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If n != m then it will not home in on the 50 % threshold. In these simple N-up/N-down staircases, you can modify either the stepsize (as you proposed) or the number of successes/failures to act as a criterion for upgrade/downgrade. A comprehensive introduction to these staircases and the effect of changing these properties can be found in this paper. The 80 ...


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It generally helps to provide some sort of specification as to how well you want to control the timing. There are 4 orders of magnitude difference between the 100 ms timing accuracy required for auditory and visual stimuli to be judged simultaneous (Zampini et al. 2005) and the 0.1 ms timing accuracy required for binaural stimuli to be judged simultaneous ...


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I guess it depends on your purpose. If you are doing the MDS for more heuristic purposes, then often two dimensions (or possibly three) will provide the greatest visual insight. Also, my sense from looking at your dimension by stress plot is that the greatest gains are attained when going from one to two dimensions, that the gain from two to three ...


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There was a special issue of the journal Perception and Psychophysics in 2001, titled Psychometric Functions and Adaptive Methods. It contains several papers relevant to your question. Klein's paper [1] references all the others and reviews what each is about. It should serve as a good starting point. An excerpt from Klein's summary: The simple ...


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It is going to mean bad things. If you can only create stimuli with a predefined non uniformly sampled set of "levels" then the the corresponding percent correct that the staircase will track will depend on the threshold of an individual observer. For example, if you can create stimuli with levels of 0, 1, 2, 3, ..., 100, 110, 130, 170, 250, 410, where for ...


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For these types of questions I really like Detection Theory: A User's Guide by Macmillan and Creelman. They consider 3 types of bias. The criterion location c is calculated relative to the zero-bias point and expressed in units of standard deviations, such that a c of 1 means the criterion is 1 standard deviation to the right of the zero-bias location and a ...



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