Table 1.

Result of principal component analysis on six pupil characteristics (AUC, maximum, minimum, latency to maximum, maximum positive derivative, maximum negative derivative). Left table shows variable loadings on each of the resulting principal components. Right table shows the percent of variance explained by each principal component. This analysis used dynamic range normalized data

	Principal component loadings
Variables	1	2	3	4	5	Component	% explained
AUC	0.16	0.99	< 0.001	< 0.001	< 0.001	1st	90.82
Maximum	< 0.001	< 0.001	− 0.49	0.87	− 0.045	2nd	9.81
Minimum	< 0.001	< 0.001	0.87	0.49	0.027	3rd	< 0.001
Latency to max	0.99	− 0.15	< 0.001	< 0.001	< 0.001	4th	< 0.001
Max. pos. Deriv	< 0.001	< 0.001	− 0.035	0.018	0.84	5th	< 0.001
Max. neg. Deriv	< 0.001	< 0.001	0.024	− 0.024	− 0.54	6th	< 0.001