Two studies investigated the importance of dynamic temporal characteristic information in facilitating the recognition of subtle expressions of emotion. In Experiment 1 there were three conditions, dynamic moving sequences that showed the expression emerging from neutral to a subtle emotion, a dynamic presentation containing nine static stills from the dynamic moving sequences (ran together to encapsulate a moving sequence) and a First-Last condition containing only the first (neutral) and last (subtle emotion) stills. The results showed recognition was significantly better for the dynamic moving sequences than both the Dynamic-9 and First-Last conditions. Experiments 2a and 2b then changed the dynamics of the moving sequences by speeding up, slowing down or disrupting the rhythm of the motion sequences. These manipulations significantly reduced recognition, and it was concluded that in addition to the perception of change, recognition is facilitated by the characteristic muscular movements associated with the portrayal of each emotion.
Bould, E., Morris, N., & Wink, B. (2008). Recognising subtle emotional expressions: The role of facial movements. Cognition and Emotion, 22(8), 1569–1587. https://doi.org/10.1080/02699930801921156