I've written a program which tests positive bias using Wason's procedure from "On the failure to eliminate hypotheses in a conceptual task" (Quarterly Journal of Experimental Psychology, 12: 129-140, 1960). If the user does not discover the correct rule, the program attempts to guess, based on the user's input, what rule the user did find, and explains the existence of the more general rule. The program then directs the user here.

I'd like to use a better set of triplets, and perhaps include more wrong rules. The program should be fairly flexible in this way.

I'd also like to set up a web-based front-end to the program, but I do not currently know any cgi.

I'm not completely happy with the program's textual output. It still feels a bit like the program is scolding the user at the end. Not quite sure how to fix this.

Program source

ETA: Here is a macintosh executable version of the program. I do not have any means to make an exe file, but if anyone does, I can host it.

If you're on Linux, I'm just going to assume you know what to do with a .cpp file =P

Here is a sample run of the program (if you're unfamiliar with positive bias, or the wason test, I'd really encourage you to try it yourself before reading):