week6 sensation and perception

Question 1

define sensation

Answer 1

awareness resulting from the stimulation of a sense organ. Describes physical effects on our nervous system.

Question 2

define perception

Answer 2

the organization and interpretation of sensations.Describes the psychological effect of sensations upon us.

Question 3

Who were the first psychophysicists to measure how sensitive we are to various stimuli?ie how much is required for us to reliably detect it.

Answer 3

Weber and Fechner

Question 4

What is the Absolute Threshold?

Answer 4

The intensity of a stimulus which allows an organism to barely detect it 50% of the time.Our individual thresholds are different and change with time and context.

Question 5

What is a subliminal stimuli?

Answer 5

Stimulus below level of Absolute Threshold.

Question 6

Describe Weber-Fechner’s Law

Answer 6

The Difference Threshold is a constant proportion of the baseline against which the comparison is being made,
(change in intensity) divided by (baseline intensity or Ï”) = a constant. eg If k=0.2=20%, then if have 100 dots (I=100), need 120 dots to notice the difference reliably.

Question 7

What is the Signal Detection Theory?

Answer 7

Splits a person’s performance in detecting Absolute Thresholds into a) sensory sensitivity (precision)(how good sense organs are)
and b) cognitive response bias.(confidence/motivation)

Question 8

What makes us intelligent perceivers?

Answer 8

Combination of sensation and decision making.

Question 9

What is Sensory Transduction?

Answer 9

Pysical energy converted into electrochemical activity. carried out by sensory receptors.

Question 10

Describe simple sensory receptors

Answer 10

Neural cell with dendrites exposed to environment. Especially for touch,pain, pressure. Rubbing eg alters their environment, therefore they produce a neural impulse (electrochemical event)

Question 11

Describe Encapsulated sensory receptors

Answer 11

Dendritic nerve endings covered by a tissue layer which enhances stimulus detection or decreases irrelevant ones. eg Pacinian Corpuscles of the skin, respond to vibration.

Question 12

Describe Complex receptor types

Answer 12

Dendrites fundamentally modified. Key components of specialised sensory organs.

Question 13

List the special senses

Answer 13

vision, hearing,smell,taste,balance. Touch and pain to a far lesser extent.

Question 14

The wavelength of light determines?

Answer 14

Perceived colour

Question 15

The amplitude of light determines

Answer 15

Perceived intensity, or energy level.

Question 16

2 types of photoreceptors in the eye are?

Answer 16

Rods and cones

Question 17

describe cones

Answer 17

3 types, each most sensitive to either blue, green or red.Packed densely on retina esp centrally, therefore high resolution.

Question 18

What do rods detect?

Answer 18

Rods detect light at low levels (scotopic vision). low spatial acuity. They are at the periphery of the retina.

Question 19

Describe Retinal Ganglion Cells.

Answer 19

The neural activity of rods and cones influences other neurons. the overall effect of this is to influence the retinal ganglion cells. Their axons carry visual info via optic nerve to brain.

Question 20

How do neurons of the visual cortex respond?

Answer 20

Receive and integrate various inputs. Respond selectively either to patterns of light and dark, or, to directions of movement. Therefore known as “Feature detector neurons

Question 21

“What is myopia

Answer 21

near sighted. see near objects well. Either cornea or lens is too strong, or eyeball too large.

Question 22

What is Hyperopia?

Answer 22

Far sighted. Cornea/lens too weak or eyeball too small.

Question 23

What is presbyopia?

Answer 23

Lens has lost its refractive ability. Unable to see near objects. Affects everyone as they age.

Question 24

What is the most common form of colour blindness?

Answer 24

deficiency in red or green cones. affects 1 in 50, more often men. Deuteranomia is inability to see green, and is the most common type.

Question 25

What is the Trichomacy Theory?

Answer 25

The colour we perceive depends on relative activity of 3 cone types. 16 million colours possible.

Question 26

What is the Opponent-Process Theory?

Answer 26

colour we perceive depends on relative activity of 3 pairings of colour sensitive neurons, where 1 of pair inhibits other in pair.Pairings are red/green, blue/yellow (yellow is combination of red and green) and black/ white.This theory explains after-images.

Question 27

What is Gestalt Psychology?

Answer 27

Looks at mind and behaviour as a whole.In terms of visual principles, states that we tend to: 1) group features into figure versus ground object 2) group similar features into coherent objects 3) group close features into coherent objects 4) group features favouring continuity of an object 5) fill in apparant gaps to complete objects

Question 28

Binocular cues?

Answer 28

utilize and compare between the 2 eyes

Question 29

Convergence?

Answer 29

extent to which our eyes need to "cross"in order to focus. A cue for the distance of the object

Question 30

Binocular disparity?

Answer 30

(retinal disparity or stereopsis). Comparison of visual info b/n eyes. Most sensitive type of depth info. Closer objects diverge on retinas and further ones converge.depth detectors

Question 31

Explain the perception of motion.

Answer 31

Happens without cognitive intervention. Some neurons are motion detectors.

Question 32

Beta effect?

Answer 32

Show series in still images, with slight location changes, in quick succession. Therefore perceive fluid movement. eg. movie reel.

Question 33

Phi phenomenon?

Answer 33

2 seperate images flickered on and off in alteration.. Perceive fluid movement.

Question 34

Describe soundwaves

Answer 34

vibrational energy. sinewave function. time on x xis and pressure (positive =compression and negative =expansion)y axis. Amplitude =loudness or intensity of sound, decibels. Frequency=tone or pitch, hertz. We can hear between 20-20000hertz.

Question 35

describe hearing

Answer 35

1. Sound wave focused via pinna into ear canal. 2. ear drum vibrates. 3. audiory ossicles amplify vibrations 4. oval window of cochlea vibrates 5. basilar and tectorial mebranes move 6. Mechanoreceptors (hair cells) sitting on basilar membrane, with their cillia embedded in tectorial membrane,transduce vibrational energy into electrical. 7. Hair cell axons form Auditory nerve, impulse to brain.

Question 36

How are neurons of the auditory cortex arranged?

Answer 36

Tonotopically. Neurons sensitive to higher pitch arranged further along surface, towards back of brain.

Question 37

What is Conductive Hearing Loss?

Answer 37

Inability of either tympanic membrane, or ossicles, to vibrate

Question 38

Sensorineural Hearing Loss?

Answer 38

damage to cilia of hair cells caused by prolonged loud noise

Question 39

Tinnitus?

Answer 39

A ringing or buzzing sensation either idiopathic or from damage to cilia. May or may not be temporary.

Question 40

Cochlear implant?

Answer 40

Tiny strip of electrodes implanted alongside basilar membrane. Bypassess damaged cilia.

Question 41

Binaural neurons

Answer 41

receive inpt from both ears. Therefore can compare intensity difference and estimate location

Question 42

Frequency Theory

Answer 42

oscillation of basilar membrane same as source But theory doesn't hold for how can hear higher pitches as hair cells can't fire that fast

Question 43

Volley Principle

Answer 43

ensembles of hairs can collectively code for pitch

Question 44

Place Theory

Answer 44

basilar membrane stiffer at apex.therefore more high frequency at base. Therefore cilia location also codes for pitch

Question 45

Neurons of secondary auditory cortex

Answer 45

integrate outputs from multiple neurons from primary auditory cortex and thalamus, to detect complex sounds, such as speech.

Question 46

taste and smell receptors

Answer 46

Cheoreceptors. lock and key model. May become permanently locked but taste buds and epithelial cells are very rapidly replaced.

Question 47

list taste types

Answer 47

sweet, sour, salty, bitter, piquancy (spiciness), umami (savoury)

Question 48

olfactory receptor cells

Answer 48

100"s of specialised types.Their tendrils extend out of the epithelium into the air.

Question 49

Olfactory and gustatory cortex

Answer 49

adjacent . between temporal and frontal lobes. Interact and interconnect with areas of spatial memory, therefore strong link between smells and emotional memory. smell and taste work together to form perception of taste/smell.

Question 50

touch

Answer 50

diverse range of mechanoreceptors in skin.

Question 51

proprioceptors

Answer 51

respond to movement/strain in muscles, tendons, joints

Question 52

mechanoreceptors in vestibular system

Answer 52

detect fluid rushing in semicircular canals due to head movement

Question 53

nociceptors

Answer 53

have free nerve endings in many areas of body, to detect pain.

Question 54

Pain

Answer 54

Processed by many parts of spinal cord, subcortical brain, and cortical brain. Sometimes only as far as spinal cord, therefore generate a reflex

Question 55

Gate Control Theory of Pain

Answer 55

Neuronal pain signals compete with signals of touch/pressure/vibration. The experience of pain also influenced by context and expectation, level of attention etc etc.

Question 56

Placebo effect

Answer 56

believe treatment will work, so expect eg less pain, so eg experience less pain

Question 57

nocebo effect

Answer 57

pain experienced on the expectation of pain but not on its actual delivery.

Question 58

visual agnosias

Answer 58

visual perception problems. normal vision but difficulty organising shapes, colours,patterns, into integrated precepts of object recognition

Question 59

apperceptive visual agnosia

Answer 59

eg difficulty identifying object in cluttter or superimposed environment. eg difficulty identifing an object viewed fro an abnormal angle. eg. difficulty identifying object when there is extensive shadowing

Question 60

associative visual object agnosia

Answer 60

can recognise objects, can cope with clutter and shadowing, but can't draw an object from memory and can't identify function of visualised objects. Problem linking object perception with object knowledge.

Question 61

prosopagnosia

Answer 61

subtype of associative agnosia. Inability to recognise faces, even sometimes their own

Question 62

Integrative agnosia

Answer 62

problem both with apperceptive and associative agnosia

Question 63

auditory agnosia

Answer 63

difficulties recognising/understanding sounds/language

Question 64

tactile agnosia

Answer 64

difficulty recognising objects by touch

Question 65

anosognosia

Answer 65

difficulty in perceiving damage or illness in one's own body.eg. stroke victim cannot move right arm but is completely unaware of inability and denies it.