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Cognitive Psychology > Psycho-physics > Flashcards

Psycho-physics Flashcards

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1
Q

What is the psychophysical function?

A

The relation between INTENSITY OF STIMULI and the MAGNITUDE OF SENSATION FELT

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2
Q

Who was the ‘Just noticeable difference’ first described by?

A

Weber

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3
Q

The intensity level of stimulus may play a role in the just noticeable difference.

If a light is very dim…

A

You will be more likely to notice a change in intensity

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4
Q

If a BRIGHT LIGHT was turned up

And a dim light was turned up, by the same amount

Which change are you likely to notice?

A

Dim light

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5
Q

Weber fraction

A

As stimulus intensity increases, threshold for noticing it (difference threshold) will also increase (constant proportion)

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6
Q

What kind of relationship is the Weber fraction?

A

A linear relationship

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7
Q

Weber Fraction -

As the ratio between the magnitudes of two stimuli increases…

A

The more easily the difference between the two stimuli will be perceived

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8
Q

The just noticeable difference is subject to…

A

Individual differences

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9
Q

What is signal detection theory?

A

The ability to differentiate between informative stimulus and background/random patterns

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10
Q

What is the signal detection theory relevant to?

A

Any domain where a detector wishes to make a judgement about a stimulus

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11
Q

What are the four possible outcomes of signal detection theory?

A

HIT
CORRECT REJECTION
MISS
FALSE ALARM

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12
Q

Signal Detection Theory

What are we aiming for?

A

HITS and CORRECT REJECTIONS

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13
Q

A radiologist is examining a CT scan for tumours.

What theory is the radiologist adopting?

A

Signal detection theory

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14
Q

What might increase the chances of getting a Hit or a Correct Rejection?

A

Information acquisition

Increasing criterion

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15
Q

How can the criterion be adjusted (STD)?

A

When experimenter is in control of how much info they receive

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16
Q

When the experimenter is in control of how much information they receive, the choices are not difficult and they can pick a criterion to…

A

Get a nearly perfect hit rate

Almost no false alarms

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17
Q

The most widely used measure of sensitivity is…

A

D prime

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18
Q

What is D prime

A

A measure of sensitivity

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19
Q

D prime allows for comparison…

A

between different people

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20
Q

If a signal is ABOVE our criterion, we will…

A

Detect it

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21
Q

What is the criterion?

A

The internal threshold against which one judges a stimuli

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22
Q

Do people have a different criterion?

A

Yes

Subjective

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23
Q

Why can’t we always make perfect decisions?

A

Tradeoff

There will always be ‘system noise’

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24
Q

ROC curves capture various alternatives available to an individual as they….

A

Move their criterion up and down the scale

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25
Q

If the criterion is very HIGH, the…

A

Low false alarm rate

Low hit rate

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26
Q

If the criterion is very LOW, the…

A

High false alarm rate

High hit rate

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27
Q

If the criterion is intermediate…

A

Hit/false alarm rate will take on intermediate values

28
Q

What is an example of SDT and hits/false alarms in terms of statistics?

A

Type 1 and Type 2 errors

29
Q

Define ‘absolute threshold’

A

Smallest amount of stimulus energy necessary to detect it

30
Q

What are psychometrics?

A

Measurement of psychological qualities

31
Q

What is the JND?

A

Min amount stimulus intensity must be changed in order to notice

32
Q

3 basic methods for determining absolute threshold

A

methods of limits
adjustment
constant stimuli

33
Q

What is sensitivity?

A

Being able to detect a stimulus/differentiate between stimulus and absence

34
Q

What kind of task is SDT used in?

A

Judgement task

35
Q

We want to maximise…..

And minimise…

A

Hits
Correct rejections
False alarms
Misses

36
Q

Which type of eyewitness identification originally was thought to reduce false alarms?

A

Sequental presentation

^ This is wrong

37
Q

What is the statistic that gives you a measure of sensitivity?

A

d’

38
Q

what is the d prime calculation?

A

Z(hits) - Z(false alarms)

39
Q

A small d prime would indicate….

A

More mistakes

40
Q

What is an ROC curve used to calculate?

A

D prime

41
Q

The psychophysical approach to perception focuses on…

A

Relationship between STIMULI and PERCEPTUAL RESPONSES

42
Q

Absolute threshold

A

Smallest amount of stimulus energy needed to detect it

43
Q

Smallest amount of stimulus energy needed to detect it

What is this?^

A

Absolute threshold

44
Q

The smallest difference between two stimuli that a person can detect

A

The difference threshold

45
Q

The difference threshold is..

A

The smallest difference between two stimuli that a person can detect

46
Q

When the difference between a standard and a comparison weight is small, it will be difficult to…

A

Detect the difference in the weights

47
Q

If the DL (difference threshold) for an 100g weight is 2g, what would the difference threshold be for a 200g weight and why?

A

4g

Constant proportion

48
Q

The ratio of the difference threshold and the standard stimulus is constant. This is called the…

A

Weber fraction

49
Q

Magnitude estimation is…

A

Measure of relationship between magnitude PERCEPTION and actual stimulus intensity

50
Q

Doubling the intensity of a light does not necessarily double…

A

The perceived brightness

51
Q

Doubling the intensity of a light does not necessarily double the perceived brightness. This is called…

A

Response compression

52
Q

Some perceptual research use methods that require the observer to respond as quickly as possible to a scene. This is called

A

Visual search

53
Q

An everyday example of a visual search would be

A

Searching for a friends face in a crowd

54
Q

When it comes to detecting stimulus, every person has a different…

A

Response criterion

55
Q

Is response criterion the same as sensitivity?

A

No

56
Q

If the response criteria of two different people is different, can their sensitivity be the same?

A

Yes

57
Q

If you have a low criterion, you are more likely to make…

A

False alarms

Less correct rejections

58
Q

If you have a high criterion, you are more likely to make…

A

Less hits but also less false alarms

59
Q

If you have a VERY high criterion, there will be more…

A

Correct rejections

60
Q

A correct rejection is saying

A

No when there is no tone/stimulus

61
Q

A persons sensitivity is indicated by the _____ of the ROC curve

A

Shape

62
Q

The shape of the ROC curve indicates a persons

A

Sensitivity

63
Q

Why can noise often be mistaken for the signal? SDT)

A

The signal is usually very faint and hard to detect

64
Q

In an SDT experiment, will the intensity of the tone shift?

A

No - it will remain constant

65
Q

Criterion may be one of three forms: L, N and C

A

Liberal
Neutral
Conservative

66
Q

What shape will an ROC curve be if a person is more sensitive (their d prime is high)

A

Bowed

67
Q

A high d prime would indicate that an individual is more

A

Sensitive

Cognitive Psychology (10 decks)

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