background
software (purpose, applet, software)
instructor's resources
selected publications

Background

The illusion of percieved motion occurs when two successive stimuli are shown seperated by a brief flash. The percieved appearance is of one stimuli moving from the location of the first stimuli to the second. An everyday example of this phenomenon is motion picture films, which string together thousands of static images to cause the appearance of motion.

This phenomenon is highly dependent on the length of the flash (pause between the first and second stimuli) as well as the distance between the two stimuli. The farther the distance between the stimuli, the longer the flash must be to allow the appearance of motion, as if time must be allowed for the stimuli to travel from its original location to the next. If the pause before the second stimuli is too long or too short, the phenomenon dissappears. Not only that, but when more stimuli are added to the environment, complications occur in the percieved phenomenon of which stimuli translates into which other stimuli, especially if there are differences in color, shape, or a odd number of stimuli.

Purpose of Our Software

This program lets users create dynamic displays by placing objects on the left and right screens, and then flipping between them. The movies below illusrate the dynamic nature of the program, as well as how the model attempts to predict which objects will correspond.

Double-click on each movie to play a short clip.

The movie on the left illusrates how two alternating displays can give the illusion of apparent motion as the eye seeks to make correspondences between two displays. The movie on the right illustrates how the model attempts to assign links between objects in the two displays. We turn ghosting on, which helps see correspondences in space.

Instructor's Resources

Here are some instructor resources for Apparent Motion. The basic goal of the unit is to allow students to discover the relationship between experimentation and model-based explanations for the observed phenomenon. In this case data collection is easy: students simply use their own perceptions as data collection. The built-in model makes clear connections between the student's reported phenomenology and the model's current prediction for what they should see.

• Apparent Motion Introductory Activity. This gets students thinking about how they should approach this program.
• Apparent Motion Writing Assignment. This asks students to report on the simulation they have explored.
• Apparent Motion Reflection Paper. This taps student understanding of the basic concepts covered in this unit, including the relation between data collection and modeling.
• Apparent Motion Generalization Paper. This looks for generalization to broader contexts in which modeling might apply.

Java Applet

Applet. Doesn't allow loading or saving.

Software

Windows executable
Application download

Introductory Movie Introduces features of software and walks through an example experiment.
Modeling Introduction Movie Demonstrates the modeling feature of the software, which predictes visual/cognitive links between stimuli during percieved motion.

Selected Publications on Apparent Motion

1. Time Course of Comparison. Goldstone, R.L., Medin, D. (1994). Journal of Experimental Psychology: Learning, Memory, and Cognition, 20: 29-50. (pdf).
   One proposed model on the subject.
2. The How and Why of What Went Where in Apparent Motion: Modeling Solutions to the Motion Correspondence Problem. Dawson, M.R. (1991). Psychological Review, 98: 561- 603. (pdf).
   Long but comprehensive review of apparent motion and corresponding models.