Recognizing face identity from natural and morphed smiles.

It is easier to identify a degraded familiar face when it is shown moving (smiling, talking; nonrigid motion), than when it is displayed as a static image (Knight & Johnston, 1997; Lander, Christie, & Bruce, 1999). Here we explore the theoretical underpinnings of the moving face recognition advantage. In Experiment 1 we show that the identification of personally familiar faces when shown naturally smiling is significantly better than when the person is shown artificially smiling (morphed motion), as a single static neutral image or as a single static smiling image. In Experiment 2 we demonstrate that speeding up the motion significantly impairs the recognition of identity from natural smiles, but has little effect on morphed smiles. We conclude that the recognition advantage for face motion does not reflect a general benefit for motion, but suggests that, for familiar faces, information about their characteristic motion is stored in memory.