LineDisc: A program for testing people's ability at horizontal line-length discrimination.

Vit Drga

Download the zipped archive here: LineDisc_v0.2.1.zip.

The program runs a single-interval forced-choice experiment involving the display of two horizontal lines on each trial. Your task is to say if the top line was the longer or the shorter than the bottom line. This can be run either as a 2-point rating scale (Yes/No) or as a 10-point rating scale. At the end of a set of trials, you get an ROC curve and summary measures of performance, and you can save results to file. For more details, run LineDisc and click the button "Experiment Information".

Although LineDisc was only written as an exercise while learning Delphi, you could use it as the basis for psychophysical experiments that use more complicated stimuli. I plan to reuse the ROC plotting code when upgrading data analysis programs from my thesis. [Later note: the *.dfm files were not included in the zip file by mistake and currently are inaccessible in N.Z. (while I'm in the U.K.), so recompilation is not possible. The *.pas files are present, however, and the executable works fine.]

The program was developed using Delphi 7.0 (Build 4.453) running on a Windows 32-bit platform. It is not a cross-platform program and as such is restricted to use under Windows.

Your mileage may vary... LineDisc has worked fine on PC workstations running Windows XP or ME, but there have been display problems on a laptop running XP. That's a very bland bug-description, but I'm not seriously pursuing development of the program. It's only an exercise for me, and you may not have any problems on your setup. Try it.

I like the GNU idea of free, open source software (see the GNU manifesto). The LineDisc program is copyright under the GNU Public License (see the source .pas files). This means you are free to modify the code as you wish and redistribute any program based on your modifications so long as you also make freely available your modified source code along with the program. There is README file in the zipped-up archive.

If you have any queries, please contact me using this form.

Last updated 12 Dec 2007 01:10 PM