Abstract
Previous inquiry suggests that the constriction of the muscle around the eye serves to intensify smiling expressions. This study investigated whether eye constriction not only leads smiling expressions to be more positive but also leads negative (cry-face) expressions to be more negative. Twelve parents and their 6-month old infants interacted within a protocol designed to elicit positive and negative emotion (the Face-to-Face Still-Face). Facial actions were measured frame-by-frame from video using automated methods (computer vision and pattern recognition). Non-experts rated positive and negative affect. Eye constriction intensity (obicularis oculi pars orbitalis) was associated with both smiling (zygomatic major) and lateral lip-stretching (action of the risorius, a component of the cry-face expression) intensity. Eye constriction intensity predicted both positive and negative emotion ratings, beyond the effects of smiling and lateral lip-stretching intensity, respectively. These finding suggest that eye constriction serves an intensifying role in both positive and negative infant expression.