If there’s one familiar sound whenever a volunteer tries out an interactive device that uses electrical muscle stimulation (EMS), it is probably laughter. Even for experienced users of the technology, the sensation of a machine controlling your body, rather than the other way around, feels unnatural and strange. Something about the experience disrupts people’s sense of agency — the feeling of being in control of one’s actions — which could interfere with the potential of EMS to improve learning, make virtual reality more realistic, and many other applications.
As Pedro Lopes explored EMS devices through a human-computer interface lens, first in his doctoral work at the Hasso Plattner Institute in Germany and ongoing today at UChicago CS, he grew interested in whether agency can be measured, controlled, or even restored during EMS use. In two recent papers at the international SIGCHI conference in Glasgow and a new publication in the neuroscience journal Cerebral Cortex, Lopes and collaborators have been on the trail of agency, using everything from pitching machines to fMRI brain scanners.
“We started by asking the question, does EMS always have to feel that unnatural, or is there anything we can do to make it feel more in tune with your own volition?,” Lopes said. “I think we just started to answer it, but there are infinite ways to look at this thing because it's such a philosophical question.”
The agency pursuit started with a simple demo performed at the SIGGRAPH 2018 conference by Jun Nishida, who's now a postdoctoral researcher at UChicago CS: can EMS help people catch a marker dropped by another person at short range? It did, and as expected, most volunteers attributed the action to the machine, not their own reflexes. But a small minority of participants disagreed, saying that the EMS must not have been on because they caught the marker unassisted. What happened?