Episodic Memory
Bizarreness Effect Task
Also called: bizarreness effect paradigm, bizarre imagery task, bizarre imagery effect, bizarre sentences task, bizarre versus common sentences
Picture odd and ordinary sentences, then recall their words in a surprise test: words from odd sentences are recalled better, with the sentences written in each of the eight app languages.
8-11 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Try it here first, with no account.
- Papers, 2021 to 2025
- 6
- Evidence grade
- D
- Registered clinical studies
- 0
What it measures
Measures how much better odd material is remembered than ordinary material. Participants picture sentences, half odd and half ordinary, and rate how vivid each image is, then type the words in bold in a recall test they were not told about.
Constructs
- Distinctiveness
- Mental imagery
- Incidental encoding
- Free recall
- Episodic memory
Research uses
- Distinctiveness and memory research
- Mental imagery and encoding research
- Aging and memory research
How the paradigm works
The Bizarreness Effect Task measures how much better odd material is remembered than ordinary material, the bizarreness effect of McDaniel and Einstein (1986). Participants read 14 short sentences about animals and things, one at a time, and picture what each describes. Half describe something odd, such as "The yak plays the tuba", and half something ordinary, such as "The yak walks past the tuba". Each sentence names two things in bold, and the odd and the ordinary sentence of a pair name the same two things, so only what happens differs; two words to a sentence follow Riefer and Rouder (1992). Each sentence stays on the screen for 8 seconds, then a scale asks for 4 seconds how vivid the image was, from 1 (not at all vivid) to 5 (very vivid), as in the visual condition of Besken and Mulligan (2022). Odd and ordinary sentences are mixed in one list, with no more than 2 of a kind in a row, because the effect appears in mixed lists and not in lists of one kind. Nothing is said about memory: after 2 minutes of true-or-false arithmetic, a recall the participant was not told about asks for the words in bold, typed in any order on a visible timer, and a last question asks whether a memory test was expected. Two ordinary practice sentences come first.
More about the paradigm
The main score is the bizarreness effect: the share of the words of odd sentences recalled minus the share of the words of ordinary sentences recalled. Sentence access, the share of sentences with at least one of their words recalled, is reported for each kind too, with the mean vividness ratings. In the visual conditions of Besken and Mulligan (2022), with 8 odd and 8 ordinary sentences of three words each, noun recall was .37 to .39 after odd sentences and .24 to .26 after ordinary ones. The effect fades when odd and ordinary sentences are studied in separate lists, on recognition and cued-recall tests, and when the sentences are heard rather than read. The sentences and words were written for this task in each of the eight app languages; each session decides at random which 7 pairs are odd, so across sessions every word is studied in both kinds of sentence. With 14 words of each kind, one person's difference is noisy and is best used to compare groups. Scores support research and do not diagnose.
Scores
- Bizarreness Effect%
- Share of the words of odd sentences that were recalled, minus the share of the words of ordinary sentences that were recalled.
- Higher means more benefit from oddness
- Odd Sentence Words Recalled%
- Share of the 14 words of the odd sentences that were recalled.
- Higher is better
- Ordinary Sentence Words Recalled%
- Share of the 14 words of the ordinary sentences that were recalled.
- Higher is better
- Sentence Access Effect%
- Share of odd sentences with at least one of their two words recalled, minus the same share for ordinary sentences.
- Higher means more benefit from oddness
- Odd Sentences Accessed%
- Share of the 7 odd sentences with at least one of their two words recalled.
- Higher is better
- Ordinary Sentences Accessed%
- Share of the 7 ordinary sentences with at least one of their two words recalled.
- Higher is better
- Mean Vividness, Odd Sentencesscore
- Mean vividness rating, 1 to 5, of the images of the odd sentences.
- Context for the recall scores
- Mean Vividness, Ordinary Sentencesscore
- Mean vividness rating, 1 to 5, of the images of the ordinary sentences.
- Context for the recall scores
- Words Recalledcount
- Words of the 14 sentences recalled, of 28.
- Higher is better
- Intrusionscount
- Typed entries that name no word of the sentences.
- Lower is better
- Unrated Sentencescount
- Sentences whose vividness was not rated within the 4 seconds.
- Lower is better
- Expected a Memory Testflag
- 1 when the participant expected a memory test, 0 when not.
- 0 keeps the recall incidental
- Delay Arithmetic Accuracy%
- Share of the true-or-false arithmetic answered correctly in the delay.
- Shows the delay task was done
Use and evidence
6 papers from 2021 to 2025 name this task in their title or abstract. That ranks it 466 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 1 |
| 2024 | 0 |
| 2023 | 0 |
| 2022 | 0 |
| 2021 | 5 |
| 2020 | 0 |
| 2019 | 2 |
| 2018 | 2 |
| 2017 | 1 |
| 2016 | 3 |
| 2015 | 1 |
| 2014 | 2 |
| 2013 | 2 |
| 2012 | 4 |
| 2011 | 1 |
| 2010 | 0 |
| 2009 | 3 |
| 2008 | 1 |
| 2007 | 0 |
| 2006 | 3 |
| 2005 | 2 |
| 2004 | 0 |
| 2003 | 0 |
| 2002 | 1 |
| 2001 | 1 |
| 2000 | 5 |
Use grade E
Fewer than 30 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 0
- Papers on reliability or validity
- 1
- Registered clinical studies using it as an outcome
- 0
How the grades work
Use: A is 1,000 or more papers from 2021 to 2025, B 300 to 999, C 100 to 299, D 30 to 99 and E fewer than 30. Evidence: A means at least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome; B, at least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers; C, at least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies; D, little published measurement evidence found. The counts measure use. They include every paper that names the task in its title or abstract. Grades describe the published research on this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Sentences
- 14 sentences about animals and things, 7 odd and 7 ordinary in one mixed list, with no more than 2 of a kind in a row. Each names two things in bold; the odd and the ordinary sentence of a pair name the same two, and the session's seed picks which pairs are odd.
- Picturing
- Each sentence for 8 seconds, then 4 seconds to rate how vivid the image was on a 1 to 5 scale (1 not at all vivid, 5 very vivid), rated or not, and a 500 ms blank. Nothing is said about memory.
- Delay
- 120 seconds (standard; 30 to 300) of true-or-false arithmetic.
- Recall
- A recall the participant was not told about: the words in bold, typed one at a time in any order, for up to 180 seconds (standard; 60 to 600) on a visible timer, with a Done button. Then one question: was a memory test expected?
- Spelling
- Case, accents and punctuation are ignored, and plurals and other spellings count. In languages written in letters, one wrong, missing, extra or swapped letter is accepted in words of 4 or more letters unless the answer is another word of the language. In Japanese, kanji, hiragana and katakana count; in Chinese, simplified and traditional characters.
- Scores
- The bizarreness effect: the share of the words of odd sentences recalled minus the share of the words of ordinary sentences recalled. Sentence access (at least one word of a sentence recalled) and mean vividness for each kind are also reported.
- Practice
- 2 ordinary practice sentences, then the number rated in time.
The sentences and words were written for this task in eight languages; no published sentence set is used. The odd sentences are impossible or human actions, never violent, rude or about real people. The effect needs odd and ordinary sentences mixed in one list and recalled together. One person's difference rests on 14 words of each kind, so compare groups, not single people. The scores support research and do not diagnose.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: bizarre_sentences_rating rows of the 14 sentences from the scored run, one 1 to 5 rating each of how vivid the image of the sentence was, with no correct answer, with the recall, delay arithmetic and expectation rows of the same run. Fewer rating rows than planned invalidates. The same rating on 95% of 12 or more sentences is flagged. Ratings under 200 ms on at least half of 4 or more sentences invalidate, and any is flagged. More than a quarter of the sentences left unrated is flagged. A recall that was not saved, a recall with no word of the sentences, more typed words from outside the sentences than words of them (with at least 6 of them) and blocked pastes are flagged. A participant who expected a memory test is flagged. No arithmetic answered in the delay, or delay arithmetic at or below chance over at least 10 answers, is flagged. A hidden tab withholds the percentile.
Why these rules
There is no correct option to compare with chance, so accuracy is not judged against chance. The ratings ask the participant to picture each sentence; the same rating for nearly every sentence, or many sentences left unrated, means the sentences may not have been pictured. An answer under 200 ms is faster than a simple visual reaction, so it cannot reflect the item. Following response-time effort screening for untimed tests (Wise and Kong 2005), the session is invalid only when at least half the answers are that fast. The recall is incidental, as in the sources (McDaniel and Einstein 1986; Besken and Mulligan 2022), so an expected test is flagged. A recall with no word of the sentences gives a difference of 0 that may only mean the recall was skipped. Skipping the delay arithmetic means part of the procedure may not have been followed. A hidden tab lets the study, delay or response timers run without the participant, so a percentile is withheld after one.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Arithmetic before the recall (seconds) | 120 | 30 to 300 |
| Recall time (seconds) | 180 | 60 to 600 |
Yearly plans can change settings within these limits. Free and pay-as-you-go studies use the standard settings.
Need a setting this test does not have?
Devices and languages
- Untimed test: runs on desktops, laptops, tablets and phones. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- No percentile. Scores and quality flags only. How norms work
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Bizarreness Effect Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; McDaniel & Einstein, 1986; Besken & Mulligan, 2022), with the standard settings (arithmetic before the recall (seconds): 120; recall time (seconds): 180). The main score was bizarreness effect (share of the words of odd sentences that were recalled, minus the share of the words of ordinary sentences that were recalled).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- McDaniel, M. A., & Einstein, G. O. (1986). Bizarre imagery as an effective memory aid: The importance of distinctiveness. Journal of Experimental Psychology: Learning, Memory, and Cognition, 12(1), 54-65. https://doi.org/10.1037/0278-7393.12.1.54The paradigm: odd and ordinary sentences with the same words, and an advantage for odd ones in mixed lists only.
- Riefer, D. M., & Rouder, J. N. (1992). A multinomial modeling analysis of the mnemonic benefits of bizarre imagery. Memory & Cognition, 20(6), 601-611. https://doi.org/10.3758/BF03202710Two words to recall in each sentence, a mixed list of 6 and 6, and an incidental recall.
- Besken, M., & Mulligan, N. W. (2022). The bizarreness effect and visual imagery: No impact of concurrent visuo-spatial distractor tasks indicates little role for visual imagery. Journal of Experimental Psychology: Learning, Memory, and Cognition, 48(9), 1281-1295. https://doi.org/10.1037/xlm0001038Sentences for 8 seconds, then 4 seconds to rate vividness, no more than 2 of a kind in a row, two ordinary practice sentences and arithmetic before the recall.
- McDaniel, M. A., & Einstein, G. O. (1989). Sentence complexity eliminates the mnemonic advantage of bizarre imagery. Bulletin of the Psychonomic Society, 27(2), 117-120. https://doi.org/10.3758/BF03329915Why the sentences are kept simple.
Source papers
- McDaniel MA, Einstein GO (1986). Bizarre imagery as an effective memory aid: The importance of distinctiveness. Journal of Experimental Psychology: Learning, Memory, and Cognition, 12(1):54-65.Paradigm source
- Besken M, Mulligan NW (2022). The bizarreness effect and visual imagery: No impact of concurrent visuo-spatial distractor tasks indicates little role for visual imagery. Journal of Experimental Psychology: Learning, Memory, and Cognition, 48(9):1281-1295.Paradigm source, Young adults
Questions
How long does the Bizarreness Effect Task take?
About 8 to 11 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Bizarreness Effect, Odd Sentence Words Recalled, Ordinary Sentence Words Recalled, Sentence Access Effect, Odd Sentences Accessed, Ordinary Sentences Accessed, Mean Vividness, Odd Sentences, Mean Vividness, Ordinary Sentences, Words Recalled, Intrusions, Unrated Sentences, Expected a Memory Test and Delay Arithmetic Accuracy. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Bizarreness Effect Task used in research?
6 papers from 2021 to 2025 name it in their title or abstract. That ranks it 466 of 495 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Bizarreness Effect Task have?
In the published research, 0 papers report its test-retest reliability and 0 registered clinical studies use it as an outcome (evidence grade D in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Arithmetic before the recall (seconds) (30 to 300) and recall time (seconds) (60 to 600). Settings can be changed on yearly plans; free and pay-as-you-go studies use the standard settings.
Which languages can participants use?
Participants can take this test in English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese, with its words in the same language. English is on every plan, and the other languages come with yearly plans. Have a native speaker read the machine-translated text before launch.
Is this a clinical test?
No. ConductCognition is for research use only. It runs, scores and exports the test; clinical interpretation is outside the platform.
Every test: the full test list.
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