Fig 1.
Experimental paradigms: No visual cues pathway (top left), visual cues pathway (top right) and device to occlude vision of the lower-limbs (bottom images).
Table 1.
Number of freezing of gait episodes and average percentage of trials spent frozen with respect to the four individuals with Parkinson’s disease who experienced freezing of gait episodes in experiment#1.
Table 2.
Demographic characteristics of participants with Parkinson’s disease who experience freezing of gait (freezers) and do not experience freezing of gait (non-freezers) in experiment#1.
Fig 2.
Significant gait interactions in Experiment #1 between dual-task and visual cues: Graphical illustration of a) step length, b) step time, c) double support time percentage, and d) velocity collapsed across groups when participants performed either the “dual-task” (gray) or “no dual-task” (black) conditions while walking on either the “no visual cues” pathway or “visual cues” pathway.
* represents a significant difference at the p<0.05 level.
Table 3.
Experiment #1 spatiotemporal gait parameter effects and interactions.
Fig 3.
Significant gait interactions in Experiment #1 between group and visual Cues: Graphical illustration of a) step length, b) step time, c) double support time percentage, and d) velocity of the freezers and non-freezers as a result of walking toward and through a narrowed doorway on either the “no visual cues” pathway (black) or the “visual cues” pathway (gray).
Each parameter includes both “no dual-task” and “dual-task” conditions collapsed. * represents a significant difference at the p<0.05 level.
Fig 4.
Significant gait variability interactions in Experiment #1: Graphical illustration of a) group x dual-task interaction for step length variability, b) dual-Task x visual cues interaction for step time variability, and c) group x dual-task x visual cues interaction for double support time percentage variability.
* represents a significant difference at the p<0.05 level.
Fig 5.
Significant gaze interactions in Experiment #1 between group, dual-task, visual cues, phase, and area of interest: Graphical illustration of the percentage of total fixation duration towards the pathway (top graphs), doorway (middle graphs) and through the doorway (bottom graphs) of the freezers (blue) and non-freezers (red) in the early, middle and late phases of walking toward and through the narrowed doorway in the “dual-task” or “no dual-task” conditions on either the “no visual cues” pathway or the “visual cues” pathway.
* represents a significant difference at the p<0.05 level uncovered with Fisher’s LSD analysis. Blue parenthetical lines represent differences within the freezer group, and red parenthetical lines represent differences within the non-freezer group.
Table 4.
Number of freezing of gait episodes and average percentage of trials spent frozen with respect to the four individuals with Parkinson’s disease who experienced freezing of gait episodes in both experiments collapsed.
Table 5.
Demographic characteristics of participants with Parkinson’s disease that experience freezing of gait (freezers) and do not experience freezing of gait (non-freezers) for individuals who participated in the second experiment.
Fig 6.
Significant gait interactions in Experiment #2 between group and condition.
Graphical illustration of a) step length, b) step time, c) double support time percentage, and d) velocity of the freezers (black) and non-freezers (gray) as a result of walking toward and through a narrowed doorway in either the i) lower-limb occlusion (LLO), ii) lower-limb occlusion and visual cues (LLO+VC), or iii) lower-limb occlusion, visual cues and dual-task (LLO+VC+DT) conditions. * represents a significant difference at the p<0.05 level.
Table 6.
Experiment #2 spatiotemporal gait parameter effects and interactions.
Fig 7.
Significant gaze interactions in Experiment #2 between group and condition.
Graphical illustration of the percentage of total fixation duration towards the pathway (left graph), doorway (middle graph) and through the doorway (right graph) of the freezers (blue) and non-freezers (red) in the i) Lower-limb occlusion (LLO), ii) Lower-limb occlusion and visual cues (LLO+VC), and iii) Lower-limb occlusion, visual cues and dual-task (LLO+VC+DT) conditions. * represents a significant difference at the p<0.05 level uncovered with Fisher’s LSD analysis. Blue parenthetical lines represent differences within the freezer group, and red parenthetical lines represent differences within the non-freezer group.