Abstract
This paper describes how to detect the P300 component of event-related potentials (ERPs) in the consideration of individual differences. P300 appears as a result of interesting stimulus for a subject and can be used to detect its attention. In this study, the subjects were asked to choose one target word from five that were randomly presented. These methods were used for detecting P300: (1) band-pass filtering of ERP components around a central frequency (e. g., 3Hz); (2) an average of 20 single-trial responses to each stimulus; (3) subtraction of the common components in ERP responses to target and nontarget stimuli; and (4) cutting out of P300 with a trapezoidal time window. It is very important to use suitable experimental parameters for each subject to improve the rate of judgment. The experimental parameters we used: (a) central frequency of band-pass filtering; (b) the number of averaging; (c) position of trapezoidal time window; and (d) width of trapezoidal time window. The experimental results demonstrated that it is possible to construct a more practical communication aid for patients of amyotrophic lateral sclerosis when the experimental parameters are optimized for each patient.
