Background: Learning to use software using screencast videos with worked examples in the corresponding practice files presents a classic split-attention problem that requires learners to mentally integrate information from the video with a target application. While there is evidence that splitting attention either temporally or spatially adversely impacts learning, it is unclear if there is a meaningful difference in the load imposed by splitting attention in different ways. Furthermore, while much is known about effective screencast design, little is known about how learning environment features, such as the monitor configuration, influence learning from this form of instruction. Objective: An experiment was conducted with 42 novice learners to compare the effects of two common monitor configurations that divided attention differently on three physiological measures of cognitive load. Methods: Effects due to the monitor setup were assessed using a 2 × 2 study design that controlled for task order and working memory capacity. In one condition, subjects split attention temporally by toggling back and forth between the video and target application on one monitor. In contrast, the other condition required subjects to split attention spatially by shifting their gaze between the video and target application displayed on two side-by-side monitors. Results and Conclusions: Results indicated that cognitive load as measured through task-evoked pupil response was significantly higher, p < 0.05, for groups with two monitors during both instruction and testing, even after controlling for working memory capacity.