All manifestations of dimensional harmony in nature and human practice are being always characterized by deviations from golden ratio that often makes their acceptance problematic. On the example of Fechner's experiments the paper discusses the way of solving this problem, based on informational approach, according to which the informatively optimal permissible deviation from dimensional harmony has been applied. The using of information optimization reveals that in experiment's data along with the phenomenon of the conformity of aesthetically preferred rectangle's sides' ratio with golden ratio the statistical majority attributed to the three most preferable rectangles should be regarded as the manifestation of the harmony in full accord with the permissible deviation from the golden ratio. Eventually the confidence to the harmony manifestation in regard to Fechner’s experiments is being significantly increased. The paper also focuses on the significance of the used investigation method and its influence onto research results.