Magnitude estimation of oral cavity distances

Adult subjects were asked to estimate relative distances between points marked on artificial palates fitted to their own palatal vaults. The artificial palates were less than 1 mm thick and extended posteriorly along the hard palate from the central incisors to approximately the second molars. Distances of 4, 8, 12, 16, and 20 mm were marked on four planes on the palates, one corresponding to the alveolar ridge, one anterior and two posterior to the ridge. The subjects felt raised points on the palates with their tongues and assigned number referenced to a standard distance on the alveolar plane. The eight adults performed the task very reliably, and the growth of scores corresponded closely to the increases in distance among the points judged. Accuracy did not vary with the particular plane, and performance was as accurate on the first trial as it was on the fifth. These subjects displayed very precise proprioceptive-kinesthetic knowledge of the oral cavity.