8 directions the response keys are geographically arranged on a numeric keypad. For reliable results please observe the checklist. Your feedback is welcome and has frequently lead to improvements and extensions. If the on-line version of FrACT right below is blocked by your browser: consider iso 9613 2 pdf Flash on this page.
The downloadable stand-alone versions work independent of a browser. Optotypes include Landolt ring, tumbling E, Sloan letters, and faces. At the high end, acuities beyond 2. For an overview see this English introduction or eine deutsche Einführung. Make certain that the best possible color depth is chosen. Older versions of FrACT remain available and run just fine on older equipment. And please cite it when you’ve used it in scientific settings.
If you used FrACT for your research, please cite it. Be sure to have enough distance from the screen, so pixel resolution does not limit acuity. But see below for a cautionary note on the difficulties of contrast testing. All selections in SETTINGS are automatically saved. Enter the position of the appearing Landolt-C’s gap via the numerical digit keys. Response box Working with patients you may want to enter results yourself. In lengthy vision experiments, subjects are used to enter responses themselves.
For direct response entry by the subject, these keypads are useful. Most have only a short cable, for remote entry you will want to add a USB extension cable. This one even sports fancy labels. The Tumbling E has possible 4 orientations, the Landolt-C allows 4 or 8.
Why are all these numbers divisible by 6? 3 times its current threshold estimate. SETTINGS state is stored per FrACT file. IP-based result transmission is also available, using a standard URL-request GET call. What is special about the Contrast Test? Experience taught me that contrast testing is technically much more demanding than acuity testing. Unlike in acuity testing, the time taken to inspect the optotype plays a sizable role.
Macintosh platform, this is now addressed via dithering . 8-bit screen depth, they only have a 6-bit screen depth and overcome this by dithering themselves. So be sure you have an 8-bit screen, be it LCD, CRT, or OLED. In such conditions, high-quality front surface mirrors can be employed. Hundreds of studies have employed FrACT. Only occasionally do I find the time to systematically analyse the papers whether FrACT was actually used, so the list is incomplete.