Effectiveness of filler items in disguising scale purpose

Subjects (n = 246) were asked to identify the trait(s) measured by Rotter's Interpersonal Trust Scale with and without filler items, either by responding freely or by circling traits listed on a sheet. Half the subjects were informed prior to filling out the questionnaire that their task was to identify the traits being measured by the questionnaire; the remaining half of the subjects were informed of their task after they completed the questionnaire. Very few subjects were able to identify correctly the trait being measured by Rotter's scale regardless of the experimental condition. Most subjects named multiple traits. It was concluded that the use of filler items per se was not the key factor in disguising the true purpose of Rotter's test; rather item wording may have produced multiple interpretations.