Biology 70 -- Fall 2007 - Lecture 4

BIOLOGY 70

INTRODUCTION TO PSYCHOBIOLOGY

LECTURE 4
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Interactive Experiments on Factors Affecting Illusions

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OVERVIEW: In this lecture we discuss how the visual system enriches perception by adding the dimensions of depth, color, and motion to the canvas of visual information. This lecture will bring more psycho in our treatment of psychobiology and, although we will not be able to be as definitive in assigning specific neural networks, we will connect perceptions to the kinds of information processing which neurons can accomplish. Artists are perhaps the most astute “viewers” of the visual world. In the final part of the lecture we look a visual illusion and how artists recognize and take account of visual information processing in their works.

  1. How might the cortex signal direction of motion?

  2. What is the explanation of the waterfall effect?

  3. What is "common fate" in regard to detecting form from motion?

  4. What is the flicker-fusion rate?

  5. In the real world what are clues which the brain uses to determine depth?

  6. What are Julsez patterns and what do they show about depth perception?

  7. What property of light is responsible for color information? Under white light why does an opaque or translucent blue object appear blue? What would be the appearance of the blue object when illuminated with red light?

  8. Know the following terms related to color and color vision:
    a. trichromacy d. saturation
    b. metameric match e. simultaneous color contrast
    c. hue

  9. What is the origin of the different spectral sensitivities of the three cone pigments?

  10. What are color opponent cells?

  11. Which of the major “parallel pathways” transmits color information?

  12. How do the Young-Helmholz and Herring theories of vision differ? Are they incompatible?

  13. What is a possible explanation for Benham’s color wheel?

  14. Describe the differences between additive and subtractive color mixing. Which types of color mixing applies to (1) paint pigments, (2) stage lighting (multi spotlight), and (3) Pointalist art?

  15. How are the following factors involved in various visual illusions?
    1. illusions with explicitly known physiological origins
    2. context or association including size constancy

  16. Give examples of the visual system "making bets" or "filling in" and understand how these can lead to illusions.

  17. Distinguish between bottom-up and top-down processing.