LABS
Apparatus used for psychophysical experiments
Our most common lab setup is based on a design developed by Don Kelly through many years. It is a computer-controlled apparatus comprising a calibrated color CRT screen, an SRI Eyetracker, and a stimulus deflector system. The stimulus is displayed on the color CRT with spatial, temporal and color variables controlled by a computer. The subject looks at the screen while biting on a bite board attached to the apparatus in order to keep his head still. For some experiments, the bite board plus careful fixation of the subject's sight to a fixation point on the screen are sufficient. However, in many cases, involuntary eye movements introduce unacceptable artifacts. In these cases, the subject looks at the stimulus through the combined eyetracker and optical deflector system. The eyetracker registers the subject's eye movements and transmits them to the deflector system which deflects the optical image of the color display compensating for the eye's movements. The subject has a control box which encodes and transmits a variety of responses to the computer which analyzes them and affects the parameters of the stimuli to follow, according to specific programs.
The best source of information about the details of this experimental setup and the corresponding results are the works of Don Kelly, published in vision journals for the last 30 years. He was one of the most prominent scientists of the visual sciences community, and a cornerstone member of SRI's Visual Sciences Program. Chapters 3 and 7 from his book: "Visual Science and Engineering", published by Dekker in 1994, are excellent summaries of work conducted in lab setups like the one sketched above.
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Psychophysics |||
SRI Eyetracker |||
Chromaplex |||
Labs
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