ABSTRACT
Motor performance is influenced by the interplay among an individual’s physical characteristics, task demands, and the environment. When there is a mismatch among these variables, performance can be compromised, even during routine tasks such as walking. In the worst case, falls and injury may occur. Age is one of the most common individual characteristics that affect movement, viz., older persons show greater variability in gait and tend to fall more frequently than younger adults during typical activities of daily living (Kressig, 2004). Task demands play a critical role in how a person executes the motor requirements of a given activity. For example, when an individual engages in a physical and mental task simultaneously, performance of one or both activities may deteriorate (Beauchat et al., 2003; Melzer & Oddsson, 2004; Pellecchia, 2003; Woollacott & Shumway-Cook, 2002). The pace at which a person executes a task may also affect the quality of movement and outcome. Fast walking speed has been implicated in healthy older adults’ failing to recover balance and falling following a trip or stumble (Pavol, Owings, Foley, & Grabinder, 2001). Suboptimal environmental conditions, such as those that limit visual input, have been associated with diminished postural stability and increased risk of falls (Kinsella-Shaw, Harrison, Colon-Semenza, & Turvey, 2006). Lighting variations and walking quickly are common occurrences that may present risks to upright balance during static or dynamic tasks. Performing multiple tasks in less than optimal conditions (e.g., dim lighting or quickened pace) may have safety implications, especially as people age or experience compromised mobility. The purpose of this study was to investigate how commonplace, non-optimal conditions affect a person’s ability to carry out concurrent cognitive and physical tasks (dual tasking). More specifically, the study examined the relationships among age, performance of simultaneous cognitive and physical tasks, demand of moving quickly while walking, and the level of illumination.
