1988'6, p.126
Loupandin V. I. , Augenberg I. V. , Ivanitchkina N. A. , Kozina L. Ye. , Shevtchenko S. A.
Visual and kinaesthetic estimation of sensory stimuli by children of different ages

In the study the data was obtained that junior children (5-7 years old) while estimating sensory stimuli and the difference in their strength use ordinal or interval scales more often. Later the relation scale gets developed which is based on the life experience of the subject and on his capacity for giving quantitative expression to interstimuli relations.