Different indicators are interesting for analyzing human learning processes. Recent studies analyze learning performance in combination with cognitive load, as an indicator for learners’ invested mental effort. In order to compare different measures of cognitive load research, the present study uses three different objective methods and one subjective method, reviewing the seductive details effect in a computer-based multimedia learning instruction. An experimental two-group design (N = 50) was used, with exposure to seductive details during learning as the between group factor. Eye movements were analyzed concerning the indicated cognitive activity and cognitive load was measured by the rhythm method (Park 2010; Park and Brünken 2015), the index of cognitive activity (ICA) (Marshall 2007), as well as by subjective ratings of mental effort and task difficulty (Paas 1992). Results confirm the seductive details effect for learning success with a decrease in retention and comprehension performance, an increase in total cognitive activity indicated by eye movements and significant higher cognitive load, indicated by rhythm method. The ICA values and the subjective ratings on mental effort and task difficulty show no difference in cognitive load between the groups. The results provide evidence of the suitability of different objective measures for a direct and continuous cognitive load assessment in multimedia learning. Further, the results show the benefit of combining different methods to gain detailed insight into information processing while learning with multimedia as well as a differentiated access to the single cognitive load factors.