Psycho-physics

Question 1

What is the psychophysical function?

Answer 1

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

Question 2

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

Answer 2

Weber

Question 3

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

If a light is very dim…

Answer 3

You will be more likely to notice a change in intensity

Question 4

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?

Answer 4

Dim light

Question 5

Weber fraction

Answer 5

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

Question 6

What kind of relationship is the Weber fraction?

Answer 6

A linear relationship

Question 7

Weber Fraction -

As the ratio between the magnitudes of two stimuli increases…

Answer 7

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

Question 8

The just noticeable difference is subject to…

Answer 8

Individual differences

Question 9

What is signal detection theory?

Answer 9

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

Question 10

What is the signal detection theory relevant to?

Answer 10

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

Question 11

What are the four possible outcomes of signal detection theory?

Answer 11

HIT
CORRECT REJECTION
MISS
FALSE ALARM

Question 12

Signal Detection Theory

What are we aiming for?

Answer 12

HITS and CORRECT REJECTIONS

Question 13

A radiologist is examining a CT scan for tumours.

What theory is the radiologist adopting?

Answer 13

Signal detection theory

Question 14

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

Answer 14

Information acquisition

Increasing criterion

Question 15

How can the criterion be adjusted (STD)?

Answer 15

When experimenter is in control of how much info they receive

Question 16

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

Answer 16

Get a nearly perfect hit rate

Almost no false alarms

Question 17

The most widely used measure of sensitivity is…

Answer 17

D prime

Question 18

What is D prime

Answer 18

A measure of sensitivity

Question 19

D prime allows for comparison…

Answer 19

between different people

Question 20

If a signal is ABOVE our criterion, we will…

Answer 20

Detect it

Question 21

What is the criterion?

Answer 21

The internal threshold against which one judges a stimuli

Question 22

Do people have a different criterion?

Answer 22

Yes

Subjective

Question 23

Why can’t we always make perfect decisions?

Answer 23

Tradeoff

There will always be ‘system noise’

Question 24

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

Answer 24

Move their criterion up and down the scale

Question 25

If the criterion is very HIGH, the...

Answer 25

Low false alarm rate | Low hit rate

Question 26

If the criterion is very LOW, the...

Answer 26

High false alarm rate | High hit rate

Question 27

If the criterion is intermediate...

Answer 27

Hit/false alarm rate will take on intermediate values

Question 28

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

Answer 28

Type 1 and Type 2 errors

Question 29

Define 'absolute threshold'

Answer 29

Smallest amount of stimulus energy necessary to detect it

Question 30

What are psychometrics?

Answer 30

Measurement of psychological qualities

Question 31

What is the JND?

Answer 31

Min amount stimulus intensity must be changed in order to notice

Question 32

3 basic methods for determining absolute threshold

Answer 32

methods of limits adjustment constant stimuli

Question 33

What is sensitivity?

Answer 33

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

Question 34

What kind of task is SDT used in?

Answer 34

Judgement task

Question 35

We want to maximise..... | And minimise...

Answer 35

Hits Correct rejections False alarms Misses

Question 36

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

Answer 36

Sequental presentation ^ This is wrong

Question 37

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

Answer 37

d'

Question 38

what is the d prime calculation?

Answer 38

Z(hits) - Z(false alarms)

Question 39

A small d prime would indicate....

Answer 39

More mistakes

Question 40

What is an ROC curve used to calculate?

Answer 40

D prime

Question 41

The psychophysical approach to perception focuses on...

Answer 41

Relationship between STIMULI and PERCEPTUAL RESPONSES

Question 42

Absolute threshold

Answer 42

Smallest amount of stimulus energy needed to detect it

Question 43

Smallest amount of stimulus energy needed to detect it What is this?^

Answer 43

Absolute threshold

Question 44

The smallest difference between two stimuli that a person can detect

Answer 44

The difference threshold

Question 45

The difference threshold is..

Answer 45

The smallest difference between two stimuli that a person can detect

Question 46

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

Answer 46

Detect the difference in the weights

Question 47

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

Answer 47

4g Constant proportion

Question 48

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

Answer 48

Weber fraction

Question 49

Magnitude estimation is...

Answer 49

Measure of relationship between magnitude PERCEPTION and actual stimulus intensity

Question 50

Doubling the intensity of a light does not necessarily double...

Answer 50

The perceived brightness

Question 51

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

Answer 51

Response compression

Question 52

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

Answer 52

Visual search

Question 53

An everyday example of a visual search would be

Answer 53

Searching for a friends face in a crowd

Question 54

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

Answer 54

Response criterion

Question 55

Is response criterion the same as sensitivity?

Answer 55

No

Question 56

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

Answer 56

Yes

Question 57

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

Answer 57

False alarms | Less correct rejections

Question 58

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

Answer 58

Less hits but also less false alarms

Question 59

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

Answer 59

Correct rejections

Question 60

A correct rejection is saying

Answer 60

No when there is no tone/stimulus

Question 61

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

Answer 61

Shape

Question 62

The shape of the ROC curve indicates a persons

Answer 62

Sensitivity

Question 63

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

Answer 63

The signal is usually very faint and hard to detect

Question 64

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

Answer 64

No - it will remain constant

Question 65

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

Answer 65

Liberal Neutral Conservative

Question 66

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

Answer 66

Bowed

Question 67

A high d prime would indicate that an individual is more

Answer 67

Sensitive