A tachistoscope is a device that displays (usually by projecting) an image for a specific amount of time. It can be used to increase recognition speed, to show something too fast to be consciously recognized, or to test which elements of an image are memorable. Some call this subliminal messaging. Swiftword is a version of a text based tachistoscope application. Essentially it is a speed reader - you feed it a text file containing the content you want to memorise, and play the file through at progressively faster speeds. Eventually, your subconscious begins to anticipate the next word before it is even delivered as your memory begins to retain the information. This can be used to help you memorise things like speeches and course notes, and can even assist slow readers to speed up through coaching to avoid sub-vocalising words as you read.