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Codification of the orienting movements within mesencephalic structures| old_uid | 8742 |
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| title | Codification of the orienting movements within mesencephalic structures |
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| start_date | 2010/05/21 |
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| schedule | 14h30 |
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| online | no |
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| details | invité par Laurent Goffart |
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| summary | Widespread use of psychophysical protocols outside of the laboratory is hindered by the requirement of large numbers of judgments by observers. Additionally, inference from detection and discrimination experiments about the underlying response functions or mechanisms is indirect. For example, accurate estimates of contrast sensitivity require hundreds of trials over several spatial frequencies and the results inform us only about the limits of vision and little about perception. I will discuss the suprathreshold procedure of difference scaling which requires observers to compare intervals between pairs of pairs of stimuli (or quadruples) leading to a scale of suprathreshold perceptual differences. The method has recently been reformulated within a signal detection model for which scale values are estimated by maximum likelihood (Maloney and Yang, 2003) and has been demonstrated to be flexible enough for measuring perceptual scales in diverse circumstances (Obein et al, 2004; Charrier et al. 2007; Rhodes et al., 2007; Knoblauch and Maloney, 2008). A modification of the procedure to use triples rather than quadruples of stimuli on each trial renders the technique more efficient and the judgments easier to make. For example, I will show how to obtain an estimate of the human contrast response function in 5 minutes and will demonstrate the use of this approach to explore the effects of retinal pathology on contrast and response gain. |
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| responsibles | Riehle |
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