An efficient adaptive procedure for psychophysical discrimination experiments
article
We present an adaptive procedure to conduct psychophysical discrimination experiments. In a discrimination experiment, an observer senses (sees, hears, feels, etc.) two stimuli (separated in space or time) and is asked to order these stimuli with respect to a particular parameter (say,s). Under the usual assumption of a locally linear internal representation ofs, perturbed by additive Gaussian noise, the probabilityP(s 2)—of judging test stimuluss 2 “larger” than a reference stimuluss 1—is an error function (a cumulative normal distribution). Such an error function,Erf [(s 2μ)/σ], is parametrized by two parameters: μand σ. The parameter μ is the value for whichP(s 2) = 50% and is related to possible bias effects in the internal representation of the observer. The parameter σ is √2 times the standard deviation of the noise distribution and is generally called thediscrimination threshold. In this paper, we present (1) an algorithm to estimate μ and σ given the data generated by such an observer, (2) an analysis of the efficiency of a stimulus presentation with respect to the estimation of μ and σ , and (3) a method that controls the specific choice of stimulus values during an experiment so that an optimal estimation of μ and σ is obtained.
TNO Identifier
8624
Source
Behavior Research Methods, Instruments & Computers, pp. 556-652.
Pages
556-652
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