The delay of the oculogravic illusion.

Previous measures of roll-tilt sensation during combined angular and linear acceleration during off-center rotation have found a heading-dependent delay in reaching a stable sensory value. This delay has been attributed to sensory conflict between the canal and otolith signals. Another possibility is that the visual indicator used to measure this sensation may have been responsible for the heading-dependent difference. This study used a somatosensory task, which is free from such artifacts and still showed a significant heading-dependent delay. We conclude that in analyzing canal-otolith interaction it is necessary to take into account the direction of the linear acceleration with respect to the activated canal.