Assessing the association of university stress and physiological reactivity with decision-making among students

Figures & data

Table 1. Mean scores for sAA and heart rate variability indices across conditions (N = 79).

			Comparison
Variable	(1)Pretest	(2)RT	1 vs. 2
	M (SD)	M (SD)	d	p
sAA (U/mL)	158.27 (109.61)	134.38 (92.15)	0.23	.003
SDNN (ms)	48 (19)	53 (24)	0.21	.014
RMSSD (ms)	39 (20)	40 (22)	0.07	.502

U/mL: units per milliliter; ms: millisecond; sAA: salivary alpha-amylase; SDNN: standard deviation of the normal RR intervals; RMSSD: HRV measure of parasympathetic activity.

Table 2. Pearson correlation coefficients for the study variables.

	Age	ERI	OC	sAA (pre)	sAA (RT)	SDNN (pre)	SDNN (RT)	RMSSD (pre)
ERI	0.248*	–
OC	0.289**	0.568**	–
sAA (pre)	−0.238*	0.122	−0.191	–
sAA (RT)	−0.186	0.059	−0.177	0.773**	–
SDNN (pre)	−0.008	−0.030	−0.104	0.066	−0.068	–
SDNN (RT)	−0.021	−0.008	−0.059	0.064	0.074	0.837**	–
RMSSD (pre)	−0.023	−0.052	−0.050	0.067	−0.076	0.955**	0.816**	–
RMSSD (RT)	0.013	−0.040	−0.050	0.066	0.190	0.621**	0.921**	0.632**

*p < .05, **p < .01. RT: RT phase; Pre: pretest phase; ERI: effort-reward imbalance; OC: overcommitment; sAA: salivary alpha amylase; SDNN: standard deviation of the normal RR intervals; RMSSD: HRV measure of parasympathetic activity.

Table 3. Hierarchical regression Analyses assessing the relationship between psychological and physiological variables (pretest and RT phases) with simple and choice reaction time, after controlling for age.

	Simple RT					Choice RT
	Final summary			Step summary		Final summary			Step summary
Predictor	Beta	r	sr	R^2Δ	p	Beta	r	sr	R^2Δ	p
Step 1				0.026	.157				0.018	.243
Age	0.09	0.16	0.08			0.01	0.13	0.01
Step 2				0.046	.163				0.162	.001
ERI	0.22	0.20	0.17			−0.04	0.25*	−0.03
OC	−0.05	0.05	−0.04			0.53**	0.42**	0.39
Step 3				0.133	.011				0.047	.234
sAA (pre)	0.04	−0.03	−0.02			0.12	−0.02	0.07
SDNN (pre)	1.02*	0.27*	0.27			0.97*	0.04	0.25
RMSSD (pre)	−0.84*	0.17	−0.22			−0.77*	0. 01	−0.21
Step 4				0.003	.973				0.030	.433
sAA (RT)	−0.06	−0.09	−0.03			−0.05	−0.05	−0.03
SDNN (RT)	0.09	0.25*	0.03			0.58	0.07	−0.17
RMSSD (RT)	−0.04	0.15	−0.01			−0.48	0.09	0.16

*p<.05, **p<.01. r: Pearson correlation; sr: unique variance; SDNN: standard deviation of the normal RR intervals; RMSSD: HRV measure of parasympathetic activity. ERI: effort-reward imbalance; OC: overcommitment; sAA: salivary alpha-amylase. Total Simple RT model: R² = 0.207, F (9, 69) = 2.00, p = .052, Choice RT was R² = 0.257, F (9, 69) = 2.65, p = .011.

Figure 1. Illustration of the association between effort-reward imbalance (ERI) and choice reaction-time for those with low (n = 46) and high (n = 33) levels of salivary alpha-amylase (sAA) at pretest. Note: The ERI and sAA variables were mean-centered prior to moderation analysis, but we display the raw ERI, not the z-score in our illustration