Week 10: Homework 3 - Making Movies

This week you'll use applications contained in the "MotionStuff" folder in the Honors 185 folder in the Electronic Classroom. First: change the colors to 256 using the application in the folder ("Set to 256 color mode"). Log-in and copy that folder to the local workspace of your computer (this exercise must be done in the EC).

1. Apparent Motion. Open the application called "Apparent Motion" and read the background information. Then create different apparent motion sequences using the buttons on the hypercard page, viewing each sequence by clicking on the "Begin" button. (The sequence will continue until you click the mouse again.). Create conditions to test and answer the following questions:

• with the displacement set at 50, what is the maximum delay you can establish and still see good apparent motion with the "same shape, same orientation" stimulus? Repeat the exercise with the displacement set to 100 and then to 200.
• using the 50 displacement and delay of 10, what is the consequence of using the same shape but different orientations? what do you see?
• what is the consequence of using the same shape but different size? what do you see?
• how about different shapes?
• Quit this application and go to question 2 -

2. Form and motion. Open the application called "Form & Motion" and select help under the file menu to get instructions about details of using this file and changing variables.

• compare the effects of reducing dot correlations (1.00, 0.75, 0.35) and reducing the number of dots in the object (125, 50, 10) for the sphere. Describe how these two manipulations affect your perception of the moving shape. Which degrades your perception of shape more, reducing correlation or reducing dot number?
• explore other shapes and conditions, to get a feel for how structure from motion is affected by stationary, random and random motion background dots.
• Quit this application and go to question 3

3. MAE. Open the file called "Illusions & Aftereffects" and, again, use "Help" under the file menu to learn how to navigate and change variables.

• using the "motion" option under the aftereffects menu, measure the duration of the motion aftereffect (MAE). To do this, you will stare at the little horizontal bar midway between the two movings sheets of contours, always looking at this bar. After about 90 sec, the motion stops and the bars are stationary. But they will appear to move: that's the MAE. You are to measure the duration of the MAE by looking at the second hand on the classroom clock quickly as soon as the motion stops, then returning your fixation to the fixation bar. As soon as the last traces of the MAE have faded, look back at the clock and see how long the MAE lasted; write this down. You are to repeat this procedure following monocular adaptation (adapt with one eye closed throughout the entire adaptation period) and binocular adaptation (adapt with both eyes open). Following monocular adaptation, look at the "test" pattern using the same eye you adapted, with the other one still closed. Next repeat this monocular adaptation, only now test with the unadapted eye (i.e., for test, open the previously closed eye and close the previously open eye). Following binocular adaptaiton, test with both eyes.

Your answers and data for all these questions should be turned in by the end of the week (Friday March 19).