Manipulating neck temperature alters contagious yawning in humans

Area of Science:

• Neuroscience
• Physiology
• Behavioral Science

Background:

• Yawning is observed across many species, suggesting a significant neurological function.
• A leading hypothesis proposes yawning cools the brain by circulating blood.
• This study investigates the brain cooling mechanism of yawning.

Purpose of the Study:

• To test the hypothesis that yawning functions as a brain cooling mechanism.
• To examine the influence of altered carotid artery temperature on contagious yawning.
• To determine if manipulating cranial blood flow affects the urge to yawn.

Main Methods:

• Participants applied warm, cold, or room-temperature packs to their neck over carotid arteries.
• Thermographic imaging confirmed temperature changes in the orbital area, a proxy for brain temperature.
• Contagious yawning stimuli were presented after temperature manipulation.

Main Results:

• Cooling the carotid arteries significantly reduced both the urge to yawn and yawn frequency.
• Only 48.5% of participants in the cooling condition felt the urge to yawn, versus 84.8% in the warming condition.
• The mean number of yawns was threefold higher in the warming condition compared to the cooling condition.

Conclusions:

• Findings support the theory that yawning serves as a compensatory brain cooling mechanism.
• Carotid artery temperature manipulation effectively influences contagious yawning behavior.
• This research provides empirical evidence for the thermoregulatory role of yawning.