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Joanna Lewis, Audrey Hill, Corey Bohil, Mark Neider; Divided Attention While Walking: Examining Functional Changes in Prefrontal Activity in Translational Contexts. Journal of Vision 2013;13(9):648. doi: 10.1167/13.9.648.
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Recent research has demonstrated our limited ability to divide attention between two tasks, such as when walking while talking on a cell phone (Neider et al., 2010). However characterizing performance costs in these types of dual-task scenarios, particularly those in the translational context, has previously been limited to measurement of task errors and completion times. Our study addressed this by using a portable functional near-infrared spectroscopy (fNIRS) system to characterize changes in functional activity in dorsolateral prefrontal cortex (PFC) while participants walked and performed backward counting tasks of varying attentional load. Previous research found that PFC recruitment increased when cognitive load increased from a single-task (walking) to a dual-task (walking while talking) (Hotzler et al., 2011). Accordingly, we expected additional increases in secondary task difficulty to correlate with increased PFC activity. All participants completed a series of 25 ft walks, both with and without a secondary task. Attentional load was manipulated between-subjects (7 low load; 7 high load) by varying backwards counting increments (either by 1’s/low load or 7’s/high load). Participants in the low load condition made significantly fewer counting errors and completed more counting iterations than those in the high load condition. PFC activity increased generally for the high load condition compared to walking only, but low load did not significantly change as compared to the control condition. Importantly, no differences in PFC activation were found between groups in the walking-only trials. These data support the hypothesis that the increased effort associated with divided attention while walking is reflected in increased PFC recruitment; the more demanding the attentional load the greater the demand on neural resources. We speculate that limitations in these resources might be the determining factor in dual-task related performance failures.
Meeting abstract presented at VSS 2013
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