Uncertain Drop vs. Socially Evaluated Cold Pressor: Uncertain Stress Elicits Stronger Psychophysiological Responses...

This study developed the Uncertain Drop Stress Test (UDST), an uncertain stress induction paradigm based on the high survival-relevant threat of fear of falling, wherein neither the occurrence nor the timing of the fall is predictable. The aim was to compare its stress induction efficacy and neural oscillatory changes with those of the Socially Evaluated Cold Pressor Test (SECPT), a certain stress paradigm, and to examine gender differences.

Forty-eight participants (24 males; 24 females) were recruited. Psychological indicators (subjective stress, negative affect, and state anxiety) and physiological indicators (heart rate, heart rate variability, galvanic skin response, and salivary cortisol) were measured before and after stress to compare induction efficacy. Resting-state EEG was collected for frequency domain analysis to explore neural oscillatory changes.

UDST induced more pronounced psychophysiological changes. Notably, only UDST significantly decreased heart rate variability and increased galvanic skin response. UDST triggered an "exogenous vigilance mode" characterized by enhanced high-frequency (Beta/Gamma) activity, whereas SECPT elicited an "interoceptive focusing mode" characterized by suppressed low-frequency (Theta/Alpha) activity. Females exhibited higher heart rate and Beta activity than males under both stress conditions.

UDST elicits stronger psychophysiological responses and distinct neural oscillatory patterns, with females showing greater stress reactivity.