Sensation & Perception

Question 1

Absolute threshold

Answer 1

Smallest magnitude of stimulus that can be perceived 50% of the time. Minimum stimulus energy needed to activate the sensory system.

Question 2

Just noticeable difference

Answer 2

Proposed by Ernst Weber, aka difference threshold. The smallest difference between two stimuli that can be consistently and accurately detected on 50% of trials.

Question 3

Weber’s law

Answer 3

A mathematical model of the difference threshold stating that the magnitude needed to detect physical change in a stimulus is proportional to the absolute magnitude of that stimulus. Thus, the more intense the stimulus, the greater the change that must be made in it to be noticed.

Question 4

Signal detection theory

Answer 4

States that there is no absolute threshold. Detection depends on the intensity of the physical energy and internal factors like cost & benefits associated with the detection.

Question 5

Response bias

Answer 5

Measures how risky the subject is in sensory decision-making; based upon non-sensory factors

Question 6

Transduction

Answer 6

The translation of physical energy into neural impulses or action potential. Occurs at the receptors - cells specialised for conversion of one kind of energy.

Question 7

Subliminal perception

Answer 7

Presumed ability to perceive stimulus that is below the threshold of conscious experience

[subliminal messaging & visual priming]

Question 8

Sensory adaptation

Answer 8

Reduced sensitivity to unchanging stimulus over time

eg: feeling of tongue in the mouth, clothes rubbing against skin

Question 9

Cornea

Answer 9

Curved transparent layer through which light enters the eye

Question 10

Pupil

Answer 10

Opening in the eye through which light enters - dilates and constricts based on amount of light

Question 11

Iris

Answer 11

Coloured part of the eye, consisting of involuntary muscles that control the size of the pupil

Question 12

Lens

Answer 12

Curvature right behind the iris, to bend and focus light on the retina

Question 13

Retina

Answer 13

Complex sheet of cells and fibres at the back of the eyeball, contains rods and cones

Question 14

Fovea

Answer 14

Area in the center of the retina with the highest concentration of cones. Visual acuity highest. Used when we want to see things clearly.

Question 15

Optic nerve

Answer 15

Bundle of nerves located the back of the eye, carries visual info to the brain

Question 16

Blind spot

Answer 16

Point in the region of the retina where the optic nerve leaves and blood vessels enter and leave the retina

Question 17

Duplicity theory of vision / Duplex theory

Answer 17

The theory that vision depends on the activity of two types of receptors: rods and cones

Question 18

Rods

Answer 18

Allow perception of achromatic colours, used in levels of low light. Not involved in colour vision. 120 million.

Question 19

Cones

Answer 19

Used to see chromatic and achromatic colours. Responsible for greatest acuity and daylight vision. 6 million.

Question 20

Trichromatic theory

Answer 20

By Young & Helmhotz - A physiological basis of color vision stating that the retina has 3 types of cones sensitive to different wavelength of light [red, blue & green]

Question 21

Opponent process mechanism of vision

Answer 21

By Hering - Theory that there are 3 types of cones that have two types of colour receptors each which respond to two different wavelengths.

Blue or Yellow; Red or Green; Black or White

Question 22

Connection between receptors and optic nerve

Answer 22

Rods and cones connect with bipolar neurons that connect with ganglion cells. Ganglion cells form the optic nerve.

Ganglion cells represent a combination of rods and cones, more rods than cones, ergo cones are more sensitive to fine detail.

Question 23

Visual pathway in the brain

Answer 23

From the optic chiasm, the information goes to several different places in the brain: the lateral geniculate nucleus of the thalamus, the visual cortex in the occipital lobe, and the superior colliculus

Question 24

Optic chiasm

Answer 24

The location at the base of the brain at which the optic nerves from the two eyes meet. In humans, the nerve fibres from the nasal half of each retina cross, so that each hemisphere of the brain receives input from both eyes.

Question 25

Feature detection theory

Answer 25

Proposed by Hubel & Wiesel - certain cells in the cortex are maximally sensitive to certain features of stimuli. Simple, complex & hypercomplex cells.

Question 26

Rhodopsin

Answer 26

Photochemical made of derivative of vitamin A, retinal and protein, opsin. Present in rods.

Question 27

Simultaneous brightness contrast

Answer 27

The apparent enhanced difference in brightness resulting from simultaneous stimulation by two stimuli of differing brightness. For example, a grey disk looks darker on a white background than on a black background.

Question 28

Afterimage

Answer 28

Sensation what appears after a prolong or intense exposure to a stimulus

Question 29

Terms in depth perception

Answer 29

Monocular cues:

• relative size
• interposition [overlapped object is considered further away]
• height cues
• motion parallax [objects that are closer appear to move faster (in opposite direction) than objects that are further (in same direction)]
• linear perspective
• texture gradient [closer are grainier, farther are smoother]

Binocular cues:

• convergence [brain takes feedback from eye muscles that move inwards when seeing a closer object]
• retinal disparity [retinal points that give rise to different principal visual direction and diplopia] [its also known as stereopsis]

Question 30

Figure-ground relationship

Answer 30

Dividing the world into two parts: the discrete figure and background against which it stands out

Question 31

Gestalt laws of perception

Answer 31

Proximity - closer are grouped together
Similarity - sameness grouped together
Good continuation - point connected by a straight or curved line seen as together
Closure - figures seen as more complete than they really are
Common region - same region is seen as together

Question 32

Law of prägnanz (or good figure)

Answer 32

States that perceptual organization will always be as “good” (i.e., regular, simple, symmetrical, etc.) as possible

Question 33

Bottom-up processing

Answer 33

Process of object perception that responds directly to components of the stimulus based on features and combines the component to form a whole pattern

Question 34

Top-down processing

Answer 34

Proposed by Richard Gregory

Object perception guided by memories and expectations to recognise the whole object and then recognise components

It is constructive

Question 35

Apparent motion

Answer 35

When two or more stationary lights flicker in quick succession they are perceived as one light moving

Phi phenomenon

Question 36

Induced motion

Answer 36

Stationary light appears to be moving when background is moving

Question 37

Autokinetic effect

Answer 37

Stationary light in a completely dark room appears to be moving erratically due to no frame of reference

Question 38

Motion aftereffect

Answer 38

The perception that a stationary object or scene moves following prolonged fixation of a moving stimulus. The illusory movement is in the opposite direction to the movement of the stimulus that induced the effect.

[waterfall effect]

Question 39

Perceptual constancies

Answer 39

Tendency to perceive aspects of world as unchanging even if sensory input shifts

Question 40

Size constancy

Answer 40

Tendency for the perceived size of an object to remain constant despite variations in the size of its retinal image

Question 41

Shape constancy

Answer 41

Tendency for the perceived shape of an object to remain constant despite variations in the shape of its retinal image

Question 42

Light/brightness constancy

Answer 42

Tendency for the perceived lightness of an object to remain constant despite changes in illumination

Question 43

Colour constancy

Answer 43

Tendency for the perceived color of an object to remain constant despite changes in the spectrum of light falling on it

Question 44

Illusion

Answer 44

When perception yields false interpretation of reality

Question 45

Theory of misapplied constancy

Answer 45

When looking at illusions, we interpret certain cues as suggesting that some parts are further away than others

Question 46

Size-distance invariance

Answer 46

When estimating size of an object, we take into account the size of the image casted on the retina and apparent distance

Question 47

Cocktail party phenomenon

Answer 47

Ability to focus on a single voice in a noisy environment

Question 48

Selective attention

Answer 48

Attending to certain aspects of the environment while others are moved to the background. Maximize info from object of focus and reduce sensory interference from others.

Question 49

Perceptual learning

Answer 49

An increase in the ability to extract information from the environment as a result of experience or practice with the stimulation coming from it

Perception can be molded through learning. Eg: People who work at a certain job - ability to pick up on slightest change in stimuli compared to others. Blind people.

Question 50

Perceptual cognitive styles

Answer 50

Dimensions that determine variation in perceptual style:

• degree to which their perceptions are flexible or constricted; more flexible has wider focus of attention and less affected by interfering influences and less dominated by internal needs
• field dependence or independence; dependent people find it hard to break down what is perceived to elements and emphasize whole over parts

Question 51

Structure of the ear

Answer 51

Pinna in the outer ear picks up energy which travels through the auditory canal into the eardrum.

Oscillation of the membrane of the eardrum moves 3 small bones called ossicles. Now the vibration is carried from middle ear to cochlea in inner ear. Energy is amplified in middle ear.

Cochlea contains 3 fluid-filled canals: vestibular canal, cochlear canal, tympanic canal

The fluid in the cochlea cause hair cells to have a bending motion. This bending motion transducts mechanical energy into nerve signals. These signal go to the auditory nerve, into the brain.

Question 52

Inattentional blindness

Answer 52

Unattended stimulus doesn’t register itself in individual’s consciousness

Question 53

Human eye is capable of perceiving ____ nanometers

Answer 53

700-400

Question 54

Myopia

Answer 54

Near-sightedness

Question 55

Hyperopia

Answer 55

Far-sightedness

Question 56

Seat of light sensitive photoreceptors

Answer 56

Retina

Question 57

Human ear can hear _____ Hz

Answer 57

20-20,000

Question 58

Frequency theory by Ernest Rutherford

Answer 58

Rate of firing of auditory neurons is equal to the frequency of the sound waves

If a neuron fires at a rate of 100, the frequency is also 100 Hz.

Question 59

Place theory of pitch perception by Helmholtz

Answer 59

Specific points in the cochlea, fluid waves peak depending on the frequency of the waves which also influence the bending of the hair cells

Question 60

2 types of hearing loss

Answer 60

Nerve deafness: Damage of receptors in the inner ear or auditory nerve usually due to loud noise

Conduction deafness: Related to the problems of the mechanical systems (outer and middle ear) which are responsible for transmitting sound waves to the cochlea.

Question 61

Proprioception

Answer 61

Sense of body position

Question 62

Kinesthesis

Answer 62

Sense of movement

Question 63

Intense stimuli are received by pain receptors called _____, which are found at the ends of nerves that extend from the spinal cord to the skin.

Answer 63

Nociceptors

Question 64

Gate control theory

Answer 64

The hypothesis that the subjective experience of pain is modulated by large nerve fibers in the spinal cord that act as gates, such that pain is not the product of a simple transmission of stimulation from the skin or some internal organ to the brain. Rather, sensations from pain receptors have to pass through these spinal gates to the brain in order to emerge as pain perceptions.

The status of the gates, however, is subject to a variety of influences (e.g., drugs, injury, emotions, possibly even instructions coming from the brain itself), which can operate to shut them, thus inhibiting pain transmission, or cause them to be fully open, thus facilitating transmission.