2.1. Participants
A total of 63 healthy, undergraduates with a mean age of 19.46 years
(SD = 1.82, female = 36) were recruited for the present study.
All participants were prescreened using the State-Trait Anxiety
Inventory (T-AI score >45) and the Beck Depression
Inventory (BDI-II score > 15), as well as for abnormal BMI
(>28 or <18), regular intake of medicine, use of
hormonal contraceptives (current; female participants only), consumption
of alcohol or coffee, and existence of chronic or acute illnesses. Two
participants were excluded from the final analysis: one quit during the
stress induction procedure and another was withdrawn because of computer
failure. The final sample comprised 60 individuals (female = 31,M age=19.57, SD = 1.84) who met the
inclusion criteria and completed all the tests.
To determine sample size, a statistical power analysis was conducted
based on a medium effect size (Cohen’s f = 0.25), which suggested that
54 participants were required in order to detect the hypothesized effect
at α= 0.05 and β = 0.95. Participants provided written informed consent
and all procedures were conducted following the Declaration of Helsinki.
Prior to the experiment, participants were asked not to eat, exercise,
or consume caffeine for 2 hours. Randomly chosen groups of participants
were allocated to either the stress condition (n = 31) or the control
condition (n = 32).
The study pursued the principles of the Declaration of Helsinki (World
Medical Association, 2013) and was approved by the Academic Committee of
the Ministry of Education of the Key Laboratory of Modern Teaching
Technology, Shaanxi Normal University in China. Prior to the experiment,
all participants were required to provide written informed consent. And
each participant received payment as a token of appreciation for their
participation in the study.