Assessing Postural Control for Affect Recognition Using Video and Force Plates

Postural control is a dynamical process that has been extensively studied in motor control research. Recent experimental work shows a direct impact of affects on human balance. However, few studies on the automatic recognition of affects in full body expressions consider balance variables such as center of gravity displacements. Force plates enable the capture of balance variables with high precision. Automatic video extraction of the center of gravity is a basic alternative, which can be easily accessible for a wide range of public applications. This paper presents a comparison of balance variables extracted from the force plate and video processing. These variables are used to capture the bodily expressions of participants in a public speaking task designed to elicit stress. Results show that the variability of the center of gravity displacements from the force plate and video are related to negative emotions and situation appraisals. The power spectrum density broadness of the center of pressure from the force plate is related to Difficulty Describing Feelings, an important factor from a dispositional trait of Alexithymia. Implications of the use of such methods are discussed.