Visual stimulation: effects on vestibular habituation

The influence of various forms of visual stimulation presented during the course of vestibular habituation to a caloric stimulus was studied. Eye movements which were either complementary or in opposition to the induced vestibular nystagmus were produced with an optokinetic drum. In addition, the effect of visual fixation during vestibular-response periods was studied. In all cases, the cats that received visual stimulation during the majority of the caloric trials habituated more slowly than did animals that received all the habituation trials in total darkness. These data conflict with previous reports of vestibular-visual interactions. Possible explanations for the discrepancy include species differences, distraction provided by the visual stimuli, and the transfer of learning from the dark to light conditions.