Journal article
How humans use visual optic flow to regulate stepping during walking
Gait & posture, Vol.57, pp.15-20
09/2017
DOI: 10.1016/j.gaitpost.2017.05.002
PMID: 28570860
Abstract
•Humans use optic flow (OF) to regulate locomotion speed.•Systematically manipulated OF to determine influence on stepping strategies.•OF speed manipulations influenced stride speed and treadmill position variability.•At slower OF rates, adults corrected stride speeds more actively with less variability.•Results consistent with Weber’s law: uncertainty increased with stimulus magnitude.
Humans use visual optic flow to regulate average walking speed. Among many possible strategies available, healthy humans walking on motorized treadmills allow fluctuations in stride length (Ln) and stride time (Tn) to persist across multiple consecutive strides, but rapidly correct deviations in stride speed (Sn=Ln/Tn) at each successive stride, n. Several experiments verified this stepping strategy when participants walked with no optic flow. This study determined how removing or systematically altering optic flow influenced peoples’ stride-to-stride stepping control strategies. Participants walked on a treadmill with a virtual reality (VR) scene projected onto a 3m tall, 180° semi-cylindrical screen in front of the treadmill. Five conditions were tested: blank screen (“BLANK”), static scene (“STATIC”), or moving scene with optic flow speed slower than (“SLOW”), matched to (“MATCH”), or faster than (“FAST”) walking speed. Participants took shorter and faster strides and demonstrated increased stepping variability during the BLANK condition compared to the other conditions. Thus, when visual information was removed, individuals appeared to walk more cautiously. Optic flow influenced both how quickly humans corrected stride speed deviations and how successful they were at enacting this strategy to try to maintain approximately constant speed at each stride. These results were consistent with Weber’s law: healthy adults more-rapidly corrected stride speed deviations in a no optic flow condition (the lower intensity stimuli) compared to contexts with non-zero optic flow. These results demonstrate how the temporal characteristics of optic flow influence ability to correct speed fluctuations during walking.
Details
- Title: Subtitle
- How humans use visual optic flow to regulate stepping during walking
- Creators
- Mandy M Salinas - Department of Kinesiology & Health Education, University of Texas, Austin, TX 78712, USAJason M Wilken - Center for the Intrepid, Brooke Army Medical Center, JBSA Ft. Sam Houston, TX, USAJonathan B Dingwell - Department of Kinesiology & Health Education, University of Texas, Austin, TX 78712, USA
- Resource Type
- Journal article
- Publication Details
- Gait & posture, Vol.57, pp.15-20
- Publisher
- Elsevier B.V
- DOI
- 10.1016/j.gaitpost.2017.05.002
- PMID
- 28570860
- ISSN
- 0966-6362
- eISSN
- 1879-2219
- Grant note
- name: BADER Consortium; DOI: 10.13039/100000005, name: Department of Defense; name: Congressionally Directed Medical Research Program cooperative agreement, award: W81XWH-11-2-0222
- Language
- English
- Date published
- 09/2017
- Academic Unit
- Physical Therapy and Rehabilitation Science
- Record Identifier
- 9984047898302771
Metrics
23 Record Views