Previous research was mainly focused on comparing deontological and utilitarian decisions in moral dilemmas, and their physiological changes. Generally, the results of these studies confirm that the level of physiological variables, i.e. the variability of cardiac R-R intervals, in moral reasoning and decision-making changes depending on the difficulty of the dilemma and the level of the actor's involvement. The obtained differences are primarily attributed to the dominance of the cognitive or emotional component. Consequently, the aim of this study was to examine changes in heart activity and some aspects of the decision in moral decision-making situations that differed with regard to the severity of the consequences for the offender and the degree of responsibility for the assessors/participants (with/without the presence of other witnesses). 33 students from the University of Zadar participated in the research, and the experiment included the presentation of two, rotated-by-case, hypothetical scenarios that show the violation of academic ethical principles (with different severity of consequences for the actor). After reading the scenario, the task was to answer whether they would report the offender and assess the certainty of the decision if they were the only witness, and if there were other witnesses. During the entire test, the length of the R-R interval was recorded for the participants, as well as the rest time preceding each experimental situation. It was determined that participants report a friend/colleague more often when the consequences are less severe and they cannot shift the responsibility to someone else (without other witnesses present) than in other situations. No differences were recorded in the certainty of the decision. The decision time is significantly longer only when the consequences for the offender are less severe and the offense was witnessed by other people. Slower decision-making seems to be caused by the reconsideration of the decision in participants who decided to report the violation. Although there was a decrease in cardiac variability parameters in scenario reading situations and during decision-making compared to the rest period, no differences were found in the values of the recorded cardiac activity parameters (MRR, SdRR, RMSSD, LF, HF, LF/HF) with regard to consequence severity for the offender.