Motion and intensity shape accuracy and confusion patterns in emotion recognition

Facial expression recognition depends on both motion and intensity, but how these factors interact within and across emotions remains unclear. Here we examined recognition accuracy of basic emotions (anger, disgust, fear, joy, sadness, surprise) across low, medium, and high intensity displays of static and naturally dynamic facial expressions. Results showed while there was an overall increase in accuracy with intensity, there were complex interactions between intensity, motion, and emotion. Dynamic cues enhanced recognition of joy, surprise, and anger, particularly at low intensity, whereas disgust, fear, and sadness were recognised with greater accuracy from static expressions. We found common confusion patterns of fear-surprise, anger-sadness, and disgust-anger. However, contrary to reports of equivalent confusion patterns across dynamic and static expressions, motion reduced confusions of surprise as fear, but increased confusions of fear as surprise. This novel finding suggests that temporal unfolding facilitates recognition of surprise, but obscures cues aiding identification of fear. These patterns show that the benefits of dynamic information are intensity and emotion-specific and limited when emotions share morphological features. The current findings highlight the complexity of the role of motion and intensity in facial expression recognition and underscore the importance of employing naturally unfolding dynamic stimuli.