Loading...

PSYCH306: Sensation and Perception

Unit 3: The Visual System: Sensory Mechanisms   Earlier in this course, we spoke generally about different sense organs and the ways in which researchers can test them. We will now take a closer look at one of the most important sensory systems: vision. In its simplest terms, the eye translates light information into the complex pictures we see. The visual system includes the structures and processes that underlie our interaction with much of the world around us. Under normal circumstances, most of us consider vision our primary sense modality. With this in mind, we will first discuss the reception of visual information (sensation). The subsequent unit will cover how we use visual information once it has been received (perception).

Unit 3 Time Advisory
This unit should take you 25.5 hours to complete.

☐    Subunit 3.1: 3 hours

☐    Subunit 3.2: 2.5 hours

☐    Subunit 3.3: 3.5 hours

☐    Subunit 3.4: 2 hours

☐    Subunit 3.5: 2 hours

☐    Subunit 3.6: 3 hours

☐    Subunit 3.7: 3.5 hours

☐    Subunit 3.8: 3 hours

☐    Subunit 3.9: 3 hours

Unit3 Learning Outcomes
Upon successful completion of this unit, students will be able to:

  • explain the basic properties of the visual stimulus (light);
  • explain the important visual sensory structures and their function(s);
  • identify and describe the differences between visual sensation under low and normal light intensity levels; and
  • identify the basic visual sensory pathways in the central nervous system.

3.1 The Visual Stimulus: Properties of Light   3.1.1 What is Light?: Light as Both Wave and Particle   - Web Media: YouTube: Derek Owens’ “Physical Science 7.3a – The Nature of Light” Link: YouTube: Derek Owens’ “Physical Science 7.3a – The Nature of Light (YouTube)

 Instructions: Click the link above to navigate to YouTube and start
the video. This will introduce you to what light is and how it is
measured.  

 Watching this video should take approximately 5 minutes.  
    
 Terms of Use: The linked material above has been reposted by the
kind permission of Derek Owens  through his
[website](http://www.derekowens.com/1011/index.php) and can be
viewed in its original form
[here](http://www.youtube.com/watch?v=Puzw9T-Do9s). Please note that
this material is under copyright and cannot be reproduced in any
capacity without explicit permission from the copyright holder.
  • Web Media: YouTube: Derek Owens’ “Physical Science 7.3b – Light Waves Part 1” Link: YouTube: Derek Owens’ “Physical Science 7.3b – Light Waves Part 1 (YouTube)

    Instructions: Click the link above to navigate to YouTube and start the video. It is very important that you understand the wave properties of light and other types of electromagnetic energy.

    Watching this video should take approximately 10 minutes.
     
    Terms of Use: The linked material above has been reposted by the kind permission of Derek Owens through his website 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.

  • Web Media: YouTube: Derek Owens’ “Physical Science 7.3c – Light Waves Part 2” Link: YouTube: Derek Owens’ “Physical Science 7.3c – Light Waves Part 2 (YouTube)

    Instructions: Click the link above to navigate to YouTube and start the video. Be sure you understand how light waves are a “disturbance” in the surrounding energy.

    Watching this video should take approximately 5 minutes.
     
    Terms of Use: The linked material above has been reposted by the kind permission of Derek Owens through his website 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.

  • Web Media: YouTube: Derek Owens’ “Physical Science 7.3d – Is Light a Particle?” Link: YouTube: Derek Owens’ “Physical Science 7.3d – Is Light a Particle?” (YouTube)

    Instructions: Click the link above to navigate to YouTube and start the video. Is light a wave or a particle? This video introduces you to the “controversy.”

    Watching this video should take approximately 6 minutes.
     
    Terms of Use: The linked material above has been reposted by the kind permission of Derek Owens through his website 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.

  • Web Media: YouTube: Derek Owens’ “Physical Science 7.3e – The Double Slit Experiment” Link: YouTube: Derek Owens’ “Physical Science 7.3e – The Double Slit Experiment (YouTube)

    Instructions: Click the link above to navigate to YouTube and start the video. This video describes how light operates at a subatomic level.

    Watching this video should take approximately 11 minutes.
     
    Terms of Use: The linked material above has been reposted by the kind permission of Derek Owens through his website 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..

3.1.2 Photons   - Web Media: YouTube: Cassiopeia Project’s “Photon” Link: YouTube: Cassiopeia Project’s “Photon (YouTube)
 
Also available in:
iTunes U

[Quicktime](http://www.cassiopeiaproject.com/ViewClip2.php?type=mp4&track_number=9&Tape_Name=Standard)  
    
 Instructions: Click the link above to navigate to YouTube and start
the video. Photons are the “carriers” of electromagnetism.  

 Watching this video should take approximately 1 minute.  
    
 Terms of Use: This video has been available in the public domain.

3.1.3 Wavelength   - Assignment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 3.x: The Basics of Waves” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Experiment 3.x: The Basics of Waves” (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 illustrating a basic waveform. Use the sliders at the bottom of the page to increase or decrease the intensity and the frequency. Clicking the “Show Intensity” or “Show Wavelength” buttons will highlight those quantities. This demonstration will provide more detailed information about how we measure light.
 
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.

3.1.4 What is the Range of Light?   - Web Media: YouTube: “The Electromagnetic Spectrum” Link: YouTube: “The Electromagnetic Spectrum” (YouTube)
 
Instructions: Click the link above to navigate to YouTube and start the video. Be sure you understand that visible light is just a small “slice” of the electromagnetic spectrum.

 Watching this video should take approximately 3 minutes.  
    
 Terms of Use: Please respect the copyright and terms of use
included on the above webpage.
  • Reading: NASA’s “The Electromagnetic Spectrum: Visible Light Waves” Link: NASA’s “The Electromagnetic Spectrum: Visible Light Waves” (HTML)
     
    Instructions: Click the link above to navigate to the web page and read the main text.
     
    Terms of Use: Please respect the copyright and terms of use included on the above webpage.

3.1.5 Range of Light: What Can Others See?   - Reading: eyes-and-vision.com’s “How Animals See the World” Link: eyes-and-vision.com’s “How Animals See the World” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text. This will provide information about how other animals experience the world visually.
 
Terms of Use: Please respect the copyright and terms of use included on the above webpage.

  • Reading: webexhibit.org’s “Causes of Color: What colors do animals see? (speculation)” Link: webexhibit.org’s “Causes of Color: What colors do animals see? (speculation)” (HTML)
     
    Instructions: Click the link above to navigate to the web page and read the main text. Take particular note of the word “speculation” in the title of this resource. There is no way we can directly experience what other animals sense or perceive.
     
    Terms of Use: Please respect the copyright and terms of use included on the above webpage.

3.1.6 What Changes Light?   - Web Media: Molecular Expressions’ “Basic Electromagnetic Wave Properties” Link: Molecular Expressions’ “Basic Electromagnetic Wave Properties” (HTML)
 
Instructions: Click the link above to navigate to the website. In the animation, use the sliders to see the relationship between frequency, wavelength, color, and intensity. Think about how changes in these quantities change your perception of the colors.
 
Terms of Use: Please respect the copyright and terms of use included on the above webpage.

3.2 The Eye: Capturing and Focusing Light   - 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 “The Eye” near the bottom of page 3.3 through “Comparing Eyes” on page 3.7. NOTE: This document is in a continuous state of updating. Please ignore the internal notes, such as “[need illustration here],” for example. Most of the referenced figures are included at the end of the document; it is okay if not all the figures are available.
 
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.

  • Assessment: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 3.x: Basic Focusing” (JAVA)
     
    Instructions: Click the link above or the link on page #4 of the “Chapter 3” PDF document for the embedded activity called “Interactive Illustration 3.x: Basic Focusing.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you can demonstrate how the eye captures and focuses light. 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.

3.3 Anatomy of a Human Eye   3.3.1 Basic Structures and Functions   - Web Media: LensShopper.com’s “Anatomy of the Eye” Link: LensShopper.com’s “Anatomy of the Eye” (Adobe Flash and HTML)
 
Instructions: Click the link above to navigate to the web page. On the diagram of the human eye, click each labeled structure and, in turn, read the description.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.3.2 What is the Blind Spot?   - Reading: Bryn Mawr College: Serendip’s “Seeing More Than Your Eye Does” Link: Bryn Mawr College: Serendip’s “Seeing More Than Your Eye Does” (HTML)
 
Instructions: Click the link above to navigate to the web page. Read the main text and follow the directions to find your blind spot. Continue through the five (5) links in the table of contents to see additional demonstrations.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.4 Diseases of the Eye   3.4.1 Glaucoma   - Reading: All About Vision’s “Glaucoma” Link: All About Vision’s “Glaucoma” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text about the disease called glaucoma.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.4.2 Cataracts   - Reading: All About Vision’s “Cataracts” Link: All About Vision’s “Cataracts” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.4.3 Macular Degeneration   - Reading: All About Vision’s “Macular Degeneration” Link: All About Vision’s “Macular Degeneration” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.5 Optics   3.5.1 Visual Angle   - Reading: Massachusetts Institute of Technology: John Gabrieli’s Introduction to Psychology: “Lecture 5: Vision I” Link: Massachusetts Institute of Technology: John Gabrieli’s Introduction to Psychology“Lecture 5: Vision I” (MP4)
 
Instructions: Watch this lecture to learn about human perceptual abilities and how the neural substrates of vision are organized in the brain. When you have finished watching the lecture, read the lecture notes for Section 1 (PDF) and Section 2 (PDF) to review the presentation.
 
Watching this lecture and reading the lecture notes should take approximately 2 hours and 45 minutes.
 
Terms of Use: This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. It is attributed to John Gabrieli, and the original version can be found here.

3.5.2 Optical Power and the Accommodation of the Eyes   - Reading: The Physics Classroom’s “The Eye” Link: The Physics Classroom’s “The Eye” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text. It is important to understand how the lenses in our eyes change in response to, or “accommodate,” various visual stimuli and general visual conditions.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.6 The Retina   3.6.1 Rods and Cones   - Web Media: Pearson Education’s “LIVE!Psych: A Tour Through the Human Eye” Link: Pearson Education’s “LIVE!Psych: A Tour Through the Human Eye” (Shockwave)
 
Instructions: Click the link above to navigate to the web page. The animation has eight (8) parts. You may skip directly to part #5 and watch parts #5 – #8. Alternatively, watch all eight (8) parts for an excellent review of the structure of the eye.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.6.2 Light and Color Vision   - Reading: Scholarpedia: Karen DeValois and Michael Webster’s “Color Vision” Link: Scholarpedia: Karen DeValois and Michael Webster’s “Color Vision” (HTML)
 
Instructions: Read this article to learn about the factors involved in color vision. Note the various stimuli needed for color vision, trichromatic and opponency theories for spectral and hue discrimination, and spatial and temporal factors involved in visual acuity and color determination.
 
Reading this article should take approximately 1 hour.
 
Terms of Use: This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. It is attributed to Karen DeValois and Michael Webster, and the original version can be found here.

3.7 Transduction of Visual Information   3.7.1 Conversion of Light Energy   - Reading: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Photoreceptors” Link: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’ “Photoreceptors” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text. Follow all the links on the page to read about the details of this process. NOTE: This reading applies to subsections 3.7.1-3.7.4.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.7.2 Photon Absorption   Note: The reading and assignments beneath subunit 3.7.1 cover this subunit. Pay particular attention to the information at the target of the link on the right titled cascade of chemical reactions in these photoreceptors.”

3.7.3 Electrical Response of the Photoreceptors   Note: The reading and assignments beneath subunit 3.7.1 cover this subunit. The figure at the bottom of the main web page describes this process.

3.7.4 Rhodopsin   Note: The reading and assignments beneath subunit 3.7.1 cover this subunit. 

  • Reading: Discovery Health’s “How Vision Works: Perceiving Light” Link: Discovery Health’s “How Vision Works: Perceiving Light” (HTML and Quicktime)
     
    Instructions: Click the link above to navigate to the web page and read the main text.
     
    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.8 Light and Dark Adaptation   3.8.1 Time to Adaptation: Gradual Processing   - 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 “Adaptation in General” on page 4.8 to “Acuity” on page 4.10. NOTE: This document is in a continuous state of updating. Please ignore the internal notes, such as “[need illustration here],” for example. Most of the referenced figures are included at the end of the document; it is okay if not all the figures are available. ADDITIONAL NOTE: This reading applies to subsections 3.8.1-3.8.3.
 
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 Illustration 4.x: Dark/Light Adaptation” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 4.x: Dark/Light Adaptation” (JAVA)
     
    Instructions: Click the link above or the link on page #8 of the “Chapter 4” PDF document for the embedded activity called “Interactive Illustration 4.x: Dark/Light Adaptation.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you can demonstrate how the eye adapts to light and dark environments. Follow the directions in the text. NOTE: This assignment applies to subsections 3.8.1-3.8.3.
     
    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 Illustration 4.x: Dark Adaptation Curve” Link: Hanover College: Professor John Krantz’s “Experiencing Sensation and Perception: Interactive Illustration 4.x: Dark Adaptation Curve” (JAVA)
     
    Instructions: Click the link above or the link on page #10 of the “Chapter 4” PDF document for the embedded activity called “Interactive Illustration 4.x: Dark Adaptation Curve.” If you have installed the JAVA plug-in (see page #2 of this course), clicking the embedded link will open a page where you can demonstrate how the eye adapts to dark environments. Follow the directions in the text. NOTE: This assignment applies to subsections 3.8.1-3.8.3.
     
    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.

3.8.2 Importance of Rods and Cones   Note: The reading and assignments beneath subunit 3.8.1 cover this subunit. See especially the section titled The Duplex Theory of Vision,” which begins on page #4. This explains how our color vision and night vision require two different receptor systems.

3.8.3 The Retina in Light and Dark Adaptation   Note: The reading and assignments beneath subunit 3.8.1 cover this subunit. See Dark and Light Adaptation, starting on page #7 for information on how rods and cones respond to changes in overall light levels.

3.9 Visual Pathways in the Central Nervous System: How Does the Information Get to the Brain and Where Does it Go?   3.9.1 Photoreceptor Signals   - Reading: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Photoreceptors” Link: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Photoreceptors” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text. It is important that you take the time to follow all the links on this and the subsequent pages to get a clear understanding of these processes.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.9.2 Retinal Ganglion Cells   - Web Media: Sumanas, Inc.’s “Receptive Fields in the Retina” Link: Sumanas, Inc.’s “Receptive Fields in the Retina” (Adobe Flash)
 
Instructions: Click the link above to navigate to the web page. Choose the “Narrated” or “Step-Through” link to view the animation.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

  • Reading: Bryn Mawr College: Bryn Mawr College: Serendip’s “Seeing More than Your Eye Does” Link: Bryn Mawr College: Serendip’s “Seeing More than Your Eye Does” (HTML)
     
    Instructions: Click the link above to navigate to the web page. Read the main text and follow the directions to find your blind spot. Continue through the five (5) links in the table of contents to see additional demonstrations.
     
    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.9.3 Parallel Pathways and the Lateral Geniculate Nucleus (LGN)   - Reading: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Targets of the Optic Nerve” Link: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Targets of the Optic Nerve” (HTML)
 
Instructions: Click the link above to navigate to the web page and read the main text. It is important that you take the time to follow all the links on this and the subsequent pages to get a clear understanding of these processes.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

  • Reading: Institute of Structural Biology and Biophysics’ “To Make Thousand Colors Out of Three Receptors - How Color Vision Works” Link: Institute of Structural Biology and Biophysics’ “To Make Thousand Colors Out of Three Receptors - How Color Vision Works (HTML)
     
    Instructions: Click the link above to navigate to the web page and read the main text.
     
    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

  • Reading: Investigative Opthalmology and Visual Science: Peter Gouras’ “Color Opponency from Fovea to Striate Cortex” Link: Investigative Opthalmology and Visual Science: Peter Gouras’ “Color Opponency from Fovea to Striate Cortex” (PDF)

    Instructions: Read the article in its entirety. Note that in the frame on the right of the page, there is a link to open the article as a PDF-only page.

    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

  • Web Media: Sumanas, Inc.’s “Visual Pathways in the Human Brain” Link: Sumanas, Inc.’s “Visual Pathways in the Human Brain” (Adobe Flash)
     
    Instructions: Click the link above to navigate to the web page. Choose the “Narrated” or “Step-Through” link to view the animation.
     
    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.9.4 The Primary Visual Cortex (V1)   - Reading: University of Utah, John Moran Eye Center: Matthew Schmolesky’s “Primary Visual Cortex” Link: University of Utah, John Moran Eye Center: Matthew Schmolesky’s “Primary Visual Cortex” (HTML)
 
Instructions: Click the link above to navigate to the web page. Scroll down the page until you find “Part IX: The Primary Visual Cortex.” Use the menu links to read each of the twelve (12) sections in full.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

  • Reading: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Receptive Fields, from the Retina to the Cortex” Link: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “Receptive Fields, from the Retina to the Cortex” (HTML)
     
    Instructions: Click the link above to navigate to the web page and read to the end of the page. It is important that you take the time to follow all the links on this and the subsequent pages to get a clear understanding of these processes.
     
    Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.

3.9.5 Secondary Visual Areas   - Reading: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “The Various Visual Cortexes” Link: Canadian Institutes of Health Research: Institute of Neurosciences, Mental Health and Addiction’s “The Various Visual Cortexes” (HTML)
 
Instructions: Click the link above to navigate to the web page and read from Section #3 to the end of the page. It is important that you take the time to follow all the links on this and the subsequent pages to get a clear understanding of these processes.
 
Terms of Use: Please respect the copyright and terms of use included on the above document and webpage.