A distractor is an incorrect option in a multiple-choice item. In a standard four-option MC item, there is one correct answer — the key — and three distractors. The quality of a multiple-choice test depends as much on the quality of its distractors as on the quality of its keys. Foil is an older synonym, still used in some psychometric writing.
A well-designed distractor is plausible but wrong. It should attract test-takers who lack the target knowledge or skill, while being clearly rejected by test-takers who possess it. The distractor must create a genuine choice: not trick the learner, but test whether they know the material.
Hughes (2003) notes that the key requirement is that distractors be definitely wrong but not obviously wrong. An obviously wrong option does not contribute to measurement: it effectively reduces the item to fewer choices, inflating the chance of guessing correctly.
| Problem | Example | Why it fails |
|---|---|---|
| Obviously wrong | In a reading comprehension item, an option that contradicts basic common sense | Everyone eliminates it; item becomes effectively 3-option |
| Too similar to key | Two options that are both arguably correct | Introduces construct-irrelevant difficulty: the item tests nitpicking, not comprehension |
| Grammatically inconsistent | Distractors that do not fit the sentence frame | Can be eliminated by grammar alone, without understanding the content |
| Length mismatch | The correct answer is significantly longer/shorter than distractors | Test-wise learners learn that the longest (or most qualified) option is often correct |
| Absurd | Clearly humorous or impossible options | Reduces effective choice; wastes test space |
| "All of the above" / "None of the above" | Formulaic options used to fill space | Often signals guessable patterns; limited diagnostic value |
Post-administration evaluation of how each option performed — endorsement rate, option discrimination, response distribution — has its own treatment in Distractor Analysis. The headline thresholds: each distractor should attract at least 5% of responses, and selecting it should correlate negatively with total score. Distractors that fail either criterion are reviewed and replaced, since they collapse the effective number of options on the item.
Base distractors on real learner errors. The best distractors come from error analysis of actual learner responses. If learners commonly confuse "affect" and "effect," that confusion makes an excellent distractor for a vocabulary item.
For reading comprehension: Distractors should reflect common misreadings: taking information from the wrong part of the text, confusing details with main ideas, misinterpreting reference words, falling for surface-level word matching.
For grammar: Distractors should reflect typical interlanguage errors at the target level: L1 transfer errors, overgeneralisation, developmental errors.
For vocabulary: Distractors should be semantically related to the key (same field, similar form, or common confusions), not random unrelated words.
Avoid "none of the above." Hughes (2003) argues against this option because it does not require the test-taker to know the right answer: only to know that the listed options are wrong.
Distractor quality directly affects test quality. Poor distractors:
In institutional test development, systematic attention to distractor quality — using error-analysis data, pretesting items, and running distractor analysis — is one of the most efficient ways to improve test quality.