A COMPARISON OF DIFFERENT METHODS FOR ESTIMATING SINGLE-TRIAL P300 LATENCIES

Inferences from comparative analyses of reaction time and P300 latency are stronger when the various aspects of the distribution across tria ls are treated in the same way for both variables. To this end, a numb er of studies have resorted to estimation of P300 latency at the singl e-trial level. This report presents a comparative evaluation of two co mmon methods for such single-trial analysis, i.e., peak-picking and te mplate-matching. Both methods were applied to a representative set of real data, comprising different task conditions and two age groups. Re levant scoring parameters were varied: low-pass filter settings (down to 0.94 Hz) for peak-picking, template duration (250-970 msec) and use of covariance vs. correlation for template-matching, and use of a noi se-range criterion for both methods. It is concluded that peak-picking with a 3.4 Hz filter, and template-matching using covariance and temp late duration between 600 and 800 msec, are best in terms of sensitivi ty and reliability, with peak-picking surpassing template-matching. Al so, the marked increase in the number of rejected trials when the nois e-range criterion was applied resulted in unwanted modulation of behav ioral effects of task conditions and age groups.