ONLINE CONTROL OF MOVING MASKS AND WINDOWS ON A COMPLEX BACKGROUND USING THE ATVISTA VIDEOGRAPHICS ADAPTER

In reading research, the moving mask and moving window paradigms have proved to be invaluable in determining the chronometric and spatial ch aracteristics of processing written text. The success of these methods has lead to a demand for their application in research on real-world scene perception. However, we will argue that the technical implementa tion of eye-contingent mask (window) movement across a stable text can not be applied to scene research. A new technique is proposed that all ows graphical masks or windows of arbitrary form, size, and content to be moved quickly over a complex graphical stimulus. This moving overl ay technique makes use of the ATVista graphics adapter, a board with t he ability to mix an internally stored and an externally generated ima ge into one composite image. A high-performance moving mask or window is created by programming the internal image to be movable and partly transparent. The technique is implemented on a standard personal compu ter interfaced with an eyetracker, thus bringing mask (window) movemen t under online eye-movement control. We discuss general principles of the technique and illustrate them with performance data from a concret e experimental setup.