Sensation & Perception

Question 1

Define Sensation

Answer 1

the conversion of physical, electromagnetic, auditory and other information from the internal and external environment into electrical signals in the ns

Question 2

Define Perception

Answer 2

processing of sensory information to make sense of its significance

Question 3

What are sensory receptors?

Answer 3

nerves that respond to stimuli and trigger electrical signals

Question 4

What are sensory ganglia?

Answer 4

• collections of cell bodies outside the CNS

- associated with sensory receptors

Question 5

What is sensory stimuli transmitted through?

Answer 5

projection areas in the brain that further analyze sensory input

Question 6

Define threshold

Answer 6

minimum amount of stimulus required to cause a change in signal transduction

Question 7

Define absolute threshold

Answer 7

minimum amount of stimulus energy needed to activate a sensory system

Question 8

What is the threshold of conscious perception?

Answer 8

minimum amount of stimulus energy that will create a signal large enough in size and long enough in duration to be brought into awareness

Question 9

What is the difference threshold (just-noticeable difference)?

Answer 9

• minimum difference in magnitude between two stimuli that can be detected half the time
• the smallest difference that is sufficient for a change in a stimulus to be perceived
• the more sensitive the sensory system, the smaller the threshold

Question 10

What does Weber’s Law state?

Answer 10

• the just-noticeable difference for a stimulus is proportional to the magnitude of the stimulus and this proportion is constant over most of the range of possible stimuli
• the change in a stimulus required to meet the difference threshold is a certain fraction of the originally presented stimulus
• the fraction is constant for each sense but differs based on the original stimulus and what sense we are using
• predicts a linear relationship between incremental threshold and background intensity – plotting I against delta I is constant

Question 11

What is subliminal perception?

Answer 11

the perception of a stimulus below a given threshold

Question 12

Signal Detection Theory

Answer 12

• the effects of nonsensory factors (experiences, motives, expectations) on perceptions of stimuli
• the ability to detect a meaningful stimulus in the midst of vast amounts of sensory info increases an organism’s chances of survival
• there is always some amount of error in the process of distinguishing signal from noise, but a higher hit rate will increase sensitivity by the organism

Question 13

Response Bias

Answer 13

• tendency of subjects to systemically respond to a stimulus in a particular way due to nonsensory factors
• ex. person answers survey questions untruthfully b/c they feel pressure to give answers that are socially acceptable

Question 14

Adaptation

Answer 14

• decrease in response to a stimulus over time
• leads to a rise in the difference threshold for a sensory response – difference in stimulus required to evoke a response must be larger

Question 15

What is the pathway of a stimulus that reaches conscious perception?

Answer 15

sensory receptor -> afferent neuron -> sensory ganglion -> spinal cord -> brain (projection areas)

Question 16

List sensory receptors and their function (5)

Answer 16

• hair cell: sense motion of fluid in inner ear
• nociceptor: sense painful physical stimuli
• olfactory: sense volatile chemicals
• osmoreceptor: sense changes in blood concentration
• photoreceptor: sense electromagnetic radiation in the visible range

Question 17

Weber’s Law Equation

Answer 17

K = delta I / I
I =intensity of stimulus
delta I = just noticeable difference

Question 18

Object Recognition Processes – Bottom-Up Processing

Answer 18

• object recognition by parallel processing and feature detection
• brain takes individual sensory stimuli and combines them together to create a cohesive image before deterring what the object is

Question 19

Object Recognition Processes – Top-Down Processing

Answer 19

• driven by memories and expectations that allow the brain to recognize the whole object and then recognize the components based on these expectations
• allows us to quickly recognize objects without needing to analyze their specific parts

Question 20

What idea do Gestalt Principles follow?

Answer 20

the idea that the principles provide ways for the brain to infer missing parts of a picture when it is incomplete

Question 21

Law of Proximity

Answer 21

• Gestalt principle

- elements close to one another tend to be perceived as a unit

Question 22

Law of Similiarity

Answer 22

• Gestalt principle

- objects that are similar tend to be grouped together`

Question 23

Law of Good Continuation

Answer 23

• Gestalt principle
• elements that appear to follow in the same pathway tend to be grouped together
• tendency to perceive continuous patterns in stimuli rather than abrupt changes

Question 24

Subjective Contours

Answer 24

• Gestalt principle

- perceiving contours/shapes that are not actually present in the stimulus

Question 25

Law of Closure

Answer 25

• Gestalt principle
• space enclosed by a contour tends to be perceived as a complete figure
• such figures tend to be perceived as more complete/closed than they really are

Question 26

Pragnanz

Answer 26

reality/perception is often organized reduced to its simplest form possible (regular, simple, symmetric)