Recent progress in the vestibular system has included research into vestibular function and clinical considerations. Vestibular Function Special interest has continued to be centered on the phenomenon of habituation as demonstrated in the vestibular system. Habituation or response decline are terms used here to indicate that one or several parameters of nystagmic reaction, such as duration of the reflex or velocity of the slow component, diminishes as vestibular stimulation is repeated. The experimental evidence indicates that habituation of vestibular reflexes is a central phenomenon presenting, as in a learning process, the characteristics of acquisition, retention, and transfer. The term "acquisition" stands for the progressive decrement of the nystagmic response. The extent of acquisition may range from moderate response decline to extinction. The term "retention" is used for indicating long-lasting persistence of the neural process underlying the response decline. It is the most important characteristic, because without retention the phenomenon of