Table 1.
Summary of the dependent variables.
Figure 1.
For the assessment of alpha-amylase (AA) and cortisol (COR), saliva was sampled at discrete measurement timepoints between −10 min and 20 min/70 min relative to stressor onset. Visual Analogue Rating Scales (VARS) assessing stress-induced mood changes were administered at baseline (−10 min) and at the end of the anticipation phase/immediately before the onset of acute stress (0 min). The measurement period for the thermal infrared imaging (IRI) and Biopac assessments began at −10 min and ended at 15 min relative to stressor onset.
Figure 2.
Multivariate pattern analysis of phases in the stress cycle.
A Methods. For each subject (S1…15), responses patterns were created that included the n measures (M) of either established stress markers or thermal imprints of a particular test phase (anticipation, stress, recovery). Response patterns of all but one subject were used to train a classifier to identify physiological response profiles that are characteristic for each of the test phases. This was the basis for the subsequent prediction of the response patterns of the remaining subject as belonging to either anticipation, stress of recovery phase. B Results. Multivariate response patterns of established stress measures obtained for the CPT (MVPA 1, left) reliably predicted the current test phase of a subject well above chance (56% classification accuracy, p<.001). Patterns of thermal facial imprints in the CPT (MVPA 2, right), on the other hand, did not significantly predict the correct phase (40% classification accuracy, p = .13). The histograms display the permutation distribution of classification accuracies achieved by chance (average 33%).
Figure 3.
Means and ±SEM of all dependent variables (raw or logged scores) during baseline, anticipation, stress and recovery (sampling time points for alpha-amylase and cortisol) of CPT and TSST.
Table 2.
Univariate statistics (one-way repeated measures ANOVAS with simple contrasts) for raw (logged for alpha-amylase and cortisol) scores over time in CPT and TSST.
Table 3.
Tables 3. Pearson correlations between the change-sensitive candidates for each test phase in CPT and TSST.
Table 4.
Pearson correlations between the change-sensitive candidates and the anticipatory mood changes (anxiety and anger) per test phase in CPT and TSST.