Stimulus information and habituation of the visual event related potential and the skin conductance reaction under task-relevance conditions.
The influence of information value of visual stimuli on habituation of event related potentials (ERPs) at Fz, Cz, Pz and Oz and of the skin conductance reaction (SRC) was investigated under task-relevance condition. An improved Wiener filter was used to reduce the number of stimulus presentations to estimate an ERP. Twenty-six subjects received two times a block of 36 stimulus presentations. Half of the subjects received a stimulus with a high information value in terms of complexity and then a stimulus with a low information value. The other half of the subjects received the reversed order. Wiener filtered ERPs and SCRs were determined over ensembles of six stimulus presentations. The habituation of the P300 component was restricted to the fronto-central leads, and was delayed when compared to the results of a former study (Woestenburg, Verbaten and Slangen, 1981b) where non-signal stimuli were used. Also information effects were noticed on these fronto-central leads, but not on the SCR. This reaction habituated as in the former non-signal study. The P300 at the parieto-occipital leads showed larger amplitudes than the fronto-central P300 and these components did not habituate. At the Oz lead early waves habituated and late waves increased during ensemble 1 to 6.