Table 2.

Signal-to-signal analysis techniques and the general question each can address

Method	Question
Correlation	To what degree do the signals change together?
Cross-Correlation	To what degree do the signals change together, when allowing for different temporal lags between them?
Inter/Intra subject correlation	To what degree do the pupil traces across participants, or within a single participants’ repeated exposure to the same stimulus, change together?
Reverse correlation	Which events lead to moments of change in pupillary activity?
Regression	How well can we predict one signal given another?
Dynamic time warping	How (dis)similar are the signals with respect to changes in amplitude, when allowing for warping in time?
Inter-site phase clustering	How well are the signals aligned in phase, at specific frequencies, irrespective of power?
Magnitude squared coherence	How well are the signals aligned in phase, at specific frequencies, when accounting for power?
Detrended cross-correlation	Do the signals exhibit similar scale-free dynamics?
Cross-recurrence quantification	Do subsections of the signals repeat in a coupled way?