
88 Coverbal Synchrony in Human-Machine Interaction
the corner of the mouth superiorly and posteriorly to produce a
smile, can effectively discriminate valance (pleasure) and intensity of
emotional states.
In general, a slow low- or band-pass fi lter is applied together with
a linear piecewise detrending of the time series at a 10-s basis. From
the subject’s respiration, the following features (Boiten et al., 1994) are
computed (low-pass fi ltered at 0.15 Hz): mean and standard deviation
of the fi rst derivatives (10-s time window), breathing volume, mean and
standard deviation of breathe intervals and Poincaré plots (30-s time
window each). The ...