A. V. Ilgin. About the processes of concentration (attention) in the mentally ill. Experimental and psychological study of the mentally ill. Dissertation. From the psychological laboratory of Acad. V. M. Bekhterev. SPb. 1909

The author studied attention in the mentally ill four clinical forms: 1) dementia senilis, 2) dem. praec. 3) d. paralyt. and 4) paranoia. All patients were in the stage of clearly expressed dementia, but had not yet reached a deep degree. For the study, the author used the tables of Vaschide icons and tables of 6 letters, repeating without a certain order. The studied patients looked through the tables and marked the pre-defined symbols and letters. The number of viewed icons and letters measured the amount of work, and the % of incorrectly marked and missed ones indicated the quality of it, on the basis of which the conclusion about the state of attention was given.