An evaluation of P50 paired-click methodologies.

The utility of P50 paired-click measures is limited by their unestablished reliability, unknown effects of time, and long protocol. This study measured within-session reliability, temporal course, effect of varying interpair interval (IPI), and peak definition and ratio calculation methods on P50 paired-click measures in healthy participants. Results indicate higher reliability for difference (ICC=.72) than ratio (ICC=.44) method; when P50 peaks are defined as baseline-to-peak than peak-to-peak; time-related changes; and comparable P50 paired-click measures at long (9 s) and short (3-7 s) IPIs. After controlling for time effects, P50 paired-click measures are relatively reliable within-session and are best measured using the difference method and defined as baseline-to-peak amplitude; time effects must be taken into account when measuring P50 paired-click measures in a long paradigm; and IPI can be shortened in studies with healthy samples.