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PSYC 367 > MT 1 > Flashcards

MT 1 Flashcards

1
Q

perceptual illusion

A

a discrepancy between what is perceived and what is physically present in the real world

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2
Q

optical illusion

A

a discrepancy between what is in the retinal image and what is
present in the real world
e.g., rainbow
you are viewing what is on your retina accurately

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3
Q

what’s the difference between perception and sensation

A
  • sensation: ability to detect a stimulus, and perhaps to turn that detection into a private experience
  • perception: giving meaning to a detected sensation
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4
Q

psychophysics

A
  • the science of defining quantitative relationships between physical and psychological (subjective) events
  • Psychophysics is interested in what the brain is doing, not how it does it… so it ignores the physiological response stage
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5
Q

absolute threshold

A

minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time

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6
Q

psychometric function

A

a graph of stimulus value (e.g. intensity) on the horizontal axis versus the subject’s responses (e.g. proportion “yes”) on the vertical axis

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7
Q

ogive

A

the typical s-shape of a psychometric function

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8
Q

list the techniques available to study each step of the sensory
process

A
  1. physical stimulus –> physiological response
    - mostly animal single-unit recording
    - magnetoencephalography
    - positron emission tomography
    - functional magnetic resonance
    - imaging event-related potentials
  2. physiological process –> sensory experience
    - animal lesion studies
    - human clinical studies
    - human brain imaging
  3. physical stimulus –> sensory experience
    - behavioural techniques
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9
Q

difference threshold

A

the smallest difference between stimuli or change in a stimulus that the observer noticed 50% of the time (also called a just noticeable difference [JND])

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10
Q

suprathreshold stimulus

A

for sensory discrimination, this is above the absolute threshold and is always detectable

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11
Q

what are the main differences between measuring DETECTION thresholds with the method of constant stimuli, the method of limits, and the method of adjustment

A
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12
Q

how to use the method of constant stimuli to measure detection thresholds

A
  • select stimulus intensities above and below expected threshold
  • present many trials of each intensity in random order
  • plot psychometric function; read 0.50 (or 50%) detected point from graph
  • what is the weakest stimuli you can detect?
  • the lower the absolute threshold, the higher the person’s sensitivity
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13
Q

how to use the method of limits to measure detection thresholds

A
  • starts with the descending series: stimulus intensity decreased in equal steps until response changes to “no”
  • after, it changes into an ascending series: stimulus intensity increased in equal steps until response changes to “yes”
  • alternate between ascending & descending series; vary start point
  • crossover point calculated for each series
  • when the yes changes to no, or vice versa
  • absolute threshold is the average of all crossover points
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14
Q

how to use the method of adjustment to measure detection thresholds

A
  • observer adjusts stimulus intensity, using a potentiometer, until it is just detectable
  • potentiometers you can encounter everyday… eg, volume dial
  • experimenter randomly adjusts starting point (position of potentiometer)
  • calculate average (mean) of these threshold adjustments
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15
Q

who was Fechner and what did he do

A
  • Fechner’s use of Weber’s findings to describe sensation
  • Fechner’s Law: a principle describing the relationship between stimulus magnitude and
    resulting sensation magnitude (scaling)
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16
Q

what are the classical methods of psychophysics

A
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17
Q

What is Fechner’s Law? What is it’s equation?

A

Fechner’s Law: a principle describing the relationship between stimulus magnitude and resulting sensation magnitude (scaling)

as stimulus intensity increases, sensation intensity increases rapidly at first, but then more slowly

S = k log R
S = sensation intensity
k = Weber fraction
R = stimulus level

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18
Q

what is magnitude estimation

A

participant assigns a number to describe stimulus intensity
- demonstration: whiteness of standard dot pattern is 100
- An easier technique!
* assign number to perceived whiteness of each comparison dot pattern
* more white should be >100; less white <100

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19
Q

What is Stevens’ power law

A

the magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent (or power)
- all of these can be described using stevens’ power law
- S = aIb
- S = sensation
- a= constant
- I = stimulus intensity
- b = exponent (determines the shape of the curve) … this is what changes between different stimuli

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20
Q

what is cross-modality matching

A

a scaling method in which the intensities of sensations that come from different sensory modalities are matched

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21
Q

where are catch trials, and what does hit or miss mean in this context

A

trials in a signal detection experiment on which the stimulus/signal is absent
- hit: signal present; sensory activity to the right of criterion
- miss: signal present; activity to the left of criterion

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22
Q

what is sensitivity in the context of detecting signals

A
  • ease with which a perceiver can tell the difference between the presence and absence of a stimulus
  • depends on overlap of signal absent and signal present distributions
  • doesn’t depend on motivation!
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23
Q

what is the difference between a false alarm and a correct rejection, and how does this relate to a hit or miss

A

both are when the signal is absent
false alarm: response yes
correct rejection: response no

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24
Q

what is the statistic d’

A
  • the statistic that reflects a perceiver’s sensitivity (not usually calculated by hand)
  • hits and false alarms should be equal if the participant cannot tell the difference between stimuli
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25
Q

what is endogenous noise

A
  • spontaneous neural activity; affects measurement of thresholds & sensitivity
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26
Q

what is criterion

A
  • Beta
  • response bias within a perceiver; depends on expectations & motivation
  • can manipulate this within an individual person by messing with their expectations and motivation
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27
Q

What is Beta and what does it relate to?

A

beta is criterion
relates to degree of response bias within a perceiver

the bigger the beta, the more strict the criterion

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28
Q

How does Fechner’s law relate to Weber’s law? give a definition of both laws

A

Fechner’s Law: a principle describing the relationship between stimulus magnitude and resulting sensation magnitude (scaling)

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29
Q

what is a magnitude estimation experiment? How does this relate to Stevens’ power law?

A
  • participant assigns a number to describe stimulus intensity
  • magnitude estimation experiments showed that once detected, the sensory magnitude of a stimulus increases with its physical magnitude, within limits but rate of increase varies with different sensations
  • different for different sensory modalities
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30
Q

explain the discrepancy between Stevens’ and Fechner’s scaling results

A

Stevens’ law and Fechner’s law predict the same scaling result for sensory modalities in which b < 1, but not for other sensory modalities
- they match up only for some sensory modalities
possible reasons for the discrepancy:
* Fechner’s law assumes that all JNDs are perceptually equal, but this law is violated for some sensory modalities
* magnitude estimation is more subjective than determining JNDs

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31
Q

what are the 4 classes of responses in a signal detection experiment

A
  • hit
    -miss
  • false alarm
  • correct rejection
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32
Q

State the difference between sensitivity (d’) and criterion (ß), and describe the effect of stimulus probability on each

A
  • sensitivity is the ease with which a perceiver can tell the difference between the presence and absence of a stimulus
  • criterion is like alpha–it’s the point at which the perceiver decides that X is a real sound and not them hallucinating
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33
Q

Describe signal detection theory in terms of the hypothetical distributions underlying performance. Show how d’, criterion, hits, false alarms, misses and correct rejections are represented on these distributions

A
  • assumes that endogenous noise (N) has a normal (bell-shape) distribution
  • N represents sensory activity during catch trials
  • when signal is present, it adds to the noise (S+N)
  • sensory activity for signal + noise is, on average, more intense than noise alone
  • but noise can produce sensation as strong as that produced by the signal (could be endogenous + external noise)
  • it can change due to fatigue or external noise
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34
Q

receiver operating characteristic (ROC) curve

A

raphical plot of hit rate as a function of false
alarm rate for different criterion values in a signal detection experiment; d’ is constant and
criterion is changing along each curve

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35
Q

transduction

A

how energy in the environment gets transformed into electrical energy by the nervous system

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36
Q

information processing

A

what happens to the electrical signals as they travel through the nervous system to the brain

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37
Q

sensory coding

A

how the brain understands what the electrical signals reaching it mean

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38
Q

doctrine of specific nerve energies

A
  • the nature of a sensation depends on which nerves are stimulated, not on how the nerves are stimulated
  • seems logical because neural signals are identical across sensory modalities
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39
Q

synapse

A

junction between neurons that permits information transfer

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40
Q

neurotransmitter

A

chemical substance used in neuronal communication at synapses

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41
Q

action potential

A

rapid depolarization of membrane potential

42
Q

lesion

A
42
Q

compression

A

air molecules bunch together (high air pressure)

43
Q

rarefaction

A

air molecules spread apart (low air pressure)

44
Q

phase

A

part of cycle the sound pressure wave has reached at a given point in time; measured in degrees ̊

45
Q

amplitude

A

maximum pressure change of wave above normal

46
Q

frequency

A

rate of fluctuation of sound pressure; measured in cycles/second or Hertz (Hz)

47
Q

sound pressure

A
48
Q

sound pressure level

A

sound pressure level (amplitude or intensity)
- relative measure
- ratio of sound pressures converted to log scale–decibels (dB)
dB = 20 * log (P/Po) or dB = 10 * log (P2/Po2)
(P is sound pressure of tone; Po is reference pressure of 0.0002 dynes/cm2 or 0.00002 pascal)

49
Q

Define receiver operating characteristic (ROC) curve, and describe how sensitivity and
criterion are represented

A
50
Q

List the 7 sensory cranial nerves and show how they illustrate the doctrine of specific nerve
energies

A

7 pairs of cranial nerves carry sensory information
sensory only
- Olfactory (I)
- Optic (II)
- Vestibulocochlear (VIII) - auditory + vestibular nerves

sensory & motor
- Trigeminal (V)
- Facial (VII)
- Glossopharyngeal (IX)
- Vagus (X)

doctrine of specific nerve energies: e.g. stimulation of optic nerve, by light or a finger, produces the sense of vision

51
Q

Define synapse, neurotransmitter and action potential, and describe how neurons communicate
with each other

A
  • presynaptic neuron sends electrical impulse to the postsynaptic neuron
52
Q

Compare and contrast the 4 neuroimaging techniques for studying human brain function.

A
  • event-related potentials
  • eegs
  • good temporal resolution, bad spatial resolution
  • magnetoencephalography
  • similar to EEGs but uses magnets
  • good temporal resolution, even better than EEG
  • good spatial resolution if used with MRI
  • positron emission tomography
  • functional magnetic resonance imaging
  • bad temporal resolution
  • good spatial resoltuion
53
Q

Indicate frequency, amplitude and phase on a diagram of a simple sine wave, and define sound
pressure level. List the units of measurement for each feature

A
  • frequency: rate of fluctuation of sound pressure; measured in cycles/second or Hertz (Hz)
  • phase: part of cycle the sound pressure wave has reached at a given point in time; measured in degrees ( ̊ )
  • amplitude: maximum pressure change of wave above normal
  • atmospheric pressure; several different units (see slide 27)
54
Q

Describe 4 types of computational models that have been applied to the study of sensation and
perception

A
55
Q

Fourier’s theorem

A

most sounds are complex and can be described as a set of sine waves

56
Q

Fourier analysis

A

mathematical procedure for separating a complex pattern into component sine waves that vary over

57
Q

fundamental frequency

A

lowest sine-wave frequency in a complex sound; usually determines perceived pitch

58
Q

harmonics

A

higher frequency sine-wave components; integer multiples of fundamental frequency

59
Q

timbre

A

differences in frequency & amplitude of harmonics determines psychological attribute of quality

60
Q

impedance matching

A

middle ear amplifies sound energy to reduce loss due to reflection at oval window (air/fluid boundary)

61
Q

acoustic reflex

A

in response to prolonged loud sounds, tensor tympani & stapedius muscles contract to reduce magnitude of auditory signal transmitted to inner ear

62
Q

afferent fibres

A
  • afferent fibres carry sensory information to central nervous system
  • 90% connected to inner hair cells (Type I)
  • 10% connected to outer hair cells (Type II)
63
Q

efferent fibres

A
  • carry information from central nervous system to inner ear
  • comprise most neurons synapsing with outer hair cells
64
Q

graded potential

A

slow change in membrane voltage that varies in size (not all-or-nothing); occurs in hair cells

65
Q

List the normal human range for sound frequency. Name the psychological properties corresponding to sound frequency and to sound pressure level, respectively.

A
  • Humans: 20-20,000 hz
66
Q

Define Fourier’s theorem and Fourier analysis, and relate these concepts to complex sounds and timbre.

A
  • Fourier said that all sound waves are a set of mixed sine waves.
  • pure sounds is just one sine wave, but complex sounds are multiple
  • timbre is due to differences in frequency and amplitude
67
Q

Describe 2 ways in which the middle ear functions to amplify the sound pressure reaching the inner ear.

A
  • impedance matching: middle ear amplifies sound energy to reduce loss due to reflection at oval window (air/fluid boundary)
  • ossicles act like levers, increases force at stapes by a factor of 1.3 (like a teeter totter)
68
Q

Define the acoustic reflex and name the 2 muscles involved.

A

in response to prolonged loud sounds, tensor tympani & stapedius muscles contract to reduce magnitude of auditory signal transmitted to inner ear

69
Q

Compare and contrast the anatomical arrangement and innervation of the inner and outer hair cells.

A
70
Q

Describe the transduction of mechanical energy into action potentials in the cochlea.

A
  • hair cells have no axons, but release neurotransmitter at synapse with dendrites of auditory nerve fibres
  • axons of auditory nerve fibres form auditory (cochlear) nerve [part of 8th cranial vestibulocochlear nerve]
  • transduction occurs when stereocilia are bent
  • when basilar membrane moves up & down, hair cell stereocilia bend back & forth against tectorial membrane
71
Q

Describe the response of the basilar membrane to sounds of different frequencies.

A
72
Q

what is the process of sensation

A

physical stimulus –> physiological response –> sensory experience

73
Q

what is the difference between difference thresholds and absolute thresholds

A

both are trying to find the minimal stimulus where the participant can detect the stimulus 50% of the time….
but the absolute threshold is purely about detection
whereas the difference threshold is about when the participant can detect the difference between 2 stimuli

74
Q

what is the benefit of using the method of limits to study sensory detection

A

Saves time because you don’t need to find the psychometric function! Here, you can just narrow in on the absolute threshold

75
Q

how to use the method of constant stimuli to study sensory DISCRIMINATION

A
  • standard (fixed value) and comparison (value changes) stimuli presented together
  • magnitude of comparison (values above & below standard ) varied in random order with many trials of each value
  • plot proportion “bigger” responses versus comparison magnitude
76
Q

pros and cons of using the method of constant stimuli to study sensory DISCRIMINATION

A

advantages
- accurate & repeatable threshold values
disadvantages
- time consuming
- not good for tracking thresholds that change over time
- not good for children or clinical patients
- lots of data collected far from threshold (inefficient)

77
Q

how to use method of limits to study sensory discrimination

A
  • standard and comparison stimuli presented together
  • descending series: comparison decreased in equal steps until response
  • changes from “stronger” to “equal” to “weaker”
  • 2 stimuli, but this trial order is not random
  • ascending series: comparison increased in equal steps until response
  • changes from “weaker” to “equal” to “stronger”
  • alternate between descending & ascending series; vary starting point
  • upper limit is crossover point between “stronger” & “equal” on each series
  • lower limit is crossover point between “equal” & “weaker” on each series
78
Q

what is subjective equality

A

measure of accuracy

79
Q

pros and cons of the method of limits for sensory discrimination

A

Advantages
* Saves time(efficient);
* don’t have to trace out whole psychometric function
disadvantages
* error of habituation
* make same response too many times
* (alternate the series to reduce; requires extra series)
* Error of anticipation
* change response after fixed number of trials
* (vary starting point to reduce; requires extra stimulus levels)

80
Q

what is the method of adjustment for sensory discrimination

A
  • observer adjusts comparison stimulus until it matches the standard stimulus
  • experimenter randomly varies starting point
  • Main difference is that the participant is now in charge
81
Q

pros and cons of the method of adjustment

A

advantages
* quick
* participants like it
disadvantages
* not very accurate or repeatable
* used to get initial idea of where a threshold is… and then the experimenters use another method
* not used as much due to inaccuracy

82
Q

how is JND and PSE calculated for the 3 types of experiments

A
83
Q

pros and cons of the method of adjustment

A

advantages
* quick
* participants like it
disadvantages
* not very accurate or repeatable
* used to get initial idea of where a threshold is… and then the experimenters use another method
* not used as much due to inaccuracy

84
Q

describe the staircase method and its problem

A
  • starts out like method of limits
  • stimulus intensity decreased (or increased) in equal steps until stimulus can’t be detected
  • then, stimulus intensity increased (decreased) until stimulus can be detected, etc.
  • adaptive method - stimuli kept hovering around threshold by adapting test sequence to participant’s responses
  • change what’s given to the participant based on what they say that they can see
85
Q

what is a response reversal?

A

point where a response changes
run ends after fixed # of reversals or fixed # of trials

86
Q

what is an absolute threshold in the context of the staircase method

A

is the average of the cross-over points at response reversals (eg. 63.5, 63.5, 61.5, 61.5)

87
Q

advantages and disadvantages of the staircase method

A

advantages
* efficient;
* most data collected around threshold
* other methods have you collect data far from thresholds
* can be used to track threshold changes over time
disadvantages
* errors of anticipation and habituation… the same as the method of limits

88
Q

what are some modern improvements to the staircase method

A

to avoid anticipation and habituation errors, randomly interleaved descending and ascending staircases can be used

89
Q

yes/no paradigm

A

everything you’ve seen so far
- participant reports presence or absence of stimulus (detection) or stimulus difference (discrimination)
- very subjective
- experimenter can’t verify or dispute participant’s response

90
Q

2-alternative forced-choice paradigm

A
  • more objective
  • participant must prove they can detect or discriminate the stimulus
  • detection - “is the circle on the left or the right?”; “was the tone in the first or second interval?”
  • discrimination – “in which interval are the 2 stimuli different?”
91
Q

advantages of the 2-alternative forced-choice paradigm

A
  • more accurate thresholds
  • reduces non-sensory differences between participants (bias or criterion differences)
92
Q

what is Weber’s law

A

Weber’s law: the difference threshold is a constant proportion of the physical magnitude of the stimulus

DI = k I
DI is the difference threshold (JND)
I is the physical magnitude of the stimulus
k is a constant that depends on the sensory system

93
Q

what does a small beta produce?

A
  • lax criterion
  • high hits and low false alarms
94
Q

what does a large beta produce?

A
  • strict criterion
  • low hits and low false alarms
95
Q

how does motivation affect signal detection theory

A
  • affects criterion, not sensitivity
  • strong motivation = small beta
96
Q

describe EEG

A
  • electrodes on scalp;
  • subject performs perceptual task
  • non-evasive
  • measures populations of neurons
  • when EEG action and it’s related to a task, it’s called an event-related potential
97
Q

describe an MEG

A
  • is also about electronic energy around neurons
  • contains magnetometers
    o arrays of superconducting quantum interference devices (SQUID)
  • measures magnetic fields created by the flow of ion currents between neurons
  • high temporal resolution; use with MRI for good spatial resolution
    o better temporal resolution compared to EEG!
  • difficult to measure signals deep in brain
98
Q

positron emission tomography (PET)

A
  • as tracer decays, positrons are emitted and picked up by scanner
  • areas of high radioactivity are associated with neural activity (based on blood flow)
  • good for studying disease or brain chemicals
  • poor spatial resolution, but can be improved if used with MRI
  • invasive procedure
99
Q

functional magnetic resonance imaging (fMRI)

A
  • non-invasive procedure;
  • best spatial resolution;
  • response changes very slowly
  • neural activity -> blood flow and volume -> oxygen consumption -> oxygen in venous blood (gets redder) -> stronger MRI signal
100
Q

what is phase often used for

A

to compare the timing of 2 sound waves

101
Q
A

PSYC 367 (1 decks)

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