Previous studies conducted in the field of biological and evolutionary psychology tried to answer the question of the purpose and nature of yawning. One of the scientific explanations is that yawning has an important biological purpose for the organism and that it helps thermoregulatory processes in the brain. Thermoregulatory theory represents the starting point of the present experimental research conducted in the Laboratory for experimental psychology at the Department of Psychology at the University of Zadar. The aim of this research was to examine the effects of temperature on the incidence of contagious yawning. Experiment with independent groups gathered 30 male and 30 female participants that were placed in two experimental and one control group, and presented with a video showing 50 consecutive yawns. Experimental manipulation consisted of applying packs of low (9°C) and high temperature (46°C) on the participants' forehead, while the control group had a pack that was at the room temperature. In line with the initial hypothesis, results showed that cooling the forehead of the skull decreases the frequency of contagious yawning, compared with the control group and experimental group that had pack of high temperature, while there was no difference between the control group and the experimental group with high temperature pack. Differences considering gender were not significant. The results obtained in this study are in line with the thermoregulatory theory of yawning.