Software gearing in a virtual environment: the effect on perception of optic flow

W. A. Powell, B. Stevens, S. Hand, M. Simmonds

Research output: Contribution to journalArticlepeer-review


Immersing patients in a Virtual Reality environment whilst walking may engage and motivate them, stimulating a greater level of effort than exercise alone. Initial work has demonstrated that walking speed may be manipulated by controlling the rate of optic flow, which has potential for enhancing the recovery process for patients undergoing rehabilitation. However, it has been reported that there is a perceived mismatch between walking speed on a treadmill and the presented rate of optic flow when it is set to be equivalent to current walking speed. The consistency of this “gain mismatch”within and between participants is currently unclear and further clarification is needed if the beneficial effect of manipulating optic flow in a Virtual Rehabilitation setting is to be optimised. Preliminary findings of a study investigating this gain mismatch in a treadmill-mediated Virtual Environment indicate that substantial changes in optic flow are required before they are perceived as unmatched,and that slightly fast optic flow speeds are more likely to be perceived as normal than slightly slow optic flow speeds.
Original languageEnglish
Pages (from-to)100-107
JournalAnnual Review of CyberTherapy and Telemedicine
Publication statusPublished - 2007


  • optic flow
  • visual gain
  • treadmill
  • Virtual reality


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