An artwork's motifs define and constitute its content; they shape its theme and overall impression. This book focuses on the visual motifs that appear in interactive digital art. 'Interactive digital art' includes work equipped with digital sensors, internet-based pieces, pieces based on artificial intelligence (including genetic art), or pieces using telematics, voronoi diagrams or fractal rules. It also includes biological art and device art, and computer-graphics and animations in general, presented as video-installations, virtual-reality or augmented-reality installations. Interactive digital artworks are characterized by making the observers not only passive viewers, but also active co-authors of the work. Interacting with such artworks allows visitors to be part of a sophisticated process, to participate in changing and re/creating this process, or in exploring it using tools like joystick, mouse, or head-mounted display, or via specially created platforms. In some artworks, visitors can participate via non-material interfaces. Different research methods such as visual perception based on psychology, and established art historic comparative methods are put together to analyse these artworks. This book locates the interactive digital artworks in an art historic context, illustrating the character and development of pre-existing visual motifs from the palettes of Old Masters to contemporary interactive digital art.