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PSYCH306: Sensation and Perception

Unit 2: Psychophysics   The term “psychophysics” refers to the methods and techniques that researchers use when studying sensation and perception. This field is unique in that researchers rarely have directly accessible, hard evidence with which to work. Take, for example, the following question: “Is the color I think of as green the same color that others think of as green?” The researcher will have to come up with some unique research methods to find an answer to this highly subjective question. This unit will take a close look at psychophysics and its methodologies.

Unit 2 Time Advisory
This unit should take you 10.5 hours to complete.

☐    Subunit 2.1: 3.5 hours

☐    Subunit 2.2: 3.5 hours

☐    Subunit 2.3: 3.5 hours

Unit2 Learning Outcomes
Upon successful completion of this unit, students will be able to:
- explain the basic principles of classical psychophysics; and - describe the fundamental methods of classical psychophysics.

2.1 What is Psychophysics?   - Reading: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” (PDF)
 
Instructions: Read pages 2.1 to 2.6, up to the section titled “Classic Psychophysical Methods.” NOTE: These instructions apply to subsections 2.1.1-2.1.4.
 
Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.1.1 Detection of a Stimulus   Note: The introductory reading assigned at the start of unit 2 and the reading assigned for subunit 2.1 also cover this subunit

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Basic Ideas” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Basic Ideas” (JAVA)
     
    Instructions: If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page displaying a black, white, and grey “grating.” The grating is a series of dark and light vertical bars displayed across your computer screen. Click the text link “Instructions” in the upper left corner and follow the directions. As you increase the size of the movement with the slider at the bottom of the page, it should be easier for you to detect the horizontal movement of the grating. Keep doing this until you get a good feel for the relationship between your accuracy and the degree of movement you are trying to detect.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.1.2 Discrimination of a Stimulus   Note: The introductory reading assigned at the start of unit 2 and the reading assigned for subunit 2.1 also cover this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Discrimination Threshold, or JND” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Discrimination Threshold, or JND” (JAVA)
     
    Instructions: Click the link above or the link on page #3 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Discrimination Threshold, or JND.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page displaying a black, white, and grey “grating.” The grating is a series of dark and light vertical bars displayed across your computer screen. Click the text link “Instructions” in the upper left corner and follow the directions. There are 25 trials, and please continue the experiment until the program provides your results in graphical form on the last page. You should see that your accuracy increased with the size of the difference in movement of the two gratings. This is a basic discrimination experiment.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.1.3 Psychophysical Experiments: How are they Conducted?   Note: The introductory reading assigned at the start of unit 2 and the reading assigned for subunit 2.1 also cover this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Asking Questions” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Asking Questions” (JAVA)
     
    Instructions: Click the link above or the link on page #5 of the “Chapter 2” PDF document for the embedded activity called “Interactive Illustration 2.x: Asking Questions.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page displaying a black, white, and grey “grating.” The grating is a series of dark and light vertical bars displayed across your computer screen. Click the text link “Instructions” in the upper left corner and follow the directions. As you progress through each trial, notice how your introspective feedback differs from the quantitative measurement.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.1.4 Threshold Psychophysics   Note: The introductory reading assigned at the start of unit 2 and the reading assigned for subunit 2.1 also cover this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Absolute Threshold” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Absolute Threshold” (JAVA)
     
    Instructions: Click the link above or the link on page #3 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Absolute Threshold.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page displaying a black, white, and grey “grating.” The grating is a series of dark and light vertical bars displayed across your computer screen. Click the text link “Instructions” in the upper left corner and follow the directions. There are 25 trials, and continue the experiment until the program provides your results in graphical form on the last page. You should see that your accuracy increased with the size of the movement. This is a basic detection experiment.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.2 Psychophysical Methods   Note: The introductory reading assigned at the start of unit 2 also covers this subunit

  • Reading: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” (PDF)
     
    Instructions: Read from the bottom of page 2.6, starting with the section titled “Classic Psychophysical Methods” and continuing to the section titled “Psychophysical Laws” on page 2.14.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.2.1 Method of Limits   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Limits” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Limits” (JAVA)
     
    Instructions: Click the link above or the link on page #7 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Method of Limits.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you need to make a number of settings choices. Click the text link “Instructions” in the upper left corner and follow the directions. Please be patient; psychophysical methods require many trials. You may repeat the experiment with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.2.2 Method of Constant Stimuli   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Constant Stimuli” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Constant Stimuli” (JAVA)
     
    Instructions: Click the link above or the link on page #8 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Method of Constant Stimuli.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you need to make a number of settings choices. Click the text link “Instructions” in the upper left corner and follow the directions. Please be patient; psychophysical methods require many trials. You may repeat the experiment with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.2.3 Method of Adjustment   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Adjustment” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Method of Adjustment” (JAVA)
     
    Instructions: Click the link above or the link on page #9 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Method of Adjustment.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you need to make a number of settings choices. Click the text link “Instructions” in the upper left corner and follow the directions. Please be patient; psychophysical methods require many trials. You may repeat the experiment with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.2.4 Forced Choice Techniques   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Forced Choice” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Forced Choice” (JAVA)
     
    Instructions: Click the link above. If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page that asks you to adjust the volume of your computer speakers. Follow the onscreen prompts to complete the demonstration. Please be patient; psychophysical methods require many trials. You may repeat the experiment with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.2.5 Signal Detection Theory   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x, Signal Detection Experiment” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Signal Detection Experiment” (JAVA)
     
    Instructions: Click the link above or the link on page #11 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x, Signal Detection Experiment.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page that asks you to adjust the volume of your computer speakers. Follow the onscreen prompts to complete the demonstration. Please be patient; psychophysical methods require many trials. You may repeat the experiment with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Model 2.x: Signal Detection Theory” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Model 2.x: Signal Detection Theory” (JAVA)
     
    Instructions: Click the link above or the link on page #11 of the “Chapter 2” PDF document for the embedded activity called “Interactive Model 2.x: Signal Detection Theory.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page that gives you control over the various signal detection parameters, such as the strength of the signal and noise, and the location of the decision criterion. Adjust the various settings and watch how the situation changes. This should help you better understand the basics of signal detection.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Model 2.x: Decisions in SDT” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Model 2.x: Decisions in SDT” (JAVA)
     
    Instructions: Click the link above or the link on page #12 of the “Chapter 2” PDF document for the embedded activity called “Interactive Model 2.x: Decisions in SDT.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page that gives you control over the various signal detection parameters, such as the strength of the signal and noise, and the location of the decision criterion. Adjust the various settings and watch how the decision situation changes. This should help you better understand the decision-making process in signal detection.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.3 Psychophysical Laws   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Reading: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” (PDF)
     
    Instructions: Read from page 2.14 starting with the section titled “Psychophysical Laws” through the end of the document.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.3.1 Weber’s Law   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Weber’s Law” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Weber’s Law” (JAVA)
     
    Instructions: Click the link above or the link on page #14 of the “Chapter 2” PDF document for the embedded activity called “Interactive Illustration 2.x: Weber’s Law.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page with two circles, two graphs, and a slider on the far right. Follow the directions in the PDF document to see an illustration of Weber’s Law in action.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

2.3.2 Fechner’s Law   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Fechner’s Law and JND” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 2.x: Fechner’s Law and JND” (JAVA)
     
    Instructions: Click the link above or the link on page #14 of the “Chapter 2” PDF document for the embedded activity called “Interactive Illustration 2.x: Fechner's Law and JND.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page with a graphs in the middle and a slider on the far right. Follow the directions in the PDF document to see an illustration of Fechner’s Law in action.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.3.3 Stevens’ Law   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Reading: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” (PDF)
     
    Instructions: Read from the section titled “Stevens’ Law” on page 2.15 to the end of the document.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.

2.3.4 The Law of Magnitude Estimation   Note: The introductory reading assigned at the start of unit 2 also covers this subunit.

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Magnitude Estimation” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Magnitude Estimation” (JAVA)
     
    Instructions: Click the link above or the link on page #16 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Magnitude Estimation.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you need to make a number of settings choices. Click the text link “Instructions” in the upper left corner and follow the directions. Please be patient; psychophysical methods require many trials. You may repeat the demonstration with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original from here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder. 

  • Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Magnitude Estimation 2” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 2.x: Magnitude Estimation 2” (JAVA)
     
    Instructions: Click the link above or the link on page #16 of the “Chapter 2” PDF document for the embedded activity called “Experiment 2.x: Magnitude Estimation 2.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you need to make a number of settings choices. Click the text link “Instructions” in the upper left corner and follow the directions. Please be patient; psychophysical methods require many trials. You may repeat the demonstration with different settings as many times as you like.
     
    Terms of Use: The linked material above has been reposted by the kind permission of John Krantz, and can be viewed in its original form here. Please note that this material is under copyright and cannot be reproduced in any capacity without explicit permission from the copyright holder.