Statistical detection of individual evoked responses: an evaluation of Woody's adaptive filter.

The practical performance of the adaptive filter developed by Woody (1967) and Harris and Woody (1969) is assessed in terms of its ability to distinguish evoked responses from the background EEG. It is concluded that selection of good initial template, in this case the Averaged ER, renders iterations beyond the first doubtful validity in the majority of subjects. It is stressed that where iterations are pursued care should be taken over the choice of a suitable statistic to index the process. Finally, given the efficacy of the cavariance function in detecting the grosser features of ER morphology in individual responses, a single trial approach to the analysis of ERs is recommended.