Sensation & Perception Flashcards Preview

MCAT Behavioural Sciences > Sensation & Perception > Flashcards

Flashcards in Sensation & Perception Deck (111):
1

Sensation def.

Can be considered transduction - the conversion of physical, electromagnetic, auditory, and other information to electrical signals in the nervous system

performed by receptors in the PNS

2

Perception def.

Processing of sensory information to make sense of its significance

3

Sensory receptors

Neurons that respond to stimuli and trigger electrical signals
-can encode multiple aspects of a stimulus

4

Ganglia

collections of neuron cell bodies found outside the CNS
-used to transmit information from the receptors to the CNS

5

Photoreceptors

respond to electromagnetic waves in the visible light spectrum

6

hair cells

respond to movement of fluid in the inner ear structures
-hearing, rotational and linear acceleration

7

nociceptors

respond to painful or noxious stimuli (somatosensation)

8

thermoreceptors

respond to changes in temperature

9

osmoreceptors

respond to the osmolarity of the blood

10

olfactory receptors

respond to volatile compounds

11

taste receptors

respond to dissolved compounds

12

Threshold

minimum amount of a stimulus required to render a change in perception

13

Absolute threshold

minimum stimulus energy needed to activate a sensory system
-threshold in sensation not perception
-how bright/loud/intense a stimulus must be before we sense it

14

Threshold of conscious perception

sensory signals can reach the CNS without perception occurring
-stimulus is to subtle or brief to be attended to

15

Difference threshold

also called the just-noticeable threshold

minimum difference in magnitude between two stimuli before one can perceive this difference

16

Weber's law

Constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus

= change in stimulus / original stimulus magnitude

17

signal detection theory

How the perception of stimuli can be affected by nonsensory factors such as memory, motives and expectation

18

Response bias

tendency of subjects to respond systematically to a stimulus in a certain way due to nonsensory factors
-can be determined by the proportion of misses or false alarms in an experiment

19

Basic signal detection experiment components

catch trial: signal is presented

noise trial: signal is not presented

hits: correct perception of signal

misses: fails to perceive given signal

false alarms: perceives signal when none was given

correct negatives: correct identification of no signal

20

The eye detects light in the form of _____

photons

21

Sclera

"white" of the eye
-thick structural layer
-does not cover the front most part of the eye

22

Two sets of vessels supplying the eye

1. choroidal vessels (b/w retina and sclera)
2. retinal vessels

23

Retina - form & function

innermost layer of the eye
-consists of neural elements and blood vessels
-develops as an outgrowth of brain tissue (part of CNS)

function: convert incoming photons of light into electrical signals

24

Cornea

clear, domelike window in the front of the eye
-gathers and focuses incoming light

25

Anterior chamber

Part that is in front of the iris

26

Posterior chamber

between the iris and the lens
-where aqueous humor is made by the ciliary body

27

Iris

Coloured part of the eye
-dilator pupillae: opens the pupil under sympathetic stimulation
-constrictor pupillae : constricts the pupil under parasympathetic stimulation

28

choroid

middle layer of the eye
-continuous with the iris as well as the ciliary body

29

Ciliary body

produces aqueous humor that bathes the front part of the eye

30

Canal of Schlemm

drains the aqueous humor

31

Lens

Helps control the refraction of incoming light
-located behind the iris
-shape is changed by contraction of the ciliary muscle which is under parasympathetic control

32

Accomodation

Process in which the ciliary muscle contracts, pulling on the suspensory ligaments which changes the shape of the lens

33

Vitreous

transparent gel that supports the retina

34

Duplexity/Duplicity theory of vision

retina contains two different kinds of photoreceptors (rods and cones)

35

Rods

-Work best in reduced lighting
-Only allow for sensation of light or dark as they only contain one pigment: rhodopsin
-low sensitivity to detail

*~120 million rods in the retina

36

Cones

-Work best in bright light (different cones absorb different wavelengths of light: short, medium, long)
-Used for colour vision
-High sensitivity to detail

37

Macula

central section of the retina with a high concentration of cones

38

Fovea

centermost point of the macula, contains ONLY cones
-visual acuity is best at the fovea

39

Blind spot

where the optic nerve leaves the eye
-no photoreceptors present

40

Bipolar cells

connect with rods and cones

synapse with ganglion cells

41

Ganglion cells

connect with bipolar cells
group together to form the optic nerve

*each one represents the combined activity of many rods and cones
-this results in a loss of detail as info from photoreceptors is combined

42

Amacrine and Horizontal cells

Receive input from multiple retinal cells in the same area before the info is passed to ganglion cells
-accentuate slight differences between visual information in each bipolar cell
-increase perception of contrasts

43

Visual pathways

both the physical connections between the eyes and the brain AND the flow of visual information along these connections

44

Optic chiasm

Where the fibers from the nasal half of each retina cross paths
-fibres carry information form the temporal visual field from each eye
*temporal fibres (carrying the information from the nasal visual field) do not cross the chiasma

==> because of this, all information from the left visual field of each eye projects to the right side of the brain and visa versa

45

Optic tracts

reorganized pathways leaving the optic chiasm
-travel to:
the lateral geniculate nucleus
Visual cortex (occipital lobe) via radiation in the temporal and parietal lobes

46

Lateral geniculate nucleus (LGN)

Located in the thalamus

47

Parallel processing

ability to simultaneously analyze and combine information regarding colour, shape, and motion
-then compare images to memories to determined what is being viewed

48

Parvocellular cells

Detect shape in the visual pathway
-have very high colour spatial resolution
-permit fine detail when an object is stationary
-poor temporal resolution = not for moving objects

49

Magnocellular cells

Detect motion in the visual pathway
-high temporal resolution
-low spatial resolution
*provide a blurry but moving image of the object

50

Vestibular Sense

rotational and linear acceleration

51

Pinna/Auricle

cartilaginous outer part of the ear
-first part of the ear that the sound passes through
-function is to channel sounds waves into the external auditory canal

52

External auditory canal

Canal of the outer ear
-directs sound waves to the tympanic membrane

53

Tympanic membrane

Vibrates in phase with the incoming sound waves
-frequency of the sound waves determines the rate at which the tympanic membrane vibrates (high frequency = high vibration)
-Louder sounds have greater intensity and therefor greater amplitude of vibration

*Divides the middle ear and the outer ear

54

Ossicles

three smallest bones in the body
-found in the middle ear
-malleus, incus, staples

55

Order of ossicle action

1. Malleus acts on the => 2. Incus acts on the => 3. Stapes => presses on the oval window of the cochlea

56

Eustachian tube

Connects the middle ear to the nasal cavity
-helps equalize pressure between the middle ear and the environment

57

Inner ear

Located in a bony labyrinth
-contains the cochlea, vestibule and the semicircular canals
-structures are continuous with each other and filled by the membranous labyrinth which in turn is filled with a K+ rich fluid called endolymph

58

Endolymph

Potassium rich fluid that fills the membranous labyrinth

59

Cochlea: structure & function

Spiral shaped organ divided into 3 parts called scalae
-middle scalae houses the organ of Corti (resting on the basilar membrane)
-tectorial membrane (immobile) rests on top of the organ of Corti

60

Organ of Corti

comprised of thousands of hair cells that are bathed in endolymph

61

Perilymph

Transmits vibrations from the outside world and cushions the inner ear structures
-fills the other 2 scalae of the cochlea

62

Round window

Membrane covered role in the cochlea (lower down than the oval window) that allows the perilymph in the outer scalae to move

63

Basilar membrane movements

Sound entering the cochlea via the oval window causes vibrations in the perilymph which are transmitted to the basilar membrane

64

Which nerve carries stimulus to the CNS?

Auditory (vesibulocochlerar) nerve

65

Vestibule

Portion of the bony labyrinth that contains the utricle and the saccule
-sensitive to linear acceleration
-used as part of balancing apparatus
-determining orientation in 3D space

66

Hair cells of the utricle and saccule

Covered with otoliths
-as the body accelerates the otoliths resist the motion, causing the hair to bend
-the hair cells are then stimulated and send a message to the brain

67

Semicircular Canals

3 semicircular canals are sensitive to rotational acceleration
-arranged perpendicular to each other
-each end in a swelling called the ampula where the hair cells are located

*when the head rotates, endolymph resists this motion and cause the hairs to bend, sending signals to the brain

68

Auditory pathways (order)

1. Most signals pass through the vestibularcochlear nerve to the brainstem
2. Then it ascends to the medial geniculate nucleus of the thalamus
3. Projects to the auditory cortex in the temporal lobe for sound processing
** some info also sent to superior olive (localization) and the inferior colliculus (startle response)

69

Vestibulo-ocular reflex

Keeping the eyes fixed on a point which the head is turning
-startle response
-involves the inferior colliculus

70

Hair cell structure

Have long tufts of stereocilia on surface

71

Hair cell function

1. Vibrations on the basilar membrane causes movement of endolymph and stereocilia to sway
2. Swaying causes the opening of ion channels
3. A receptor potential is created

72

Hair cells + tectorial membrane

Hair cells directly connected to the tectorial membrane are involved in amplifying incoming sounds

73

Tonotopical organization of cochlea

Basilar membrane thickness changes throughout the cochlea
-closest to oval window = highest frequency pitches
-furthest from oval window = lowest frequency pitches

74

Only 1 of the senses that does not pass via the thalamus

Smell

75

Smell is considered a ____ sense

Chemical sense
-responds to volatile or aerosolized chemicals

76

Olfactory chemoreceptors (nerves)

Located in the olfactory epithelium in the upper part of the nasal cavity
-highly varied
-chemicals must bind to specific receptors

77

Pheromones

Secreted by one person or animals and bind to the chemoreceptors of another, urging them to behave in a certain way

78

Olfactory pathway

1. Odor molecules are inhaled into the nasal passages
2. contact the olfactory nerves
3. olfactory receptors are activated and they send signals to the olfactory bulb
4. Signals are then relayed via the olfactory tract to higher regions of the brain (ie. limbic system)

79

5 basic tastes

Sweet, sour, bitter, salty, and umami (savoury)

80

Flavour

Complex interplay between smell and taste
-can be affected by non-chemical stimuli

81

Taste chemoreceptors

sensitive to dissolved chemicals

82

Taste buds

groups of cells that are receptors for taste

83

Papillae

small bumps on the tongue which contain the taste buds

84

Taste pathway

1. Info travels from taste buds to the brainstem
2. Ascends to the taste centre in the thalamus
3. Travels from the thalamus to higher order brain regions

85

4 modalities of Somatosensation

1. Pressure
2. Vibration
3. Pain
4. Temperature

86

Brown-Séquard syndrome

If half the spinal cord is severed the patient loses pain and temperature sensation on the opposite side of the lesion and pressure/vibration sensation on the same side

*pain + temp use a different pathway then pressure +vibration

87

Pacinian corpuscules

respond to deep pressure and vibration

88

Meissner corpuscules

respond to light touch

89

Merkle cells (discs)

respond to deep pressure and texture

90

Ruffini endings

respond to stretch

91

Free nerve endings

respond to pain and temperature

92

Somatosensory signal destination

Somatosensory cortex in parietal lobe

93

Two point thresholds

minimum distance necessary between two points of stimulation on the skin such that the points will be felt as distinct

94

Physiological zero

Normal temperature of the skin
-objects feel cold if they are below and hot if they are above

95

Nociceptors

Involved in pain perception (most common receptor)

96

Gate theory of Pain

Special gating mechanism present that can turn pain signals on and off

Spinal cord can preferentially forward signals from other touch modalities, therefore reducing the pain sensation

97

Kinesthetic sense

Also known and proprioception
= ability to tell where one's body is in space

98

Location of proprioception receptors

Mainly muscles and joints

99

Bottom up processing

object recognition by parallel processing and feature detection
-combining stimuli into a cohesive image before determining what the object is

*also called data-drive processing*

100

Top down processing

Driven by memories and expectation which allow the brain to recognize the whole object, then to recognize its components based on these expectations
-allow for quicker recognition

101

Perceptual organization

Ability to use both top down and bottom up processing in tandem with other sensory clues about an object to create a complete picture

102

Depth perception

monocular clues: relative size of the object, partial obscuring, convergence of parallel lines at a distance, position of object in visual field, and lights/shadows

binocular clues: slight differences in images projected on the 2 retinas and the angle required between the eyes to bring an object into focus

103

Form of an object

determined via parallel processing and feature detection

104

Constancy

idea that we can perceive certain characteristics of objects to remain the same, despite changes in the environment

105

Gestalt principles

ways for the brain to infer missing parts of a picture when it is incomplete

106

Law of proximity

elements close together tend to be perceived as a unit

107

Law of similarity

objects that are similar tend to be grouped together

108

Law of good continuation

elements that appear to follow the same pathway tend to be grouped together
-perceive continuous patterns over abrupt changes

109

Subjective contours

perceive contours and therefore shapes that are not actually present

110

Law of closure

A space that is surrounded by a contour it tends to perceived as a complete figure
-certain figures tend to be perceived as more complete than they actually are

111

Law of prägnanz

perceptual organization will always be as regular, simple, and symmetric as possible
-governs the other gestalt principles