Fast psychophysical procedures for clinical testing.
INTRODUCTION: Psychophysical methods are used in clinical settings to obtain estimates of visual performance. Such methods should be fast and accurate, yet robust to the corrupting effects of false responses. METHODS: In this paper, we develop these concepts and investigate the efficiency of two maximum likelihood methods (bestPEST and ZEST) for use in clinical applications. The performance of both methods will depend on whether a criterion-free paradigm (alternate forced choice) is adopted. RESULTS: Our data show that the number of trials needed to obtain reliable thresholds with a yes/no paradigm can be as few as six to eight, provided no false responses are given within the first few trials. In addition, we show that the reliability and short-term variability of the endpoint of the methods is compatible with clinical applications. CONCLUSION: We show that a yes/no maximum likelihood method using a small number of presentations will yield reliable and accurate estimates of threshold in a clinical setting.