Effects of the Moderated Stress Exposure on the Short-Term Memory Capacity in Cadets

Abstract

Introduction. The effects of moderate-intensity stressors on short-term memory are studied, which is relevant to the professional training of first responders (firefighters) when preparing them for emergencies. This study investigates changes in the capacity of short-term memory under stress. Significant differences were found among memory parameters of fire cadets and students of civilian specialties. To the best of our knowledge, this is the first experimental study of the stress impact on the short-term memory capacity that takes into account professional education and training of the respondents. Methods. The study comprised 90 respondents, including 50 fire cadets of the Academy of State Fire Service and 40 students of Moscow universities. The subjects were divided into an experimental group and three control groups. Stressful stimuli (disturbing photo- and audio materials) were presented to respondents from two groups; respondents in two other groups were presented with neutral stimuli. The short-term memory capacity before and after the stressful stimulation was assessed with the Digit Span Test. The physiological signals of the subjects were measured during the experiment. Results. In fire cadets, stress resulted in a significant increase in memory capacity, while memory capacity showed a slight decrease in students. Physiological response to stressful conditions was different between students and fire cadets. Compared to cadets, the baseline muscle tension measures were higher in students. Compared to students, cardiovascular system parameters (systolic wave amplitude, pulse transit time) changed faster in cadets. However, these parameters changed not as substantially as those in students. Discussion. In fire cadets, memory capacity and its change due to stressful effects were associated with levels of non-verbal intelligence. It might also be mediated by emergency professionals' competencies. The system of selection, psychological training, and counseling of fire cadets in the Academy of State Fire Service is considered to be an important factor in the stability of cognitive functions under stress.