Studies on optokinetic habituation.

Abstract

The question whether optokinetic nystagmus in humans can be habituated or not, has never been answered conclusively. In order to investigate this problem more closely, 15 healthy individuals, divided into 3 groups, have been exposed to repeated optokinetic stimulations of different direction and varying intensity. The velocity of the slow phase has been used as a parameter for the evaluation of the optokinetic response. Habituation of optokinetically induced nystagmus is not characterized by a response decline phenomenon, but on the contrary by an increase of the optokinetic response. Retention of this response increment has been confirmed as well as transfer from one side to the other. Repeated optokinetic stimulation has no influence upon the pattern of the caloric, galvanic and vestibulospinal responses of a test subject, i.e. there is no transfer from optic to vestibular responses. The increase of the optokinetic responses, following repeated optic stimulation, is not interpreted as a true habituation phenomenon, i.e. the simplest type of negative learning, but as the resultant of a process of positive learning.