Psychophysics: The Fundamentals

By George A. Gescheider | Go to book overview
Save to active project

3
The Classical Psychophysical Methods

The experiments described in Chapters 1 and 2 are examples of how psychophysics has been used to determine the sensitivity of perceptual systems to environmental stimuli. In Chapter 3, the specific methods for measuring sensitivity are discussed in detail.

Presenting a stimulus to observers and asking them to report whether or not they perceive it is the basic procedure for measuring thresholds. Biological systems are not fixed, however, but rather are variable in their reaction. Therefore, when an observer is presented on several occasions with the same stimulus, he or she is likely to respond yes on some trials and no on other trials. Thus, the threshold cannot be defined as the stimulus value below which detection never occurs and above which detection always occurs. The concept of the threshold has obviously been, and still is, useful, since it affords a technique for quantifying the sensitivity of sensory systems. But since reactions to stimuli are variable, the threshold must be specified as a statistical value. Typically, the threshold has been defined as the stimulus value which is perceptible in 50% of the trials.

Fechner recognized the statistical nature of thresholds and the necessary methodological consequences. Psychologists are indebted to him for developing three methods of threshold measurement: the methods of constant stimuli, limits, and adjustment. Each of these methods consists of an experimental procedure and a mathematical treatment of data. These extremely valuable techniques for obtaining absolute and difference thresholds (RL's and DL's) are still used today.

-45-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited page

Bookmark this page
Psychophysics: The Fundamentals
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen
/ 440

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?