[The significance of the alerting tasks in the vestibular's caloric test]

To evaluate the vestibular's sensitivity to the stimulus of the cold and hot water.

Forty volunteers are randomly divided into four groups, group one for maths calculation, group two for answering the questions (they are active alerting groups) and group three and four for listening to music and to stories respectively (they are passive alerting groups). Each group has ten volunteers, their left ears are separately stimulated with the cold and hot water, recording the nystagmus slow phase velocity for 20 s at the highest level with the nystagmography instrument of HB-3 ENG computer treatment system.

There are significant differences between the two active alerting groups and the two passive ones (P < 0.01).

In performing the vestibular's caloric test, it's more reasonable for clinic to use active alerting tasks.