Language
Divided Visual Field Task
Also called: visual half-field task, VHF task, divided visual field paradigm, DVF, lateralized lexical decision task, LLDT, hemifield word recognition, tachistoscopic word recognition
Measure the right visual field advantage for words: strings flash left or right of a cross for a word or made-up word decision, read across a group.
8-11 minTimed: desktop or laptop with a mouse or trackpad
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
- 64
- Evidence grade
- C
- Registered clinical studies
- 0
What it measures
Measures the right visual field advantage for words. Letter strings flash briefly to the left or right of a cross, and participants decide whether each is a real word or a made-up one. The advantage is read across a group, and the test cannot check where the eyes are.
Constructs
- Language lateralization
- Visual word recognition
- Hemispheric specialization
Research uses
- Language laterality research, at the group level
- Handedness and hemispheric specialization research
- Reading and bilingualism research
- Within-study group comparison
How the paradigm works
The divided visual field task measures the right visual field advantage for words, a behavioral sign that the left half of the brain handles language in most people (Hunter and Brysbaert, 2008; Hausmann and colleagues, 2019). Each half of the brain first receives what lies on the opposite side of where a person looks, so a word flashed to the right of the gaze reaches the left half directly. This form is a lexical decision with one string at a time, as in Iacoboni and Zaidel (1996) and in the browser experiments of Veldre and colleagues (2023).
More about the paradigm
On a dark panel a cross marks the middle. After 500 to 1,000 ms a string of 4 or 5 capitals flashes for 150 ms to the left or right of the cross, its inner edge 80 px from the middle; then hash marks cover its place, and the participant presses the key for a real word or for a made-up word within 2,000 ms. Which of F and J means word comes from the session ID, as in the Lexical Decision Task, so across a group each hand answers word equally often. The standard session has 4 parts of 68 trials. Each part shows each of 32 words and 32 made-up words once, half of each kind in each field, and the next part shows each item in the other field, so every item counts equally in both fields. In each part, 4 fixation checks with other items put a digit from 2 to 9 in the middle of the cross together with the string, and the participant types it afterwards. 8 practice trials with feedback come first. The displays switch on screen frames, and the measured wait and flash duration are saved.
The words are common nouns written for this task in English, German, Spanish, French, Italian and Portuguese, in letters A to Z only; the made-up words change one letter of other common words and were checked against word frequency lists of all six languages. Sessions in Chinese and Japanese show the English list, because the field advantage for characters depends on the script and the word form (Tzeng and colleagues, 1979; Hatta, 1977; Sasanuma and colleagues, 1977).
The main score is the right field advantage in time: the mean time of right answers to words in the left field minus the right field. Positive values mean faster recognition in the right field. Word accuracy in each field, the accuracy laterality index (R - L) / (R + L) x 100 of Hausmann and colleagues (2019), and d' in each field, which does not count a lean toward answering word as recognition, are reported too, with the share of fixation checks named. Fixation check trials are left out of the scores, and response times count right answers at or after 100 ms from the string.
Scores
- Right Field Advantagems
- Mean time of right answers to words in the left field minus the right field.
- Positive values mean faster recognition in the right field; read across a group
- Right Field Advantage, Mediansms
- The same from the median of each field.
- Positive values mean faster recognition in the right field
- Word Accuracy, Left Field%
- Share of words in the left field answered as words.
- Higher is better
- Word Accuracy, Right Field%
- Share of words in the right field answered as words.
- Higher is better
- Accuracy Laterality Indexscore
- Right word answers in the right field minus the left, over their sum, times 100.
- Positive values mean a right field advantage; -100 to 100
- Sensitivity, Left Fieldd'
- d' for words against made-up words in the left field, log-linear corrected.
- Higher is better
- Sensitivity, Right Fieldd'
- d' for words against made-up words in the right field, log-linear corrected.
- Higher is better
- Sensitivity Advantaged'
- Right field d' minus left field d'.
- Positive values mean a right field advantage not explained by a lean toward answering word
- Response Lean, Left Fieldz
- Criterion c in the left field.
- Negative leans toward answering word
- Response Lean, Right Fieldz
- Criterion c in the right field.
- Negative leans toward answering word
- Made-Up Word Accuracy, Left Field%
- Share of made-up words in the left field answered as made up.
- Higher is better
- Made-Up Word Accuracy, Right Field%
- Share of made-up words in the right field answered as made up.
- Higher is better
- Word Time, Left Fieldms
- Mean time of right answers to words in the left field.
- Lower is faster
- Word Time, Right Fieldms
- Mean time of right answers to words in the right field.
- Lower is faster
- Accuracy%
- Share of scored strings answered right.
- Higher is better; guessing gives 0.5
- Fixation Checks Named%
- Share of fixation checks on which the digit in the cross was typed correctly.
- Under half is flagged: the eyes may have left the cross
- Fixation Checkstrials
- Fixation checks answered.
- Informational
- Missed Stringscount
- Scored strings with no answer within 2,000 ms.
- Lower is better
- Anticipationscount
- Answers under 100 ms from the string's onset.
- Lower is better
- Keys Before the Stringcount
- Trials with F or J pressed before the string appeared.
- Lower is better
- Flash Durationms
- Median measured time the string was on the screen.
- Informational; the plan is 150 ms
- Frame Intervalms
- Median time between screen frames, about 16.7 ms on a 60 Hz screen.
- Informational
- Long Flashes%
- Share of strings shown a frame or more too long, a sign of missed screen frames.
- Over 10% is flagged
- Fewest Right Words in a Fieldtrials
- Right word answers in the field with fewer.
- Fewer than 10 is flagged
- Scored Trialstrials
- Trials in the scored run, fixation checks left out.
- Informational
- Total Trialstrials
- Trials in the scored run.
- Informational
Use and evidence
64 papers from 2021 to 2025 name this task in their title or abstract, down 33% compared with 2016 to 2020. That ranks it 274 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 13 |
| 2024 | 12 |
| 2023 | 12 |
| 2022 | 15 |
| 2021 | 12 |
| 2020 | 17 |
| 2019 | 16 |
| 2018 | 20 |
| 2017 | 22 |
| 2016 | 20 |
| 2015 | 24 |
| 2014 | 17 |
| 2013 | 26 |
| 2012 | 15 |
| 2011 | 32 |
| 2010 | 23 |
| 2009 | 25 |
| 2008 | 26 |
| 2007 | 22 |
| 2006 | 21 |
| 2005 | 13 |
| 2004 | 15 |
| 2003 | 24 |
| 2002 | 15 |
| 2001 | 18 |
| 2000 | 15 |
Use grade D
30 to 99 papers from 2021 to 2025.
Evidence grade C
At least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies.
- Papers on test-retest reliability
- 3
- Papers on reliability or validity
- 31
- 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.
- Display
- On a dark panel, a cross at the middle and a string of 4 or 5 capitals, 26 px bold, on its row, with its inner edge 80 px to the left or right of the middle.
- Wait
- 500 to 1,000 ms of the cross alone, drawn for each trial.
- Flash
- The string for 150 ms in whole screen frames, nine frames of a 60 Hz screen, then hash marks over its place until an answer or 2,000 ms from the string.
- Keys
- F and J for a real word and a made-up word. Which key means word comes from the session ID, as in the Lexical Decision Task, and is saved.
- Items
- 32 words and 32 made-up words, half of 4 letters and half of 5, written for this task in English, German, Spanish, French, Italian and Portuguese. Chinese and Japanese sessions show the English list.
- Parts
- 4 parts of 68 trials (standard; 2 parts with each item once in each field): each part shows every item once, half the words and half the made-up words in each field, and the next part shows each item in the other field. 256 scored trials.
- Fixation checks
- In each part, 4 trials with other items, a word and a made-up word in each field, also show a digit from 2 to 9 in the middle of the cross. Afterwards the participant types it, or presses the space bar after seeing none. These trials are left out of the scores.
- Order
- In each part, an order drawn from the session's seed with no more than three words, three made-up words or three strings on one side in a row.
- Practice
- 8 trials with their own items, 2 of them with a digit, with feedback for 800 ms. No feedback in the test.
- Score
- Mean time of right answers to words in the left field minus the right field. Also each field's accuracy and d', and the accuracy laterality index, (R - L) / (R + L) x 100 on right word answers.
The advantage is read across a group: one person's value is noisy, and these measures have shown moderate reliability (Voyer, 1998). The test cannot check where the eyes are. A participant who looks toward the side where the letters appear sees them near the middle of vision; the 150 ms flash and the numbers in the cross make this less likely but cannot rule it out (Parker and colleagues, 2021). The letters appear on whatever screen the participant has, so their distance in degrees varies between people. The scores support research and do not diagnose or say which half of the brain handles a person's language.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: divided_visual_field_test from the scored run, the fixation checks left out, F or J for a real word or a made-up word (chance 50%, half the strings are words) within 2,000 ms of the string, correctness from the key for the string. Below chance invalidates and not above chance is flagged. One key on 90% of answers invalidates when accuracy is not above chance. Missed responses and responses under 100 ms follow the timed-test rule. Fewer than 10 right word answers in either field, fewer than half the numbers named on the fixation checks, and letters shown a frame or more too long on over 10% of trials are flagged.
Why these rules
Accuracy significantly below chance (one-sided exact test, p < .05) cannot come from guessing; it means the response mapping was reversed or the task was not followed (Slick, Sherman and Iverson 1999 treat below-chance forced-choice performance as definite response bias). Chance-level accuracy can be a real result in impaired participants, so it is only flagged. One option on at least 90% of answered trials, when the correct options are balanced and accuracy is not above chance, means the answers did not depend on the items (the task counterpart of long-string responding in surveys; Curran 2016). Missed responses and responses under 100 ms keep the platform's timed-test rule: more than max(3, 25%) missed responses or more than max(2, 20%) responses under 100 ms invalidate, and any is flagged. A response under 100 ms cannot be a reaction to the stimulus. The advantage is a difference between two fields' mean times, so each needs enough right answers; the numbers in the cross show whether the eyes stayed on it, since the test cannot see them; and letters kept on the screen too long could be looked at directly. The limits of 10 answers, half the numbers and 10% of trials are ConductScience choices, the last two as in the Crossed-Uncrossed Difference Task.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Presentations per field | 2 (standard) | 1, 2 (standard) |
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
- Timed test: participants need a desktop or laptop with a mouse or trackpad. Participant devices
- Languages: English, Spanish, French, German, Italian and Portuguese (Brazil). Chinese (Simplified) and Japanese sessions use English words.
- 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 Divided Visual Field Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Iacoboni and Zaidel, 1996; Hausmann and colleagues, 2019), with the standard settings (presentations per field: 2). The main score was right field advantage (mean time of right answers to words in the left field minus the right field).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Iacoboni, M., & Zaidel, E. (1996). Hemispheric independence in word recognition: Evidence from unilateral and bilateral presentations. Brain and Language, 53(1), 121-140. https://doi.org/10.1006/brln.1996.0040Lexical decision with strings flashed in one field or in both: right-field words were recognized more often and faster.
- Bourne, V. J. (2006). The divided visual field paradigm: Methodological considerations. Laterality, 11(4), 373-393. https://doi.org/10.1080/13576500600633982Fixation control, one-sided presentation and methods of responding.
- Hunter, Z. R., & Brysbaert, M. (2008). Visual half-field experiments are a good measure of cerebral language dominance if used properly: Evidence from fMRI. Neuropsychologia, 46(1), 316-325. https://doi.org/10.1016/j.neuropsychologia.2007.07.007Flashes kept to 150 ms, short words, a mask, and information flashed at fixation.
- Willemin, J., Hausmann, M., Brysbaert, M., Dael, N., Chmetz, F., Fioravera, A., Gieruc, K., & Mohr, C. (2016). Stability of right visual field advantage in an international lateralized lexical decision task irrespective of participants' sex, handedness or bilingualism. Laterality, 21(4-6), 502-524. https://doi.org/10.1080/1357650X.2015.1130716A right-field advantage in accuracy, response time and d' in 100 participants.
- Hausmann, M., Brysbaert, M., van der Haegen, L., Lewald, J., Specht, K., Hirnstein, M., Willemin, J., Barton, J., Buchilly, D., Chmetz, F., Roch, M., Brederoo, S., Dael, N., & Mohr, C. (2019). Language lateralisation measured across linguistic and national boundaries. Cortex, 111, 134-147. https://doi.org/10.1016/j.cortex.2018.10.020The advantage in six languages and seven countries, and the accuracy laterality index.
- Veldre, A., Reichle, E. D., Yu, L., & Andrews, S. (2023). Understanding the visual constraints on lexical processing: New empirical and simulation results. Journal of Experimental Psychology: General, 152(3), 693-722. https://doi.org/10.1037/xge0001295Lateralized lexical decision run in a browser gave results close to a laboratory run with eye tracking.
- Parker, A. J., Woodhead, Z. V. J., Thompson, P. A., & Bishop, D. V. M. (2021). Assessing the reliability of an online behavioural laterality battery: A pre-registered study. Laterality, 26(4), 359-397. https://doi.org/10.1080/1357650X.2020.1859526A visual half-field task online, and why a browser cannot control eye movements.
- Voyer, D. (1998). On the reliability and validity of noninvasive laterality measures. Brain and Cognition, 36(2), 209-236. https://doi.org/10.1006/brcg.1997.0953Moderate reliability of laterality measures, so one person's value is read with care.
- Tzeng, O. J. L., Hung, D. L., Cotton, B., & Wang, W. S.-Y. (1979). Visual lateralisation effect in reading Chinese characters. Nature, 282(5738), 499-501. https://doi.org/10.1038/282499a0The field advantage for Chinese depends on the word form, one reason Chinese and Japanese sessions show English words.
Source papers
- Hausmann and colleagues (2019), Cortex, 111, 134-147, and Willemin and colleagues (2016), Laterality, 21(4-6), 502-524: the translingual lateralized lexical decision task.Paradigm source, Adults
Questions
How long does the Divided Visual Field Task take?
About 8 to 11 minutes, as listed in the test library.
What device does a participant need?
Timed test: participants need a desktop or laptop with a mouse or trackpad. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Right Field Advantage, Right Field Advantage, Medians, Word Accuracy, Left Field, Word Accuracy, Right Field, Accuracy Laterality Index, Sensitivity, Left Field, Sensitivity, Right Field, Sensitivity Advantage, Response Lean, Left Field, Response Lean, Right Field, Made-Up Word Accuracy, Left Field, Made-Up Word Accuracy, Right Field, Word Time, Left Field, Word Time, Right Field, Accuracy, Fixation Checks Named, Fixation Checks, Missed Strings, Anticipations, Keys Before the String, Flash Duration, Frame Interval, Long Flashes, Fewest Right Words in a Field, Scored Trials and Total Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Divided Visual Field Task used in research?
64 papers from 2021 to 2025 name it in their title or abstract, down 33% compared with 2016 to 2020. That ranks it 274 of 495 test families in the ConductCognition test census (use grade D). Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Divided Visual Field Task have?
In the published research, 3 papers report its test-retest reliability and 0 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Presentations per field (1, 2 (standard)). 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 and Portuguese (Brazil), with its words in the same language. In Chinese (Simplified) and Japanese, the instructions are translated and the words stay in English. 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.
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