Squeeze The Pain Away: Using a Wireless Ball to Measure Efforts to Reduce Other’s Pain Expressions in VR

Virtual reality has often been used as a tool to study empathy. However, few studies have explored users’ willingness to make physical effort to actively reduce others’ pain. We developed a pipeline that integrates a wireless stress ball into a VR environment. This device measures continuous grip force, enabling participants to adjust a virtual character’s pain expressions through squeezing: the harder they squeeze, the less intense the pain expressions become in real-time. This shifts the participants’ focus from passive observation to active participation. Our results indicated that participants were highly motivated to use the ball to reduce virtual characters’ pain and showed particularly high use of effort in the first 10 seconds of a 15-second trial. Eye-tracking data revealed that participants focused primarily on pain-related facial features, consistent with previous pain decoding studies. Our effort-based approach offers a novel method to study pain perception.