Fig 1.
Top panel: Framework indicating demands examined with multitask locomotor research. Relatively lower demands are on the left, with increasing demands to the right in red. Demands of the current study are demonstrated with blue vertical arrows (note that the arrow position demonstrates relative differences across conditions and studies, and it not intended to reflect absolute differences or locations on the spectrum). Two examples of previous sensory interference research are also indicated: (1) * foot target task [13] and (2) + obstacle task [19]. Bottom panel: Information about each study. All studies compared low versus high visual sensory interference. The current study focuses on the less difficult side of the framework, to determine if visual sensory interference alters performance under low levels of cognitive, temporal, and gait demand.
Fig 2.
(A) Line drawing of the walkway, obstacle, and RT cue. In the walking conditions, the RT cue was triggered 0–1.5 s (corresponds to gray region) after the participant broke the laser beam (positioned at hip height). The RT cue appeared once during approach, either on the obstacle (low sensory interference (SI)) or at eye-level (high SI). Participants pressed a hand-held remote when the RT light cue turned on. HD-1 and HD+1 represent the horizontal distance from the obstacle to the trail toe and the lead heel, respectively. (B) The block-randomized protocol. In the standing conditions, participants stood 1.5 m in front of the obstacle, and the RT cue appeared on either the obstacle or at eye-level. For standing trials, there was no SI regardless of light cue location. SI = sensory interference.
Table 1.
The percent value in the last column is percent of all trials.
Fig 3.
(A) Mean reaction time as a function of task and sensory interference. An interaction of sensory interference by task was observed (p<0.001); post hoc differences noted with *. (B) Mean reaction time as a function of age, task, and block. An interaction of age by task by block was observed (p = 0.004); post hoc differences noted with §. Error bars represent standard error. SI = sensory interference.
Fig 4.
(A) Mean trail foot placement before the obstacle (HD-1) as a function of sensory interference in younger and older adults. An interaction of sensory interference by age was observed; post hoc differences noted with #. (B) Mean lead foot placement after the obstacle (HD+1) for young and older adults. An age main effect was observed (p = 0.01) and noted with †. Error bars represent standard error. SI = sensory interference.
Fig 5.
Mean gait speed as a function of step, sensory interference, and age group.
The footprint figures indicate the step where speed was calculated for each of the three steps (one-step before the obstacle crossing, the lead step across the obstacle, and the trail step after the obstacle). For each of the three steps, two main effects were observed: (1) age (p<0.001); post hoc differences noted with +, and (2) sensory interference (p<0.001); post hoc differences noted with *. Error bars represent standard error. SI = sensory interference.