Furthermore, Ariely says, the likelihood that such essays contain plagiarism is high, stating, "We submitted the four essays to WriteCheck.com, a website that inspects papers for plagiarism and found that two of the papers were 35-39% copied from existing works."
WriteCheck is a service of iParadigms, the creators of Turnitin. WriteCheck is a service that, for a nominal fee, allows students to independently check their own papers for improper citations before turning them in for a class. It was developed with extensive input from educators who want students to be able take responsibility for checking their own work. WriteCheck compares submissions to the same database as Turnitin but does not add the papers to the Turnitin database and does not provide the specific source of the matched text, so students can't simply append their essays with quotes and false citations.