Figures & data
Figure 1. Experimental protocol.
Timeline depicting the experimental procedure. Participants’ saliva samples and subjective affective state (the Positive and Negative Affect Scale, PANAS) were collected four times throughout the task, i.e. baseline (3 min), during the CPT (3 min), 30 min after the CPT (3 min) and 55 min after the CPT. The token allocation task was completed within 25–37 min after CPT. In the token allocation task, participants were told that there were three players, a proposer “A” who was given an endowment of 100 monetary units (MU) and he/she was free to donate any proportion of this endowment to a recipient “B” who could only accept the proposal from A, and an unaffected third party “C” who had 50 MU and was asked to decide whether and how much to pay to deduct “A” and add “B,” any proportion donated by “C” would multiply by three to deduct “A”/add “B.” In reality, the offer between “A” and “B” was predetermined by a computer program with three possibilities, that was: 50 to A:50 to B, 70:30, 90:10, from fair to extremely unfair conditions.
Figure 2. Psychological and endocrinal measures.
Salivary cortisol concentration in the two groups (a); heart rate in the two groups (b); subjective negative affective state in the two groups (c). The results showed that the stress group (red line) have higher cortisol level, reported more negative feelings and exhibit higher heart rate than the control group (black line), these results confirmed that the stress effect was induced successfully in the present study. *p < .05; ***p < .001; error bars represent SEM.
Figure 3. Relationship of testosterone and prosocial preference under acute stress.
In the control condition, we found a significant interaction of testosterone × decision preference (a) and a significant interaction of testosterone × decision magnitude, which meant that individuals with low testosterone were more inclined to help than punish; however, individuals with high testosterone showed the opposite. In addition, we found a significant interaction of stress × decision preference (a) and a significant interaction of stress × decision type on the magnitude/intensity of the MUs transferred in the low-testosterone group. Which meant that acute stress reduced the helping preference (a) and increased the punishment magnitude (b) in individuals with low testosterone, while acute stress did not affect the preference of high-testosterone individuals. +p < .1; *p < .05; **p < .01; ns: not significant; error bars represent SEM.
Supplemental material