Psychophysics

Question 1

How to measure stimulus magnitude

Answer 1

1. ) present stimulus to participant, ask them to assign it a perceptual value
2. ) present a different stimulus, ask participant to rate magnitude in comparison to first stimulus

Question 2

What is Stevens power law

Answer 2

p=KS^n

Question 3

How to find a stimulus threshold - method of limits

Answer 3

Pick a low or high stimulus, successively increase intensity, take a record of when the participant can detect the stimulus. Mark down the first point the stimulus is detectable

Question 4

How to find a stimulus threshold - method of adjustment

Answer 4

Participant adjusts the stimulus themselves and notes the first point they can detect the stimulus

Question 5

How to find a stimulus threshold - method of constant stimuli

Answer 5

Stimuli are pre-selected by experimenter and run in a random order. Participant must say if they can detect stimulus or not

Question 6

How to find the just noticeable difference

Answer 6

Present two stimuli on each trial, ask participant whether they are the same of different.

Question 7

What is Weber’s law

Answer 7

ΔP/P=K The law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus, no matter if the intensity is large or small

Question 8

What does a receiver operating characteristics curve show

Answer 8

That all participants sensitivity to the stimulus is the same, the only difference is the way they are answering thequestions. A liberal participant says yes even if they’re not sure if they detected the stimulus and a conservative participant says yes only when they are 100% meaning they may not say they have heard detectable stimuli