Tversky is a Perl module for running psychology experiments on the Web, especially (but not exclusively) on Amazon Mechanical Turk. You use it to write a CGI script in an imperative style that serves as the task. SQLite is used both for session management and to store the data subjects provide.

You should take the absence of documentation as a hint that I'm not making any guarantees about stability. I wrote this thing for my own use. But see Builder for an example task.

As for security, Tversky should resist SQL-injection attacks and cross-site request forgery, and I've tried to minimize race conditions. You should run your CGI script in taint mode, of course.

The rserve_call method requires the call method of Rserve::Connection that I defined in my fork of Rserve-perl.

Also included in this repository are:

schema.sql

A schema for the SQLite database.

add-conditions.pl

A Perl script to add values to the Conditions table in shuffled order. Use it to randomly assign conditions while controlling cell sizes.

mturk-tversky-reconcile.py

A Python script that checks that workers who completed your task really were the workers they claimed to be. See, MTurk has no means of authenticating Worker IDs, so Tversky simply records whatever Worker ID is claimed and leaves it to you to reconcile the database against MTurk. The code in Tversky that prevents workers from doing the same task twice will only screen out workers with reconciled completed assignments. This means that, yes, it is possible for anybody to do the task by faking their Worker ID, but once they've submitted the assignment, you can see the real Worker ID and reject it, so there's no point from their perspective. Anyway, before running this script, be sure to set the environment variable BOTO_MTURK_CLI to the location of the mturk program from my fork of boto.

test.pl

A test suite. Currently, it only tests Tversky's internal functions for parsing and doing arithmetic with units of measurement.

test-sqlite-sleeptimes.pl

A program that can be used to check if SQLite sleeps in whole-second increments, in which case Tversky may handle multiple simultaneous subjects badly. Pass it arguments like 2, 2.1, and 2.2 and watch the relationship between the parent's sleep time and the child's wait time.

See also Kodi.R for an R function unpack.tversky with which to import a Tversky database as a list of data frames.

Tversky is similar to but distinct from SchizoidPy, which is a Python module to run psychology experiments locally. Tversky and SchizoidPy have different APIs because of the fundamental differences between web programming and application programming (which I, unlike a lot of people these days, am hardly eager to smooth over), but I've tried not to make them needlessly inconsistent.

Tversky is named for Amos Tversky, who died for our economic sins and deserved the Nobel just as much as Kahneman, dangit.

License

This program is copyright 2012–2015 Kodi Arfer.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.