The effect of maximal mouth opening on dimension discrimination

The ability of twenty-five young persons to discriminate dimensions was tested. A reference stick of 10 mm was placed between the teeth, alternating with test sticks of different heights. After application of the reference stick the subjects were asked to open the mouth maximally. A test stick was placed on the lower incisors and the subjects closed the mouth slowly, until their upper incisors contacted the test stick. The subjects were then asked to assess whether a test stick felt higher or lower than the reference stick. Using this experimental method, it was found that incorrect assessments were symmetrically distributed around the 10 mm reference stick. A receptor mechanism is proposed, and applied to explain the results of the present and a previous experiment.