Table 1.

All features calculated from measured physiological signals (PPG, EDA and SKT).

Measure	Description	Section
	PPG
${\mathrm{HR}}_{\mathrm{avg}}$	Average heart rate	Time-domain measures
${\mathrm{NN}}_{\mathrm{avg}}$	Average NN intervals
SDNN	Standard deviation of NN intervals
SDSD	Standard deviation of difference between adjacent NN intervals
RMSSD	Square root of the mean of the sum of the squares of the difference between adjacent NN intervals
pNN20	(Number of pairs of adjacent NN intervals differing by more than 20 ms)/(total number of NN intervals)
pNN50	(Number of pairs of adjacent NN intervals differing by more than 50 ms)/(total number of NN intervals)
${\mathrm{LF}}_{\mathrm{normal}}$	Average of normalized low-frequency component (0.04–0.15 Hz) power	Frequency-domain measures
${\mathrm{HF}}_{\mathrm{normal}}$	Average of normalized high-frequency component (0.15–0.4 Hz) power
LF/HF	Ratio between averages of low-frequency and high-frequency powers
ApEn (2, 0.2)	Approximate entropy of NN intervals (m = 2 r = 0.2 × SDNN)	Nonlinear measures
SampEn (2, 0.2)	Sample entropy of NN intervals (m = 2 r = 0.2 × SDNN)
SD1	Standard deviation of data perpendicular to the axis of line-of-identity in Poincaré plot
SD2	Standard deviation of data along the axis of line-of-identity in Poincaré plot
SD1/SD2	Ratio between SD1 and SD2
	EDA
${\mathrm{SC}}_{\mathrm{avg}}$	Average of total skin conductance (SC) signal	SC measure
${\mathrm{SCL}}_{\mathrm{avg}}$	Average of total SC level (SCL) signal	SCL measures
${\mathrm{SCL}}_{\mathrm{slope}}$	Difference between maximum SCL and minimum SCL
${\mathrm{SCR}}_{\mathrm{avg}}$	Average of total SC response (SCR) signal	SCR measures
${\mathrm{SCR}}_{\max }$	Maximum SCR signal
${\mathrm{SCR}}_{\mathrm{peak}}$	Number of peaks in the SCR signal
	SKT
${\mathrm{SKT}}_{\mathrm{avg}}$	Average of total SKT signal	SKT measures
${\mathrm{SKT}}_{\mathrm{slope}}$	Difference between maximum SKT and minimum SKT
${\mathrm{SKT}}_{\mathrm{std}}$	Standard deviation of total SKT signal