Study Guide for Appendix

Know the key terms on page 568.

1.         What was Fechner’s basic goal?

2.         What is Weber’s law and how is it applied (you need to be able to make         some simple calculations regarding the JND).

3.         What is the difference between the absolute threshold and the difference threshold? Is the difference threshold constant?

4.         What impact does intrinsic light (“dark light”) have on determination of an observer’s absolute threshold? Make sure un understand the theoretical implications of intrinsic “events.”

5.         Why does the graph of “ideal results” differ from the graph of “actual results” when determining the absolute threshold using the method of constant stimuli?

6.         Be able to describe a hypothetical experiment using the method of constant stimuli to determine both absolute threshold and difference threshold. What is the conventional definition of the absolute threshold using this method? What is the conventional definition of difference threshold using this method?

7.         What is a psychometric function?

8.         Whether calculating absolute or difference thresholds, what is one drawback to using the method of constant stimuli?

9.         Describe how you would determine absolute and difference thresholds using the method of limits. What are the conventional definitions of absolute and difference threshold using this method?

10.       Describe how you would determine the absolute threshold using the method of adjustment. How would you use this method to determine difference threshold?

11.       What is the staircase method and what improvement does this bring to the method of limits? What problem is inherent in using a single staircase? How is this problem solved?

12.       What did McKee’s (1981) experiment in visual velocity tell us about the need for a standard stimulus and about the observer’s perceptual behavior?

13.       What deficiency do forced-choice methods correct in the previously discussed subjective (self-report) techniques?

14.       What have forced-choice methods demonstrated regarding the nervous system?

15.       Why would different observers have different criteria? What types of things go into a person’s criterion at a given point in time?

16.       What is signal detection theory? What are the two primary benefits that SDT brings to psychophysics?

17.       What does it mean to say that SDT compares the ratio of signal-to-noise? How is this ratio determined? What is a “hit rate” and a “false alarm rate?” (And the corresponding “miss rate” and “correct reject rate”.)

18.       What is a psychophysical function? How is a psychophysical function related to psychometric functions?

19.       Why is October 22 called “Fechner Day?” (I bet you didn’t know that, did you?) This is just for fun—you can look it up on Google if you want, but you don’t have to.