Aging and Movement Laboratory, Bruyère Research Institute, 43 Bruyère Street, Ottawa, ON, K1N 5C8, Canada,
Exp Brain Res. 2013 Nov;231(2):219-29. doi: 10.1007/s00221-013-3684-0. Epub 2013 Aug 31.
The dual-task paradigm has previously been used to investigate the attentional demands associated with postural control. Previous studies have identified both the focus of attention and the difficulty of a postural task as potential factors influencing dual-task performance. The aim of this study was to examine how the instructed focus of attention influences dual-task performance during quiet standing tasks of various levels of difficulty. Thirteen young adults participated in two testing sessions consisting of standing as still as possible on a force platform in different postural conditions, while simultaneously performing a simple reaction time (RT) task. Postural task difficulty was manipulated by various combinations of three bases of support (feet together, tandem and single leg) and two visual conditions (eyes opened and closed). Participants were instructed to focus on either their balance or their RT performance, depending on the testing session. When comparing postural control with respect to session focus, anterior-posterior sway velocity decreased with the addition of the simple RT task when the focus was on balance, but only during the more difficult dual-task conditions. In contrast, sway area and medial-lateral sway velocity did not change between the two instructed focus sessions. Participants responded faster in all dual-task conditions when focusing on RT performance than on balance. The modified attention allocation index indicated that participants' ability to modulate their allocation of attentional resources to respond positively to instruction was more pronounced in the most challenging postural condition. The present findings could have important implications for the interpretation of dual-task performance in both clinical and research settings.
双重任务范式以前曾被用于研究与姿势控制相关的注意力需求。以前的研究已经确定了注意力的焦点和姿势任务的难度是影响双重任务表现的潜在因素。本研究旨在探讨在不同难度的静立任务中，指令注意力焦点如何影响双重任务表现。13 名年轻人参加了两个测试会议，包括在不同的姿势条件下尽可能站在力台上，同时执行简单的反应时间（RT）任务。通过三种支撑基础（双脚并拢、前后脚并拢和单脚）和两种视觉条件（睁眼和闭眼）的不同组合来操纵姿势任务的难度。参与者根据测试会议被指令专注于平衡或 RT 表现。当比较与会议焦点有关的姿势控制时，当焦点放在平衡上时，添加简单的 RT 任务会降低前后摇摆速度，但仅在更困难的双重任务条件下。相比之下，在两个指令焦点会议之间，摇摆区域和左右摇摆速度没有变化。当专注于 RT 表现时，参与者在所有双重任务条件下的反应速度都更快。改良的注意力分配指数表明，参与者在最具挑战性的姿势条件下更能调节注意力资源的分配，以积极响应指令。本研究结果对于在临床和研究环境中解释双重任务表现可能具有重要意义。
