PSYC 4410: Sensation & Perception
Fall 2014
Experiment #3
Key dates:
• Nov 6th (Thursday): Experiment #3 assignment posted on LMS
• Nov 17th (Monday): Data collection for Experiment #3
• Nov 24th (Monday): Experiment #3 reports due
Possible topics for Experiment #3:
• Motion perception: motion aftereffects, induced motion, apparent motion, the correspondence problem, biological motion perception, kinetic depth effect, the perception of 3D shape
• Perception of color
• Perception of depth or size
• Create or modify a perceptual illusion. To get started, consider checking out web sites on illusions or looking at a book of illusions. This will give you a better sense of the different kinds of illusions that have been explored, and what they can reveal about perception.
Regardless of whether you create an entirely new illusion or modify an existing illusion, try to design your experiment so that the results lead to a better understanding of how the illusion works. For example, you might consider testing ways in which an existing illusion could be changed before the illusion no longer works. In your report, be sure to explain what the illusion reveals about the visual system under normal, everyday (non-illusory) conditions. You might consider discussing the assumptions or constraints in normal perception that your illusion highlights. Alternatively, you might explain how your illusion arises as a result of properties of neurons in the visual brain.
Important suggestions: Please read these carefully before designing your experiment.
• Try to design your experiment to test competing hypotheses. If you do this correctly, you should be able to state in the introduction of your report “If Hypothesis A is correct, it is expected that... Alternatively, if Hypothesis B is correct, it is expected that...”
• Be clever! Keep in mind that your subjects are classmates who may be able to guess the hypotheses of your experiment. Try to design your experiment in such a way that subjects’ responses cannot be biased by their knowledge of the hypotheses.
• You may search the web for ideas, but you must cite your source if you decide to use a stimulus created by someone else. Before you decide to use someone else’s stimulus, consider how the stimulus could be modified to test something new.
• Consider my comments on the first two experiments.
Data collection:
• The entire class period on Monday, Nov 17th will be set aside for data collection, using other people in the class as participants. Expect to have approximately 45 minutes of class time to gather data. You want data from as many participants as possible. So keep your experiment short and simple. Practice running your experiment before class to make sure that there are no problems.

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Your experiment must be run in class. If you come to class without an experiment or if you skip class, then you may collect data outside of class. However, you will be penalized two points (out of ten) on your report.

Ethical considerations:
• Take all necessary precautions to make sure that there are no risks associated with participating in your experiment. This includes the making sure that germs cannot be spread from one participant to another.
• Respect the privacy of your participants. Data collection should be completely anonymous.
Identify participants by number