source: TED-Ed
2013年11月07日View full lesson: http://ed.ted.com/lessons/why-is-yawn...
*Yaaawwwwwn* Did just reading the word make you feel like yawning yourself? Known as contagious yawning, the reasons behind this phenomenon have been attributed to both the physiological and psychological. It's been observed in children as young as four and even in dogs! Claudia Aguirre visits the many intriguing theories that might explain contagious yawning.
Lesson by Claudia Aguirre, animation by TED-Ed.
