Table 1. Internal consistency of cognitive load measures in response to task difficulty.

The table presents Cronbach’s α overall and within each task. The reliability coefficient could not be calculated for the BCPD measure in the Control tasks as it was treated as the baseline. Note the meaning of abbreviations in the table: MM (Microsaccades Magnitude), MR (Microsaccade Rate), PV-M (Microsaccade Peak Velocity—Magnitude), CPD (Intra-Trial Change in Pupil Dilation), BCPD (Inter-Trial Change in Pupil Dilation).

Variable	Overall	Task
		Control	Easy	Difficult
MM (deg)	0.96	0.97	0.95	0.97
MR (Hz)	0.96	0.96	0.96	0.96
MPV-M intercept	0.82	0.85	0.79	0.83
MPV-M slope	0.80	0.88	0.78	0.57
CPD	0.86	0.84	0.94	0.73
BCPD	0.95	—	0.92	0.95
NASA-TLX	0.88	0.83	0.87	0.77