Using the principals of facial caricature to exaggerate human motion

The ways in which we move our faces and bodies are the source of much biologically important information. Such movements can be exaggerated by extending techniques developed for static facial caricature into the temporal domain. Spatial exaggeration of movement is accomplished by first time-normalising the sequences to be exaggerated and then exaggerating the differences between individual frames and an average frame. We can also exaggerate the temporal properties of movement by reversing and extrapolating the time-normalisation step. Previous findings from a variety of domains where exaggeration has been shown to enhance the perception of task-relevant information are reviewed, together with new data showing that spatial exaggeration of emotional utterances relative to an averaged utterance can enhance their perceived happiness, sadness, or angriness. Conversely, it is argued that exaggerating emotional or other individual differences may actually interfere with the recovery of information common to all the sequences being averaged, in this case the lexical content. Lastly, motion exaggeration, like facial caricature, may reflect general underlying principles involved in the encoding and discrimination of biological movement, an as yet poorly understood process