Magnitude Rating

Question 1

What did Smith Stevens modify to measure magnitude?

Answer 1

He started giving an initial stimulus from which the subject could then compare the following stimuli and rate them.

Question 2

How is called that initial measure of stimulus given to the patient?

Answer 2

Modulus or Standard Stimulus

Question 3

Stevens’ Power Law

Answer 3

Question 4

In Stevens’ Power Law

What does every parameter stand for?

Answer 4

R: Response

S: Stimulus magnitude

b: Controls the curvature of the function
a: corrects for the scaling of measurement units used for S. It is also related to the modulus

Question 5

Does this mean that Fechner’s formula is not relevant anymore?

Answer 5

No, Stevens’ Law also involves Fechner’s.

Notice that

Most are logarithmic but some (like pain) are exponential.

Brightness is logarithmic since at some point brightness becomes unnatural.

Moreover, if the exponent is >1 it will be exponential. If 0 < b < 1 it will be logarithmic.

Question 6

Stevens’ Law can also be divided into two parts:

What is the name of the letter psy?

Answer 6

Perceived Intensity

Question 7

Absolute Magnitude Ratings

Answer 7

Similar to Stevens’ method but instead of giving just one stimulus you give two stimuli

Question 8

Name a solution to the problem of comparing two people’s ratings.

(ex: supertasters and normal people)

Answer 8

Cross modality matching

Question 9

Cross Modality matching

Answer 9

Researchers ask the patients to rate their sensation by comparing it to another sensation felt with different preceptors.