Graphical interface of the text length recognition program - Experiment 1. The program asked the experiment subjects to compare a variety of test texts, (left side) of length with another set of comparison texts (right side) of length . The subjects were asked to indicate which text is longer. When a right answer was given a new comparison text, with length closer to the test one (longer or shorter than it) was substituted. If a wrong answer was given or if the subject judged the texts lengths to be equal - which indicated that the difference was below the JND threshold - a new test text was drawn from the pool. The values were 20, 40, 50, 80, 100, 160, 200, 320, 400, 500, 640, 800, 1,000 and 1,280 characters, covering the spectrum from short sentences/sentence fragments to almost full page texts roughly uniformly on the logarithmic scale. All user answers were recorded in separate files for each tester, however the most interesting were those for which the subjects either considered them to be of equal length or ware unable to correctly determine the length relationships. These answers, denoted as represented length were gathered in a set of for each tester and for each test length .