Ponzo Experiment Instructor's Page



Ponzo Experiment

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Introduction Design Data Analysis References
Introduction
The Ponzo illusion is one of a set of "geometrical"illusions that produce misjudgment of relative line length. The effect is illustrated below. Once you have adjusted the bottom line to be the same apparent length as the upper line, you can click the button to erase or reinstate the "converging lines" background. When the background is removed you will see that you made the bottom line longer than the top line. « Return to Top»
Design
The experiment contrasts judgments on five control trials with five experimental trials. For the experimental trials, the "converging lines" background that induces misjudgment of length is present. On control trials, the background is plain. The dependent variable is the difference in the lengths of the upper and lower lines measured in pixels. A positive number indicates that the lower line has been drawn to be longer than the upper line. A negative number means the lower line was drawn shorter than the upper line. « Return to Top»
Data Analysis
The data for the experimental and control conditions can be compared to see how much perceptual distortion was introduced by the converging lines. A bar graph with standard errors can be used to display the data. This graph may reveal such strong differences that there will be no need to conduct a significance test. If the research participants in the Ponzo experiment have also completed the Poggendorff and Muleller-Lyer experiments, one could correlate errors on the three illusions to see if there is a relationship. That is, do people who experience a strong Ponzo effect also experience strong Mueller-Lyer and Poggendorff effects? « Return to Top»
References
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Last revised:November 01, 2003 07:01:31 PM Copyright© 1995 The University of Mississippi. All rights reserved. Questions about this page?PsychExps