Table 3. Principal component analysis results of each of the four stress tests (NA, NO, NH, WH) with eigenvalues, percentage of the total variance, and loadings of the rotated components (RC1 and RC2), along with communalities (= proportion of variance in the variable explained by the components).

Novel arena test (NA)	‘active in NA’ (RC1)	‘reactive in NA’ (RC2)	Communalities
Baseline-subtracted heart rate	0.0	0.7	0.5
Duration being inactive	−0.8	−0.1	0.6
Frequency of vocalisations	0.3	0.6	0.5
Frequency of segment changes	0.8	−0.1	0.7
Duration in inner segments	−0.3	0.7	0.6
Eigenvalue	1.5	1.3
% of variance	30.0	27.0
Novel object test (NO)	‘active in NO’ (RC1)	‘exploratory in NO’ (RC2)
Baseline-subtracted heart rate	−0.04	0.9	0.8
Duration being inactive	−0.8	−0.3	0.8
Frequency of object contacts	0.3	0.7	0.5
Frequency of segment changes	0.9	−0.01	0.8
Eigenvalue	1.6	1.3
% of variance	40.0	31.0
Novel human test (NH)	‘sociable in NH’ (RC1)	‘active in NH’ (−RC2*)
Baseline-subtracted heart rate	−0.6	−0.2	0.5
Duration being inactive	0.0	−0.9	0.8
Frequency of vocalisations	0.7	0.2	0.5
Frequency of human contacts	0.8	−0.2	0.7
Frequency of segment changes	0.2	0.9	0.8
Eigenvalue	1.7	−1.7
% of variance	34.0	−33.0
Weighing test (WH)	‘reactive in WH’ (PC)
Baseline-subtracted heart rate	0.6	–	0.4
Weighing score	−0.8	–	0.6
Exiting score	0.8	–	0.6
Eigenvalue	1.5	–	–
% of variance	51.0	–	–

Notes:

^*Loadings for this component were negated (multiplied by −1) for ease of interpretation.

Loadings above 0.5 and below −0.5 are shown in bold.