Table 6: Elements of feature vectors.

Speech-based feature Face orientation feature (a) (b) (c) (a) (b) (c) Length until input utterance ◯ ◯ ◯ continuous () ◯ ◯ Length of silence ◯ ◯ ◯ ◯ ◯ Length of filler ◯ ◯ ◯ ◯ ◯ Length of filled pause ◯ discrete () ◯