Figure 3:

The weights obtained during classification have been plotted for each feature construction scenario: monadic features in (a), dyadic features in (b), statistics for monadic features in (c), and statistics for dyadic features in (d). For each feature, the y-axis represents the weight coefficients assigned by the SVM classifier in (a) and (b), and the mean and standard deviation of those weights in (c) and (d). In the monadic case, features are the single head movement angles (upward pointing triangles) and their differentials (downward pointing triangles). The dyadic feature plot contains relationships between head angle pairs (upward pointing triangles) and their differentials (downward pointing triangles).