestalt Principles of Perception

Gestalt psychology centers around the belief that perception involves more than simply combining sensory stimuli. The word gestalt means form or pattern, but its use reflects the idea that the whole is different from the sum of its parts. In other words, the brain creates a perception that is more than simply the sum of available sensory inputs, and it does so in predictable ways. Gestalt psychologists translated these predictable ways into principles by which we organize sensory information.

### Review Questions

#### Q1

According to the principle of ________, objects that occur close to one another tend to be grouped together.

1. similarity
2. good continuation
3. proximity
4. closure

#### Q2

Our tendency to perceive things as complete objects rather than as a series of parts is known as the principle of ________.

1. closure
2. good continuation
3. proximity
4. similarity

#### Q3

According to the law of ________, we are more likely to perceive smoothly flowing lines rather than choppy or jagged lines.

1. closure
2. good continuation
3. proximity
4. similarity

#### Q4

The main point of focus in a visual display is known as the ________.

1. closure
2. perceptual set
3. ground
4. figure

### Critical Thinking Question

#### Q5

The central tenet of Gestalt psychology is that the whole is different from the sum of its parts. What does this mean in the context of perception?

#### Q6

Take a look at the following figure. How might you influence whether people see a duck or a rabbit?

Figure 5.E.1: Duck or Rabbit?

### Personal Application Question

#### Q7

Have you ever listened to a song on the radio and sung along only to find out later that you have been singing the wrong lyrics? Once you found the correct lyrics, did your perception of the song change?

### Solution

C

A

B

D

#### S5

This means that perception cannot be understood completely simply by combining the parts. Rather, the relationship that exists among those parts (which would be established according to the principles described in this chapter) is important in organizing and interpreting sensory information into a perceptual set.

#### S6

Playing on their expectations could be used to influence what they were most likely to see. For instance, telling a story about Peter Rabbit and then presenting this image would bias perception along rabbit lines.