The Localization of a Stimulus on Cornea and Conjunctiva

Abstract

A stimulus can be evaluated not only for its quality and intensity but also for its location. We tested the ability to localize the stimulus under suprathreshold conditions on none fixed points. We tested eight subjects and the points were stimulated in a random sequence. The subject then drew on a large sketch of an eye the location of the point touched. In Fig. 40 the heavy symbols are the prechosen test points and the small symbols are the average response by the individual subjects. The deviations between the true location and the one indicated by the subject increase in horizontal direction from the center temporally and nasally; in general, the sensations are localized more peripherally than would correspond to the actual location. In the horizontal meridian significant error in localization occurred only close to the limbus in the points 5 and 7 of the conjunctiva. In the vertical meridian the deviation is usually upward and significant is only the erroneous localization of a stimulus in the center of the cornea.