Cardiovascular measures have been found to be sensitive to task onset and offset, but are less sensitive to adjacent levels of increasing cognitive workload. A potential confound in the literature is the disregard of individual differences in cardiovascular reactivity. In particular, the individuals' working memory capacity (WMC) is likely to play a role in cardiovascular reactivity to workload. A total of 98 university students performed four cognitive tasks that varied in their level of workload. The operation span (OSPAN) task was used to measure the participants' WMC. A variety of cardiovascular measures were gathered in real time during the experiment. Derived measures of blood pressure regulation were also calculated. In line with what was hypothesized, cardiovascular measures detected workload onset and offset but did not consistently distinguish between the individual task levels. Furthermore, a significant interaction between workload levels and WMC showed that cardiovascular profile varied depending on WMC scores. In addition, WMC negatively predicted subjective ratings of task difficulty as well as task performance, with subjective estimation of task difficulty and error increasing as WMC decreased. The results suggest that WMC may play a critical role in determining how individuals react to increased cognitive workload.
Keywords: Blood pressure; Blood pressure regulation; Cardiovascular reactivity; Cognitive workload; Heart period; Heart rate; Individual difference; Working memory capacity; Workload monitoring.
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