2.3. Experimental Design
A 2 × (2 × 14) mixed design was implemented to represent the experimental design with one between-subject variable and one within-subject variable. The first independent variable, which was treated as a between-subject variable, is the instruction methods at two levels (i.e., AR-based instructions and paper-based instructions). The second independent variable, which was treated as a within-subject variable, is the task complexity with two levels (i.e., low-demanding task and high-demanding task). The dependent variables were the EEG power spectrum density of alpha, beta, and theta in the frontal, temporal, parietal, and occipital brain regions and the perceived workload (NASA-TLX).