L4 - Measuring Performance

Question 1

How to measure a subject measures?

Answer 1

• Likert Scales: Bimodal, an odd number of options, labelled levels
• Anchored Scale: endpoints are labelled e.g not at all/ a lot. Limited number of responses
• Visual Analogue Scale. Endpoints are labelled, just a line and person drags.

Question 2

What is psychophysics

Answer 2

• Relating a physical experience or stimulus to an activation in the brain, and experience of sensation.

Question 3

Typical questions from psychophysics

Answer 3

• Absolute threshold: how much of something can be detected
• Difference threshold: how much can something be changed before the change is detected?

Question 4

How to measure difference threshold?

Answer 4

• Pairs are presented with one always the same and ppt indicates if they are the same or diff.
• Two alternative force choice task
  Discrimination made at 75% rather than 50%

Question 5

Describe the Staircase method

Answer 5

• Start with pairs that are easily discriminated
• Move them closer until they are not discriminated.
• Should match up with the correct %

Question 6

Describe Signal Detection Theory

Answer 6

• Not all responses/absence to a stimulus are correct.
• Goes beyond proportion to tell us discrimination of stimuli
• Assumes there is noise around stimulus

Question 7

How this is this represented?

Answer 7

A two by two table, like a contingency table
Also depends on discrimination

Question 8

What are the SDT outcomes?

Answer 8

• Discrimination: how easy the task is (how much the curves overlap)
• Criterion: the level the participant is using to make the decision

Question 9

How to measure speed of response?

Answer 9

• Donder’s Method of Subtraction: go/nogo, keep adding cog processes to see time change
• Additive Factors Method: if two things affect the same processing.