Three experiments were conducted to determine whether the use of filler items in Rotter's I-E scale fulfills its stated objective of obscuring the purpose of the scale. Subjects were undergraduate psychology students. Experiment 1 compared the effects of filler items and sex of subject on 145 subjects I-E scores. Experiment 2 examined effects of filler items and sex on I-E responses of 210 subjects under standard and fake good instructions. Experiment 3 examined subjects' ability to discern the purpose of the I-E scale, with and without the filler items. Filler items did not affect I-E score, impede subjects from faking good, or obscure knowledge of the purpose of the I-E scale. Sex differences occurred in faking good, knowledge and certainty of correctness of knowledge.