Compared with a standard photographic/optical tachistoscope, a video tachistoscope would have more flexibility in image creation, storage, and presentation. However, standard video frame rates do not give sufficient temporal resolution in experimental displays. Dr. Thomas will build and test a video tachistoscope capable of 500 frames per second, 512 x 512 pixels per frame, and 8-bits per pixel. At 500 frames per second, the temporal resolution is one frame interval or 2 milliseconds which is necessary for perceptual experiments using tachistoscopic presentations in the study of spatiotemporal response characteristics or motion. The fast display system will consist of a specially designed monitor with P167 phosphor, a controller with image memory, and an interface to a microcomputer. The controller memory module will store from 1 to 1238 images which could be generated by the computer or selected from a library of stimulus images. The display sequence will be programmable so that each of the stored images can be displayed for a specified number of video frames. In Phase I, Dr. Thomas will build the first instrument and test its electronic and optical characteristics. In Phase II, he plans to conduct experiments using both the currently-standard tachistoscope and the new instrument, then proceed to use the video tachistoscope in various experiments in visual perception and aging, as well as develop software for efficient use of the highly flexible and powerful instrument. After the first unit, the new instrument should be relatively inexpensive and affordable by many research labs, academic departments, and vision testing labs.
