Researchers admit participants to a study examining the effect of successful learning experiences on reported happiness among teenagers. Participants in the study are randomly assigned to engage in weekly learning sessions with varying levels of difficulty (either high or low) to generate different levels of success. Self-reported level of happiness of both groups is recorded at the end of the experiment. However, the tester that admitted one of the groups to the experiment did not properly explain the learning task that they needed to complete, which changed the difficulty of the task overall. What is TRUE about the results of the study