People working in an office environment often have to deal with significant cognitive workload due to the coordination of multiple, simultaneous tasks. The objective of this research was to examine the impact of cognitive load in officetype tasks on physical-stress response, using a dual-task paradigm involving a primary cognitive task and secondary typing task. The central hypothesis of this research was that altering the demands of the cognitive task would lead to a difference in physical stress-level and performance. Cognitive load was manipulated by presenting participants with three different types of cognitive tasks described in Rasmussen's (1983) taxonomy, including skill-, rule-, and knowledge-based tasks. Dependent variables examined in the study included: (1) electromyographic activity of the upper trapezius (pars descendens) and cervical erector spinae muscles, (2) performance in a secondary typing task, and (3) subjective measures of stress and cognitive workload. The results of this study revealed that the primary task causing the highest level of perceived workload also produced 61% higher muscle activity in the right trapezius, and 6 and 11% higher activity in the left and right cervical erector spinae, respectively, in comparison to muscle activity associated with the cognitive task causing the lowest perceived workload. With respect to performance, a 23% decrease was observed in typing productivity when the rule-based task was completed simultaneously vs. typing in the absence of any additional cognitive task (the baseline condition). This information may be used to better organize work activities in office environments to increase performance and reduce stress.

Workers in office environments often have to deal with high cognitive workload due to the coordination of multiple work tasks. The objective of this research was to use a dual-task paradigm to examine the impact of cognitive load in office-type tasks on the cervicobrachial muscle activity response and performance. Cognitive load was manipulated by presenting subjects with examples of the three different types of cognitive tasks described in Rasmussen's (1983) taxonomy, including skill-, rule-, and knowledge-based tasks while they performed a secondary typing task. Performance in the secondary task, cervicobrachial muscle activity, and subjective measures of perceived stress and mental workload were the dependent measures. Results showed a significant effect of the different cognitive tasks. The cognitive task causing the highest level of subjective workload also produced 66.67% higher muscle activity in the right trapezius, and 8.33% and 10.53% higher activity in the left and right cervical erector spinae, respectively, in comparison to muscle activity associated with the cognitive task causing the lowest perceived workload. With respect to performance, a 29.8% decrease was observed in typing productivity when the rule-based task was completed as compared to typing with no additional cognitive load.