The purpose of this project is to obtain data relevant to vestibular function and related oculomotor function in the human infant, child and adult. Such data will be obtained by quantitative measures of oculomotor response to several forms of stimulation: uniform angular acceleration (vestibular nystagmus); random instantaneous stepwise jumps of a light spot through varying degrees of ocular excursion (saccades); striped drum optokinetic stimulation (optakinetic nystagmus); and modification of vestibular nystagmus by exposure to prior rotation of a visual field (circularvection effects). The quantitative measures incude amplitudes, durations, and velocities of all eye movements. These parameters are measured for both the slow and fast components of all nystagmus responses. For vestibular nystagmus, the data are computed separately for the primary nystagmus and the secondary nystagmus. These data will be used to study the effect of age on these various parameters of vestibular nystagmus, to contrast such age effects with age effects on optakinetic nystagmus and saccadic eye movements, and to study the effect of age on the modification of vestibular nystagmus by retinal input due to circularvection. Biomathematical modeling of these data will attempt to refine and possibly modify the "torsion pendulum model" of vestibular nystagmus in order to bring the model into conformity with experimental data obtained in a developmental context. This will involve the use of advanced statistical techniques to develop equations accurately describing the time course of the nystagmus response.