The aim of the present study was the comparative assessment of the 4-week test-retest stabilities of the saccadic CNV (sCNV) and saccadic reaction times (SRT) during the execution of pro- and antisaccades, as well as the stability of RT during execution of two neuropsychological tests of alertness and S-R incompatibility. Prosaccades were elicited under the 200-ms gap and overlap conditions, antisaccades under the overlap condition (64 trials each). The EEG was recorded from 25 channels with a DC amplifier (MES, Munich). Data of 20 healthy participants were statistically analyzed. We found high test-retest correlations for all SRT (.76 < or = r(tt) < or = .88) and neuropsychological (.62 < or = r(tt) < or = .88) measures. For the sCNV, coefficients ranging between .58 (pro/gap) and .77 (anti/overlap) were obtained. Whereas SRT were significantly faster during the second than during the first session, group means for the saccadic CNV were stable across the sessions. Our results suggest high 4-week stability of individual differences in SRT, and moderate to good stabilities of saccadic CNV amplitudes. Our results recommend these "traitlike" measures to be used in individual differences research.

The topography of the postimperative negative variation (PINV) was analyzed in participants with high and low scores on the German version of the Schizotypal Personality Questionnaire. Scalp amplitude and Laplacian maps of the terminal contingent negative variation (tCNV) and PINV and the time course of the PINV were compared between the two groups. CNV and PINV were induced with a delayed matching-to-sample task, in which the pattern of the imperative stimulus was either clearly or ambiguous matched to one of the two diamonds simultaneously presented as a warning stimulus 4.0 s earlier. Electroencephalograms were recorded with a DC amplifier (32 channels). Negativity increased from tCNV to PINV, especially at frontal sites, and the PINV was larger under ambiguous than under clear matching conditions. Low-scoring participants showed a right-sided predominance of the PINV, which was absent in high-scoring participants. These results resemble differences in the topography of the PINV between healthy control participants and those with schizophrenia under identical experimental conditions and suggest functional differences between tCNV and PINV.

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