Perception of dynamic point light facial expression

This study uses point light displays both to investigate the roles of global and local motion analyses in the perception of dynamic facial expressions and to measure the information threshold for reliable recognition of emotions. We videotaped the faces of actors wearing black makeup with white dots while they dynamically produced each of 6 basic Darwin/Ekman emotional expressions. The number of point lights was varied to systematically manipulate amount of information available. For all but one of the expressions, discriminability (d′) increased approximately linearly with number of point lights, with most remaining largely discriminable with as few as only 6 point lights. This finding supports reliance on global motion patterns produced by facial muscles. However, discriminability for the happy expression was notably higher and largely unaffected by number of point lights and thus appears to rely on characteristic local motion, probably the unique upward curvature of the mouth. The findings indicate that recognition of facial expression is not a unitary process and that different expressions may be conveyed by different perceptual information, but in general, basic facial emotional expressions typically remain largely discriminable with as few as 6 dynamic point lights