Biology Faculty Articles

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Physiology & Behavior


Brain temperature, Thermoregulation, Thermodynamic cooling, Adaptive behavior




The existence of yawning across a diverse array of species has led many researchers to postulate its neurological significance. One hypothesis, which has garnered recent support, posits that yawns function to cool the brain by flushing hyperthermic blood away from the skull while simultaneously introducing a cooler arterial supply. The current study tested this hypothesis by examining how manipulations aimed at modifying carotid artery temperature, which in turn directly alters cranial temperature, influences contagious yawning in humans. Participants held either a warm (46 °C), cold (4 °C) or room temperature (22 °C) pack firmly to their neck, just over their carotid arteries, for a period of five minutes prior to watching a contagious yawning stimulus. Thermographic imaging verified that these manipulations produced predicted changes in temperature at the superomedial orbital area, a region previously used as a noninvasive measure of brain temperature (i.e., the brain temperature tunnel). As predicted by past research, both the urge to yawn and overall yawn frequency significantly diminished in the cooling condition (p < .05). Less than half (48.5%) of the participants in the cooling condition reported the urge to yawn, while this urge was expressed by the vast majority of participants in the warming condition (84.8%). Moreover, there was a threefold difference in the mean number of yawns per participant between the cooling and warming conditions (0.364 compared to 1.121). These findings are consistent with previous research indicating that yawns function as a compensatory brain cooling mechanism.


The authors would like to thank Gillian Perry for assistance in processing some of the data from this report. ACG received funding for this research from the College of Arts & Sciences at SUNY Polytechnic Institute.





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