What is the primary purpose of distractors in multiple choice questions?

The primary purpose of distractors in multiple choice questions is to discriminate between students who have a solid grasp of the material and those who do not. By including distractors that are plausible but incorrect, test creators can evaluate the test-taker's understanding of the concepts being assessed. Effective distractors will draw on common misconceptions or closely related ideas that a student might confuse with the correct answer, thus allowing educators to gauge not just recall, but comprehension and critical thinking skills.

Including distractors that make sense to someone who may not have mastered the content helps to reveal the level of understanding a student has. If a student can identify the correct choice among well-crafted distractors, it demonstrates their knowledge and ability to navigate through similar concepts in real-world applications. This reduces reliance on guessing and provides a more accurate measure of a student's knowledge.