Letter-stimuli as targets were presented to the right or left visual fields and followed either by a flash of light or by a flash of light plus a patterned mask. The patterned mask always appeared in the opposite visual field of the letter targets. Analysis showed that masking occurred for both types of masks but that subjects produced more errors at each of five intervals between onset of the target and onset of the mask for the flash of light plus a patterned mask in the opposite visual field than for the flash of light alone. A pattern mask, when presented to the opposite visual field of a target stimulus, interferes with target processing at short target-mask intervals. These findings suggest that central backward masking may involve target-mask interactions beyond the visual cortex (Area 17).
Abstract
In the industry of manufacturing photo mask of Liquid Crystal Display (LCD) or Vacuum Florescent Display (VFD), there have been strong needs for a CAD system of fabricating a pattern mask directly from the CAD data of 2D mask design. This paper presents brief introductions to several algorithms and implementations used in the development of a CAD system for LCD/VFD mask fabrication. For the laser writer, it is simply required to provide the loop information of the pattern shapes. The ray casting algorithm is applied to derive this loop information from the CAD data composed of random vector list. For the photo plotter, the selection of the proper apertures and their plotting paths are derived to expose exact pattern shapes in the shortest time. The idea of Voronoi diagram is used to efficiently obtain an exact aperture path in this study. This paper also features some ideas for automatically detecting and fixing errors of designer’s drawing.
An experiment is described in which photographs of everyday objects were masked by frequency-filtered random visual noise. The masking functions obtained were of the same type as those obtained by masking letters and words with random noise or a pattern mask. That is, the high-frequency mask produced a type A function while the low-frequency mask produced a type B function. This result is discussed in terms of the general applicability of models of visual information processing constructed on the basis of experiments with letter or word stimuli. It is suggested that spatial-frequency concepts may usefully be employed to describe the relevant features of different types of mask.
U-shaped masking functions under backward masking by pattern mask