MONT 104S Perception and VR

College of the Holy Cross, Fall 2008

Home | | Schedule | | Assignments | | Lecture Notes Assignment 5 Due: Friday, October 17, in class Problem 1: The moon illusion Image source: http://img.blogcu.com/uploads/MesajinizVar_0605_moon_illusion_400x302.jpg In class we discussed the moon illusion, in which the moon rising on the horizon looks much bigger than it does when it is directly above us in the sky, even though the image size of the moon is the same in both cases. We discussed two possible explanations for this, one involving the perceptual phenomenon known as "size constancy" and the other involving the distortion illusions caused by relative size. a) Describe how the moon illusion might be explained by size constancy. In your answer, explain what is meant by size constancy and how Emmert's law relates to size constancy. b) Explain how the moon illusion might be explained by relative size effects. In your answer, explain what relative size illusions are (e.g. the Ebinghaus illusion) and how the moon illusion might fit into this category. Problem 2: Analyzing a research paper Download this article on the moon illusion and read it. (Note: you will need the course username and password to download the article. Enter the same username and password that you use to access solutions to homework assignments.) Write an essay analyzing the article. Your essay should be a minimum of two pages, typed, double spaced, 12 point font. Your essay should include the following: An introduction describing the question the authors are investigating with their experiments, and a summary of the background underlying the questions. A summary of the experiments they performed and the results of the experiments. A summary of the conclusions the authors drew from the results of their experiments. Your own critique of the paper. Did the results justify the conclusions? Did the authors adequately rule out other possible explanations? What still needs to be done to further investigate the questions addressed here? Problem 3: Visual Illusions In class we saw a demonstration of the Ames Window, which is a trapezoidal shaped window that looks like it is slanting back in depth. When the window is rotated, it appears to rock back and forth. You can find the demo of this at: http://www.richardgregory.org/experiments/index.htm Based on your knowledge of perspective projection, and your examination of the rotating window, explain why the window appears to change directions. Does it appear to move in the reverse direction when the narrow edge is in front or when it is in back? Use diagrams of the window and its projected image to help in your explanation. Home | | Schedule | | Assignments | | Lecture Notes Constance Royden--croyden@mathcs.holycross.edu MONT 104S, Perception and VR Date Created: January 26, 2008 Last Modified: September 19, 2008 Page Expires: September 19, 2009