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Answers and Explanations

1. C—Hair cells of the cochlea transduce the mechanical energy of sound waves to the electrochemical energy of neural impulses. Rods and cones of the retina transduce light energy; cells of the olfactory epithelium and taste buds transduce chemical energy.

2. D—The curved transparent cornea and curved lens both bend light rays focusing an image on the retina.

3. A—Supertasters are especially sensitive to the sensation of bitterness that they dislike intensively and that is characteristic of many poisons. Tasters and nontasters are less sensitive to bitter substances and could die from eating them.

4. C—Light passes through mainly transparent structures. The iris and sclera are not transparent.

5. D—Smell is our most direct sense. Neurons from the olfactory mucosa synapse with neurons in the olfactory bulbs of the brain.

6. C—Peppery is sensed by pain and temperature receptors and is not a basic taste. Other than sweet, salty, bitter, and sour; umami is considered a basic taste by some psychologists.

7. B—Receptors for your sense of body position are located primarily in joints and tendons. Receptors for your vestibular sense or sense of balance are located in the semicircular canals of the inner ear.

8. B—According to Weber’s Law, the jnd is proportional to the intensity of the stimulus. So if the strength of the stimulus is doubled, the strength of the change in the stimulus that is just noticed must be doubled also.

9. B—Conventional hearing aids are primarily amplifiers. Facial bones other than the ossicles can transmit vibrations to the cochlea when vibrations are intense. Choice “C” describes cochlear implants.

10. E—According to gate-control theory you experience pain when pain messages can pass through the spinal cord via small nerve fibers (open gate) that carry pain signals.

11. B—Your sense of smell or olfaction is not important for helping you to maintain your balance. To see that vision is important, stand on one foot with your eyes closed.

12. A—In this case there is a conflict between audition signals and visual signals. When you perceive a conflict between senses, you tend to perceive what your vision tells you—visual capture.

13. E—The Gestalt organizing principle of proximity explains that you perceive objects that are close together as parts of the same group.

14. D—Retinal disparity is a binocular cue to depth. Since the picture is two dimensional, the mountains aren’t actually any farther away from your eyes than the boats, so retinal disparity will not provide information that the mountains are further away that monocular cues will offer.

15. C—Precognition is the extrasensory perception of future events, which has not been scientifically substantiated.

Rapid Review

Sensation—the process by which you detect physical energy from your environment and encode it as neural signals.

Psychophysics—the study of the relationship between physical energy and psychological experiences.

Stimulus—a change in the environment that can be detected by sensory receptors.

Absolute threshold—the weakest level of a stimulus that can be correctly detected at least half the time.

Signal detection theory—maintains that minimum threshold varies with fatigue, attention, expectations, motivation, emotional distress, and from one person to another.

Difference threshold—minimum difference between any two stimuli that a person can detect 50% of the time.

Just noticeable difference (jnd)—experience of the difference threshold.

Weber’s law—difference thresholds increase in proportion to the size of the stimulus.

Subliminal stimulation—receiving messages below one’s absolute threshold for conscious awareness.

Transduction—transformation of stimulus energy to the electrochemical energy of neural impulses.

Perception—the process of selecting, organizing, and interpreting sensations, enabling you to recognize meaningful objects and events.

Vision and the human eye:

Rays of light from an object pass from the object through your cornea, aqueous humor, pupil, lens, and vitreous humor