Palo Alto, California

SOROUSH Salehian raised both arms and spun in circles as if celebrating a touchdown.

Across the room, perched on a tripod, a small black device monitored this little dance and streamed it to a nearby laptop. Mr Salehian appeared as a collection of tiny coloured dots, some red, some blue, some green. Each dot showed the precise distance to a particular point on his body, while the colours showed the speed of his movements. As his right arm spun forward, it turned blue. His left arm, spinning away, turned red.