Fig. 4.

Co-variation of phasic changes in arousal across measures. All data available across the entire 20-min testing session was epoched into 20-s segments (approximately 60 epochs per individual). For each possible pairwise combination of variables, the rank order correlation between those measures was calculated across all epochs available for that participant. Individual dots on the scatterplots show, participant by participant, the rank order correlation observed between that pair of variables. Consistently positive (>0) correlations suggest a positive relationship between variables. In order to assess whether the correlations observed across all individuals differ significantly from zero, a one-sample t-test was calculated. The mean correlations observed (μ) and the significance levels (p) of these tests are shown in red. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)