嚏、欠、唾、涎是记载人生理现象的常用词,演变有喷嚏、呵欠、唾沫、涎唾、口水、哈欠等复音词。打喷嚏与打呵欠在作为人不由自主的生理现象上有相似处,但打喷嚏由外界刺激而引发,打呵欠由疲倦而引发。流涎唾也是人不由自主的行为,吐唾沫则是人可以自主的行为。就人的认知心理而言,打喷嚏是人受外界刺激不由自主产生的生理现象,故用唾来禳解嚏或驱邪镇鬼可以说是人们以自主行为制约不自主行为或外敌的一种表现,后渐演变成为一种人为附会的习俗义。
To Sneeze and to yawn have the similarity concerning the involuntary physiology although to sneeze is aroused by the motivation from outside world while to yawn is caused by weariness. Salivation is also an involuntary behavior while spitting is an independent behavior. Regarding people' s recognizing psychology, to sneeze is an involuntary physiology phenomenon caused by outside world. Therefore, spitting, used for blessing or avoiding ghosts, is a demonstration of people using independent behaviors to restrict spontaneous behavior or enemies from outside which developed a kind Of accustomed meanings added by people.