Visual mismatch negativity was identified if, within the 100–300-ms latency range, deviant-minus-standard amplitude difference was different from zero at least at five subsequent points at any occipital location [for reviews of the characteristics of the range and surface distribution of the vMMN, see Czigler (2007) and Kimura (2011)]. In this
way, we identified an earlier (112–120 ms) and a later (284–292 ms) range of the difference potentials. At six electrode locations (PO3, POz, PO4, O1, Oz, and O2) as regions of interest, the average amplitude values of these epochs were calculated, and entered into anovas with factors of probability (deviant or standard), anteriority (parieto-occipital or occipital), and laterality (left, midline, or right). We compared, at the same electrode locations, the peak latencies and scalp distributions of the exogenous components and the difference potentials. Note that, Ceritinib research buy at lower half-field stimulation, the C1 and C3 components are positive and the C2 component is negative. Investigation of the relationship between a negative component and the vMMN is relevant,
because it is important to separate the refractoriness/habituation of an exogenous activity from vMMN. In this context, the similar analysis of the positive components (C1 and C3) is less important, Protein Tyrosine Kinase inhibitor because reduced exogenous positivities elicited by the deviant stimuli cannot be expected (in the case of stimulus-specific refractoriness/habituation, LY294002 amplitude reduction is expected, i.e. positive deviant-minus-standard difference). Peak latencies were measured at the maxima of the components. The distributions of the difference potential and the C2 component were compared with vector-scaled amplitude values (McCarthy & Wood, 1985). Where appropriate, Greenhouse–Geisser correction was applied. Effect size was characterised as partial eta-squared (η2). Post
hoc analyses were performed with Tukey’s HSD test. In the reported effects, the alpha level was at least 0.05. Participants avoided the red ship with a frequency of 82% (standard error of the mean, 1.53%), and caught the green ship with a frequency of 83% (standard error of the mean, 1.05%). This difference was not significant. There was no also difference in performance between the random and symmetric standard conditions. Figure 2 shows the ERPs elicited by the symmetric (A) and random (B) stimuli, as both standards and deviants, and also the deviant-minus-standard difference potentials. The stimuli elicited a positive–negative–positive (C1–C2–C3) set of pattern-specific exogenous components (Jeffreys & Axford, 1972). Table 1 shows the latency values of the exogenous components, and Fig. 3 shows the scalp distribution of the C1, C2 and C3 components and the difference surface distributions.