The objective of this study was to quantify cognitive effort IWA and control participants dedicate to verbal compared with spatial working memory tasks using HRV. Researchers have found that non-brain injured adults’ physiological stress response is not affected by task type (Callister, Suwarno, & Seals, 1992), but by task difficulty (Fairclough & Houston, 2004; Gendolla & Richter, 2006; Iani, et al., 2004; Ryu & Myung, 2005). Assuming IWA have an impaired ability to allocate effort to the tasks, it was predicted that they would demonstrate no change in HRV from baseline to task for either verbal or spatial tasks. Further, a significant positive relationship between change in HRV and task performance was predicted for control participants, but none was expected for IWA
