Visual Illusions by Matthew Luckiesh is about vision, physics, and the ability to see. You will enjoy reading about a variety of causes, characteristics, and applications of visual illusions. Contents: "The Eye, Vision, Some types of geometrical illusions, Equivocal figures, The influence of angles..."

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

"An unabridged and unaltered republication of the work originally published ... in 1922." Bibliography: p. 246-247.

The four-volume set LNCS 6765-6768 constitutes the refereed proceedings of the 6th International Conference on Universal Access in Human-Computer Interaction, UAHCI 2011, held as Part of HCI International 2011, in Orlando, FL, USA, in July 2011, jointly with 10 other conferences addressing the latest research and development efforts and highlighting the human aspects of design and use of computing systems. The 47 revised papers included in the third volume were carefully reviewed and selected from numerous submissions. The papers are organized in the following topical sections: universal access in the mobile context; ambient assisted living and smart environments; driving and interaction; interactive technologies in the physical and built environment.