Sensation and Perception

Question 1

Define sensation.

Answer 1

Sensation is the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

Question 2

Define perception.

Answer 2

Perception is the process of organizing and interpreting sensory information, which enables us to recognize meaningful objects and events.

Question 3

What is bottom-up (data-driven) processing?

Answer 3

Bottom-up processing refers to processing that begins with incoming sensory information and continues upward to the brain where it is perceived, interpreted, and stored.

Question 4

What is top-down (concept-driven) processing?

Answer 4

Top-down processing refers to processing that begins with the brain’s use of preexisting knowledge and expectations to interpret incoming sensory information.

Question 5

How do bottom-up and top-down processing help explain the integration of sensation and perception?

Answer 5

Bottom-up and top-down processing help explain how sensation and perception are integrated. Bottom-up processing deals with the incoming sensory information, while top-down processing involves the brain’s existing knowledge and expectations in interpreting that sensory information.

Question 6

What are the physical stimuli for vision?

Answer 6

The physical stimuli for vision are light waves that are absorbed by photoreceptors (light-sensitive receptors) in the retina.

Question 7

What are the two types of photoreceptors?

Answer 7

The two types of photoreceptors are cones and rods.

Question 8

What are the functions of the cones?

Answer 8

The cones work best in bright light and are responsible for visual acuity (sharpness and precise detail) and the perception of color.

Question 9

What are the functions of the rods?

Answer 9

The rods do not perceive color but are most important for peripheral vision and, because they’re more sensitive to light, are responsible for vision in dim light

Question 10

What are the main theories of color vision?

Answer 10

The main theories of color vision are trichromatic theory and opponent process theory.

Question 11

What does trichromatic theory propose?

Answer 11

According to trichromatic theory, the retina contains three types of color receptors (cones) – red, blue, and green. Trichromatic theory applies to the initial level of processing in the retina.

Question 12

What does opponent-process theory propose?

Answer 12

Opponent-process theory proposes that there are three types of opponent-process cells – red/green, blue/yellow, and white/black. It applies to processing beyond the retina and explains the phenomenon of afterimages and red/green and blue/yellow colorblindness.

Question 13

What phenomenon does opponent-process theory explain?

Answer 13

Opponent-process theory explains the phenomenon of afterimages and red/green and blue/yellow colorblindness.

Question 14

What is the most frequent type of color blindness?

Answer 14

Red-green color blindness is the most frequent type.

Question 15

What are the causes of red-green color blindness?

Answer 15

Red-green color blindness is most often due to a genetic mutation but can also be the result of injury or disease (e.g., diabetes, multiple sclerosis).

Question 16

What is the genetic cause of red-green color blindness in males?

Answer 16

The genetic form of red-green color blindness in males is caused by a recessive gene on the X chromosome. Males have only one X chromosome, so inheriting the single mutated gene is sufficient to cause color blindness.

Question 17

How do females inherit red-green color blindness?

Answer 17

Females have two X chromosomes, so they are color blind only when they inherit the mutated gene from both parents.

Question 18

How does the inheritance pattern of blue-yellow color blindness differ from red-green color blindness?

Answer 18

In contrast to red-green color blindness, blue-yellow color blindness is caused by an autosomal (non-sex) dominant gene and, consequently, affects males and females equally.

Question 19

What cues contribute to the ability to perceive depth?

Answer 19

The ability to perceive depth depends on a combination of binocular cues (requiring both eyes) and monocular cues (requiring only one eye).

Question 20

What are binocular cues and when are they responsible for depth perception?

Answer 20

Binocular cues depend on both eyes and are responsible for depth perception of objects that are relatively close. They include retinal disparity and convergence.

Question 21

What is retinal disparity?

Answer 21

Retinal disparity occurs because our two eyes see objects from two different views and, the closer an object, the greater the disparity.

Question 22

What is convergence?

Answer 22

Convergence refers to the tendency of the eyes to turn inward as an object gets closer and vice versa

Question 23

What are monocular cues and when are they responsible for depth perception?

Answer 23

Monocular cues depend on one eye and are responsible for depth perception of objects at greater distances. They include the relative size of objects, the overlap (interposition) of objects, linear perspective, texture gradients, and the relative motion of objects (motion parallax).

Question 24

What types of stimuli can cause pain?

Answer 24

Pain is caused by several types of stimuli including extreme temperatures, mechanical pressure, and electrical stimulation.

Question 25

What factors moderate the perception of pain?

Answer 25

The perception of pain is moderated by several factors including current emotional state and past experience with pain.

Question 26

What is gate control theory?

Answer 26

Gate control theory is a major theory of pain perception. It distinguishes between two types of nerve fibers in the spinal cord: small unmyelinated fibers that transmit most pain signals to the brain, and larger myelinated fibers that transmit other sensory signals.

Question 27

How does gate control theory explain the transmission of pain signals?

Answer 27

According to gate control theory, whether or not pain is transmitted by small fibers depends on a “gate” that is normally opened by incoming pain signals but is closed by the transmission of other sensory signals in the large fibers and by transmission of information from the brain.

Question 28

What is synesthesia?

Answer 28

Synesthesia is a condition in which sensations in one sensory modality spontaneously trigger an associated sensation in another modality.

Question 29

What is the most common type of synesthesia?

Answer 29

The most common type of synesthesia is grapheme-color synesthesia, in which numbers or letters are associated with specific colors.

Question 30

What is a possible cause of synesthesia?

Answer 30

Synesthesia seems to have a genetic component, and there’s evidence that it’s due to increased cross-activation and cross-connectivity between the brain’s sensory areas.

Question 31

What is psychophysics the study of?

Answer 31

Psychophysics is the study of the relationship between the magnitude of physical stimuli and psychological sensations.

Question 32

What laws and theories explain the relationship between physical stimuli and psychological sensations?

Answer 32

Explanations for this relationship are provided by Weber’s law, Fechner’s law, Stevens’s power law, and signal detection theory.

Question 33

What does Weber’s law state?

Answer 33

Weber’s law states that the just noticeable difference in stimulus intensity is a constant proportion of the original stimulus value.

Question 34

What does Fechner’s law state?

Answer 34

Fechner’s law states that the subjective sensation is proportional to the logarithm of the stimulus intensity.

Question 35

What does Stevens’s power law state?

Answer 35

Stevens’s power law states that the perceived magnitude of a stimulus is proportional to a power function of the stimulus intensity.

Question 36

What does signal detection theory explain?

Answer 36

Signal detection theory explains how and why people decide if a faint stimulus is present or not by examining the interaction between sensory and cognitive processes.

Question 37

What does Weber’s law state about the just noticeable difference (JND) for a stimulus?

Answer 37

Weber’s law predicts that the just noticeable difference (JND) for a stimulus is a constant proportion, regardless of the intensity of the original stimulus.

Question 38

Give an example of how Weber’s law applies.

Answer 38

For weight, the proportion for the JND is always 2%, which means that to notice a change in weight, a second object must be at least 2% lighter or heavier than the first object.

Question 39

What are the limitations of Weber’s law?

Answer 39

Weber’s law applies only to some stimuli and to intensities in the mid-range.

Question 40

How does Fechner’s law differ from Weber’s law in its applicability?

Answer 40

Like Weber’s law, Fechner’s law works for only some stimuli; however, it’s more accurate than Weber’s law for stimuli at extreme intensities.

Question 40

What does Fechner’s law state about the relationship between psychological sensation and stimulus magnitude?

Answer 40

Fechner’s law predicts that there’s a logarithmic relationship between psychological sensation and the magnitude of a physical stimulus.

Question 41

What does Stevens’s power law propose?

Answer 41

Stevens’s power law proposes that there’s an exponential relationship between psychological sensation and the magnitude of a physical stimulus, and that the exponent varies for different stimuli.

Question 42

How did Stevens derive his power law?

Answer 42

Stevens based his law on research using the method of magnitude estimation, which required participants to assign numbers to stimuli based on the sensations they elicited.

Question 43

How does Stevens’s power law differ from Weber’s and Fechner’s laws?

Answer 43

Stevens’s power law is more accurate than Weber’s and Fechner’s laws, and it proposes that the relationship between physical stimuli and psychological sensation differs for different stimuli.

Question 44

What is signal detection theory (SDT) and how does it differ from other psychophysical laws?

Answer 44

Signal detection theory (SDT) assumes that perception of a stimulus is the outcome of both sensory and decision-making processes. In contrast to other psychophysical laws, SDT accounts for the role of uncertainty and decision factors in perception.

Question 45

What factors does SDT propose affect the decision-making process in perceiving stimuli?

Answer 45

SDT proposes that the decision-making process is accompanied by some degree of uncertainty caused by background noise, and is affected by the perceiver’s sensitivity and decision criterion.

Question 46

What is sensitivity in SDT?

Answer 46

Sensitivity is the perceiver’s ability to distinguish between the stimulus and noise.

Question 47

What is the decision criterion in SDT?

Answer 47

The decision criterion, also called decision bias or response bias, refers to the perceiver’s willingness or tendency to say that a stimulus is present in ambiguous situations.

Question 48

How do sensitivity and decision criterion affect perceptual accuracy according to SDT?

Answer 48

Greater sensitivity increases the potential for accurately perceiving a stimulus, but accuracy is also affected by the person’s decision criterion. People with the same sensitivity may make different decisions about weak stimuli if they differ in decision criterion.

Question 49

What are the four possible decision outcomes in a typical SDT experiment?

Answer 49

The four possible outcomes are: (a) hit (stimulus present, person says present), (b) false alarm (stimulus absent, person says present), (c) miss (stimulus present, person says absent), (d) correct rejection (stimulus absent, person says absent).

Question 50

What measures are derived from SDT experiment data?

Answer 50

SDT experiment data can be used to obtain an estimate of sensitivity (d-prime) and to construct a receiver operating characteristic (ROC) curve showing how decision criterion affects hit and false alarm rates at different sensitivity levels.