Deviation limit The maximal difference (in number of trials) between the desiredĪccuracy and the actual accuracy, beyond which the level should be changed. Target accuracy The performance accuracy level to be achieved by the participant.Įxpressed as a floating point number between zero (0%, or all wrong), and (The algorithm, if uncorrected,Ĭan choose negative or values that are otherwise unsuitable for the Minimal value The smallest absolute value of step. Maximal change The largest absolute difference between consecutive steps. Positive value causes an increase in level when performance is too high,Īnd vice versa. First change The direction (positive or negative) and amount by which to change the Input Parameters Starting level The level of the IV for the first step. Trial A single stimulus-presentation to which the participant should Step-change The change in level between steps. Step A contiguous sequence of trials at a given level. DV The response from the participant (the Dependent Variable). Terminology Level The task stimulus-property being adjusted (the Independent Variable or The rules that govern the level chosen at each change. The participant with the minimal number of trials. PEST is especially efficient in obtaining a given performance level from
#Parameter elimination by sequential testing series#
A series of consecutive trials at the same Whenever the IV is changed, the accuracy is Participant's accuracy is too high, the IV's level is changed to make the Thus, PEST presents trials at a certain level of the IV, and if the Stimuli are presented until the participant responds correctly (simpleĭetection, or the correct selection from a number of options) to a given For instance, Taylor and Creelman tested participants'Ībility to detect a sound by varying its loudness until participants detectedįor a test of mental-processing speed, one might adjust the rate at which Moreįormally, a property of some signal (the independent variable) is adjusted toįind the magnitude that results in a performance of specified accuracy (theĭependent variable). It is a set of rules for adjusting the difficulty of a task to quicklyįind the point at which performance reaches a predefined level. (Journal of the Acoustical Society of America, Volume 41, Number 4, Douglas Creelman, in "PEST: Efficient Estimates on Probability Functions" The PEST algorithm is based on the procedure described by M. PEST: Parameter Estimation by Sequential Testing PEST: Parameter Estimation by Sequential Testing Introduction
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