What is the primary purpose of distractors in test questions?

The primary purpose of distractors in test questions is to discriminate between students who have a strong understanding of the material and those who may not. Effective distractors are designed to appear plausible to those who lack knowledge or understanding of the subject matter. This helps to assess a test-taker's depth of understanding and their ability to distinguish between correct and incorrect information.

Utilizing distractors effectively can reveal the nuances in a student’s grasp of the topic, as well as their critical thinking skills. A well-constructed question with appropriate distractors ensures that only those who have a true comprehension of the material are able to select the correct answer. Thus, options which lack this discriminative ability, such as those that simply confuse or filler options, do not fulfill the main purpose of effective assessment.