Utility of a dynamic termination criterion in the ZEST adaptive threshold method

Bayesian adaptive threshold procedures may be run for a fixed number of trials, or may be stopped when the calculated confidence interval for the threshold reaches a selected limit (a dynamic termination criterion). This study used Monte-Carlo simulations to determine whether the confidence interval is a useful predictor of errors in the estimated threshold. No difference was found between the distribution of errors in a fixed trial procedure versus a dynamically terminated procedure of the same average number of trials. In addition, the width of the confidence interval failed to usefully predict observer variability arising from a shallow psychometric function slope or increased false positive response probabilities. This study suggests that dynamic termination criteria are of little use in Bayesian adaptive threshold procedures. (C) 2002 Elsevier Science Ltd. All rights reserved.