Full-scale saccade-based display: public / private image presentation based on gaze-contingent visual illusion

Pursuing new display techniques based on insights of human visual perception can open up new possibilities for visual information presentation. Here we present the vast refinement of an information display method, which we call a saccade-based display. The saccade-based display can show two-dimensional (2D) images without any screen using only a single line of flickering light emitting diodes (LEDs). The following principle is fundamental to the implementation of this display. It is known that mechanical high-speed movement of a one-dimensional flickering LED array can present 2D images through retinal afterimages (this kind of visual display is commercially available [IMS 2000]) Conversely, when light sources are fixed on a vertical line, and the flashing pattern is changed quickly during a horizontal rapid eye movement called a saccade, 2D images can also be perceived due to spatio-temporal integration in the human vision system as in fig. 1(a). When a vertical line of lights flashes quickly during the horizontal saccade, the flashing pattern is expanded into a spatial pattern by the eye movement. During the eye movement, the vertical light array travels on the retina while changing the flashing pattern. Then, the different vertical images at different retinal locations are integrated into a 2D image as in fig. 1(b). Although the images presented during the saccade can hardly be seen in daily life (e.g. [Latour 1962]), the images with high contrast and high spatial frequency as presented with this display can be recognized [Watanabe et al. 2005b][Watanabe et al. 2005a].