Psychophysiology represents a set of the sympathetic nervous system responses related to human behavior and mental activity. Its measurement most often consists of monitoring the cardiovascular system, electrodermal activity, breathing and the skin temperature. The monitoring of physiological changes is based on a comparison of the physiological state during stimulus presentation or task solving with the baseline physiological state. The more relaxed a measured individual is, the greater the potential the stimulus has triggering a physiological change. The master's thesis examines the question of what should the instructions to the participants of psychophysiological studies be to reasonably expect that they are in the most relaxed baseline state. Four different conditions of achieving the most optimal baseline after solving arithmetic tasks for some time were tested: relaxing in silence, watching the dot on the screen, watching the floating fishes on the screen, and playing a pong game on the computer. We monitored in each condition when the electrodermal activity and the number of its spikes will be the lowest and under which condition the temperature will be the highest, characterizing the most relaxing condition. Playing the pong game was not an appropriate condition for reaching the perfect baseline, most probably because of the mental-motor coordination that caused excessive arousal, while the other three conditions did not result in different physiological changes. These findings could indicate that the content of the instructions for reaching the baseline is not relevant, but could also raise a new question as to why differences did not occur, and could encourage new research to find the most appropriate method for reaching the perfect baseline in psychophysiological studies.