Sensation and Perception

Question 1

What is an absolute threshold?

Answer 1

The minimum stimulus energy needed to activate a sensory system

Question 2

What is subliminal perception?

Answer 2

Perception of stimuli below a threshold; in this case, of conscious awareness (perception that occurs without conscious awareness)

Question 3

What is a difference threshold

Answer 3

How different (in magnitude) two stimuli must be before they are perceived to be different

Question 4

What is just noticeable difference?

Answer 4

Same as difference threshold (how different two stimuli must be before they are perceived to be different) but in different units (jnd)

Question 5

What is Weber’s Law?

Answer 5

What’s important in producing a jnd is not the absolute difference between the two stimuli, but the ratio of them; change needed = standard stimulus

Question 6

What is Fechner’s Law?

Answer 6

Expresses the relationship between the intensity of the sensation and the intensity of the stimulus; derived from Weber’s law; sensation increases more slowly as intensity increases (might be incorrect - replaced with Stevens’ Power Law)

Question 7

What is signal detection theory?

Answer 7

When measure thresholds in experiments, measuring what the person says she received rather than what she actually sense; other, non-sensory, factors influence what the subject says she senses; leads to response bias

Question 8

What are ROC curves?

Answer 8

Used to graphically summarize a subject’s response in signal detection experiment; refined by John A. Swets; includes: (1) Hit - signal and perception; (2) Miss - signal and no perception; (3) False alarm - no signal and perception; (4) Correct negatives - no signal and no perception

Question 9

What are the three steps that make up the processing of sensory information?

Answer 9

1. Reception
2. Transduction - translation of physical energy into neural impulses or action potentials
3. Electrochemical energy is sent to the various projection areas along neural pathways; project areas further analyze sensory input

Question 10

What is the cornea?

Answer 10

Clear, domelike window in front of you eye; gathers and focuses incoming light

Question 11

What is the pupil?

Answer 11

Hole in the iris; contracts in bright light and expands in dim light to let more light in

Question 12

What is the iris?

Answer 12

Colored part of the eye; has involuntary muscles and autonomic nerve fibers; controls the size of the pupil and therefore the amount of light in the eye

Question 13

What is the lens?

Answer 13

Lies right behind the iris; helps to control the curvature of the light coming in and can focus near or distant objects on the retina

Question 14

What is the retina?

Answer 14

In the back of the eye; screen filled with neutral elements and blood vessels; image-detecting part of the eye

Question 15

What is the duplexity or duplicity theory of vision?

Answer 15

Retina contains two kinds of photoreceptors; light passes through the intermediate sensory neurons before reaching and stimulating the photo-receptors; blind spot where the optic nerve leaves the eye

Question 16

What do cones do?

Answer 16

Cones are used for Color vision and for perceiving fine detail; most effective in bright light

Question 17

What do rods do?

Answer 17

In reduced illumination, rods function best and allow perception of achromatic colors; low sensitivity to detail; not involved in color vision

Question 18

What is the fovea?

Answer 18

The middle section of the retina; only cones; best visual acuity; most sensitive in normal daylight vision

Question 19

What is the optic chasm?

Answer 19

Fibers from nasal half of retina cross paths; from the optic chasm, the info goes to several places: (1) lateral geniculate nucleus of the thalamus; (2) visual cortex in the occipital lobe; (3) super colliculus

Question 20

What was Hubel and Wiesel’s contribution to psychology?

Answer 20

Found a neural basis for feature detection theory; suggests that certain cells are maximally sensitive to certain features of stimuli; used single-cell recording to detect microelectrode small can’t be seen with an ordinary microscope in the cortex

Question 21

What is illumination?

Answer 21

Physical, objective measurement of amount of light falling on a surface

Question 22

What is brightness?

Answer 22

Subjective impression of intensity of a light stimulus

Question 23

What is adaptation?

Answer 23

Our ability to adapt to darker spaces or lighter spaces

Question 24

What is simultaneous brightness contrast?

Answer 24

When something appears brighter when surrounded by something dark than when surrounded by something light

Question 25

What is lateral inhibition?

Answer 25

Adjacent retinal cells inhibit one another; sharpens and highlights borders between light and dark areas

Question 26

What is the Young-Helmhotz theory or Trichromatic theory of vision?

Answer 26

Retina contains three types of cones that are sensitive to different colors; colors produced by combined stimulation of these receptors - blue/green/red primary

Question 27

What is the Opponent-Process theory of color vision?

Answer 27

Suggested that four primaries: blue, green, yellow, red, were arranged in opposing pairs; red - excite red/green cell; green inhibit (can’t have reddish green); also included black-white as an opposing pair

Question 28

J. J. Gibson

Answer 28

studied texture gradients: variations in perceived surface texture as a function of the distance from the observer. As the distance increases, so does the perceived density

Question 29

Motion parallax

Answer 29

next time in car or train – look at horizon – fix gaze on object half-way between you and horizon; objects closer than fixed point appear to move in the same direction as you do

Question 30

Kinetic depth perception

Answer 30

when object moves but perceiver stays in the same place

Question 31

Binocular disparity/stereopsis

Answer 31

distance between the eyes provides us with two slightly disparate views on the world
Called binocular parallax; When combine these two, get a perception of depth; Only one that requires two eyes: binocular depth cue; all others: monocular depth cue

Question 32

Interposition

Answer 32

cue for depth perception when object A covers or overlaps with object B
• We see object A as being in front

Question 33

Relative size

Answer 33

as objects get farther away, their images on the retina get smaller

Can tell how far away something is from you relative to another by comparing the size of the images on the retina with what you know about their actual sizes

Question 34

Linear perspective

Answer 34

convergence of parallel lines in the distance

Studied by George Berkeley

Question 35

Five laws explain form perception:

Answer 35

o Proximity: close together = unit
o Similarity: similar = grouped together
o Good continuation
o Closure
o Pragnanz: perceptual organization will always be as regular, simple, and symmetrical as possible
• Subjective contours: perceiving contours/shapes that aren’t really there

Question 36

loudness

Answer 36

The amplitude or physical intensity of a sound wave largely determines loudness

Question 37

pitch

Answer 37

Frequency, the pace of vibrations or sounds waves per second for a particular sound, determines pitch. Low frequency is perceived as low pitch and vice versa. Frequency is measured in hertz (Hz), and humans best hear frequencies around 1000 Hz

Question 38

Timbre

Answer 38

Timbre comes from the complexity of the sound wave

Question 39

Outer ear

Answer 39

Outer ear consists of the parts that you see called pinna and the auditory canal. Vibrations from sound move down this canal to the middle of the ear

Question 40

Middle ear

Answer 40

Middle ear begins with tympanic membrane (also known as the eardrum), which is stretched across the auditory canal. Behind this membrane are the ossicles (three small bones), the last of which is the stapes. Sound vibrations bump against the tympanic membrane, causing the ossicles to vibrate.

Question 41

inner ear

Answer 41

The inner ear is responsible for both hearing and balance. It begins with the oval window, which is tapped upon by the stapes. These vibrations then activate the fluid-filled, snail-shell-like cochlea, which contain the ear parts for hearing (the basilar membrane and the organ of corti). The movement of the cochlear fluid activates the hair-cell receptors on the basilar membrane and the organ of corti. This movement on the basilar membrane is called the traveling wave. The vesibular sacs (which also respond to hair movement) are sensitive to tilt and provide our sense of balance.

Question 42

How does ear interpret sound?

Answer 42

Receptor cells in the inner ear activate nerve cells that change the information into an electrical message the brain can process. The auditory system that leads to the auditory cortex consists of olivary nucleus, the inferior colliculus, and the medial geniculate body.

Question 43

nativist theory

Answer 43

perception and cognition are largely innate

Question 44

structuralist theory

Answer 44

asserts that the perception is the sum total of sensory input. The world in understood through bottom-up processing.

Question 45

gestalt theory

Answer 45

asserts that people tend to see the world as comprised of organized wholes.

Question 46

James Gibson

Answer 46

perceptual development is the increasing ability of a child to make finer discriminations among stimuli. The optic array, or all of the things a person sees, trains people to perceive.

Question 47

reception

Answer 47

takes place when receptors for a particular sense detect a stimulus. The receptive field is the part of the world that triggers a particular neuron.

Question 48

sensory transduction

Answer 48

process in which physical sensation is changed into electrical messages that the brain can understand. Sensory transduction is the heart of the senses.