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Walking Variability and Working-Memory Load in Aging: A Dual-Process Account Relating Cognitive Control to Motor Control Performance

Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.

Address correspondence to Martin Lövdén, Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, D-14195 Berlin, Germany. E-mail: loevden{at}mpib-berlin.mpg.de.

Effects of cognitive activities on walking variability are poorly understood. We parametrically manipulated working-memory load by using an n-back task in 32 younger adults and 32 older adults walking on a treadmill at self-selected speed. We found no dual-task costs for cognitive performance. Stride-to-stride variability was lower when participants performed an easy working-memory task than when they walked without cognitive tasks. Increasing working-memory load from 1-back to 4-back produced decreasing variability of stride time and stride length in younger but not in older adults. Extending the 2006 dual-process account proposed by Huxhold, Li, Schmiedek, and Lindenberger, we conclude that normal aging alters the trade-off between the effects of focus of attention and resource competition on walking variability.

Key Words: Dual-task cost • Resource Competition • Walking variability