Fig. 2.

MEG data pursuit artefact removal and subject exclusion.

The topoplot on the top left is an average over 0–200 ms of the first eight subjects' MEG data and both conditions. It shows the extent of the pursuit artefact (the inverted U-shaped blue band across the anterior regions). The four topoplots at the bottom show individual subject data, averaged over 0–200 ms of the Smooth condition, after pursuit artefact removal (units are in femtoTesla). Pursuit artefact removal seemed successful on inspection of most subjects' topoplots: two examples are the pair on the left. However, three subjects still appeared to be compounded by pursuit artefacts — two are shown on the right. The graph on the top right plots the first two principal components of individual subjects' MEG data, averaged over conditions. The three subjects on the bottom left were subsequently treated as outliers and excluded from the MEG grand average.