Human sensitivity to dynamic translational gains in head-mounted displays

Translational gains in head-mounted display (HMD) systems allow a user to walk at one rate in the real world while seeing themselves move at a faster or slower rate. Although several studies have measured how large gains must be for people to recognize them, little is known about how quickly the gains can be changed without people noticing. We conducted an experiment where participants were asked to walk on a straight path while wearing an HMD while we dynamically increased or decreased their virtual world translation speed. Participants indicated if their speed increased or decreased during their walk. In general, we found that the starting gain affected the detection and that, in most cases, there was little difference between gradual and instantaneous gain changes. The results of this work can help inform redirected walking implementations and other HMD applications where translational gains are not constant.