Changes in motor actions in the face of varying task constraints

Walking is an everyday activity that requires modifying patterns based on constraints posed by the environment. Meeting multiple constraints at once increases the challenge of modifying motor actions.

We asked if adults' strategies in adapting to spatial and temporal constraints were similar and if they would prioritize one constraint over the other when completing both.

Across three tasks, we investigated how adults altered their walking to cope with crossing obstacles (Task 1; N = 30), walking to a metronome beat (Task 2; N = 32), and crossing obstacles while walking to a metronome beat (Task 3; N = 30).

Adults recalibrated to their baseline gait, but showed carryover effects after meeting a temporal constraint (allps>.05). We found an effect on the magnitude of deviation from metronome paces (F(262) = 58.86, p<.01). At the slow pace, participants stepped sooner than the beat, and at the fast pace they stepped later than the beat (all ps<.01). Adults altered the kinematics of their walking in response to a spatial constraint, but changed both the kinematics and kinetics of their walking patterns to meet temporal and combined spatial and temporal constraints. When attempting to meet both a spatial and temporal constraint simultaneously, they stepped sooner than the beat at all metronome paces (all ps<.01).

Our findings show separate walking strategies in adapting to spatial and temporal constraints. The presence of more than one constraint leads to prioritizing one over the other (i.e., a spatial constraint over a temporal constraint). These findings highlight that strategies for meeting constraints are dependent upon the type and number of constraints presented.