The present study investigates the onset latencies for linear vection along both the spinal and the sagittal axis in erect human adults. For each axis, both directions have been investigated (upward vs downward, forward vs backward). The vection-onset latency is thought to be shortened by the decrease of the conflict between visual and vestibular afferents. Since this sensory conflict can be presumed to be more important in the horizontal sagittal axis than in the vertical spinal one, the vection-onset latencies have been hypothesised to be longer in the former case than in the latter. Additionally, since the magnitude of this sensory conflict can be presumed to be the same between the two opposite directions within each axis, the vection-onset latencies have been expected not to vary between directions within each axis. The results confirm both these hypotheses.