Flanker Task: Meaning, Example, Scoring and Research

What is the flanker task? Meaning and origin

In psychology, the flanker task is a test of selective attention and interference control: focusing on one thing while ignoring nearby distractions that suggest a different answer. The items on each side of the target are called flankers.

The task comes from a 1974 paper by Barbara Eriksen and Charles Eriksen in Perception & Psychophysics, which is why it is often called the Eriksen flanker task. In their version, people identified a target letter while other letters, which they called noise letters, sat beside it. Letters linked to the other response slowed people down, even though they knew where the target would be.

In 2002, Jin Fan, Michael Posner and colleagues built the flanker task into the Attention Network Test (ANT). The ANT adds warning and location cues before the flanker display, so one 30-minute session estimates three things: alerting, orienting and executive attention. In 40 adults, the authors reported reliable single-person estimates and suggested that the three scores were not correlated with each other.

A flanker task example: congruent and incongruent trials

Most modern versions use arrows or simple pictures instead of letters. Here is what the trials in an arrow version look like. You press the key that matches the middle arrow:

• Congruent: → → → → →. Every arrow points right, so the flankers agree with the answer.
• Incongruent: ← ← → ← ←. The middle arrow points right, but the flankers point left.
• Neutral: — — → — —. The flankers are lines with no direction, used in some versions as a baseline.

How the flanker task is scored: the flanker effect

The main score is the congruency effect, also called the flanker effect or conflict score. It is the average reaction time on correct incongruent trials minus the average on correct congruent trials. A bigger number means the flankers slowed the person down more. Error rates are often compared the same way. In the ANT, this difference is the executive attention or conflict score.

Some standard versions combine speed and accuracy instead. The NIH Toolbox flanker test gives up to 5 points for accuracy and, for people above an 80% accuracy threshold, up to 5 more for reaction time, as Zelazo and colleagues described in 2014.

A flanker score is not a diagnosis. Norms depend on the exact version, age and equipment, so a number from one test cannot be compared with another. In 2018, Hedge, Powell and Sumner retested people on seven classic tasks, including the flanker, Stroop, go/no-go and stop-signal tasks. Test-retest reliability ranged from 0 to .82. The authors explained that the same low variation between people that makes these effects easy to replicate in groups makes the tasks less reliable for telling one person from another.

The NIH Toolbox Flanker Inhibitory Control and Attention Test

The NIH Toolbox, a set of brief measures for research and clinical studies, includes the Flanker Inhibitory Control and Attention Test. Its official page lists ages 4 and up, about 3 minutes, an iPad, and administration by an examiner with cognition access.

In the adult validation study, 268 healthy adults aged 20 to 85 took the test. It has an easier block with fish and a harder block with arrows, 25 trials each. A group of 73 retested 7 to 21 days later had an intraclass correlation of .83, which the authors rated excellent. In children, the authors reported excellent sensitivity to age and excellent reliability.

Researchers also use flanker tasks to compare groups. A 2009 systematic review included 12 studies of 272 children with ADHD and 280 without, and reported that the ADHD groups were slower and made more errors on incongruent trials relative to congruent ones. Results like these describe groups, not individuals.

Online flanker tests and flanker games

Many free online flanker tests run in a web browser. Researchers have tested how well browser versions work. In a 2013 study, Crump and colleagues repeated the flanker, Stroop and several other classic tasks with paid online workers on Amazon Mechanical Turk. Most results matched lab findings in pattern, though some tasks did not.

Timing is one limit. A 2021 study of four online experiment platforms found reasonable accuracy overall, but response times were recorded about 80 milliseconds late on average, up to about 100 milliseconds on some setups. That lag differs between computers and browsers, and phones and tablets were not tested. An online test gives a number for that sitting on that device. It is not the NIH Toolbox test and does not come with its norms.

Game versions dress the same rule in a story or picture. Lumosity said in a 2018 blog post that one of its games "is based on the 1974 Flanker Task." Our guide to brain training apps covers Lumosity and the FTC's 2016 order about its advertising.

Flanker task training: what practice studies found

Studies have trained children and adults on flanker-type and other inhibition tasks, then checked for transfer. Near transfer means gains on similar untrained tasks. Far transfer means gains on different skills such as intelligence, school or daily life.

Rueda and colleagues gave 4- and 6-year-olds five days of computer attention training, with 12 trained children in each experiment. The exercises included a Stroop-like conflict game, and a flanker-based child version of the ANT measured the outcome. The abstract reports more mature performance after training. In the full text, the authors wrote that the ANT data "do not provide sufficient evidence for a specific training effect" on conflict scores. Intelligence scores of trained 4-year-olds rose more than controls'. There was no long-term follow-up.

Thorell and colleagues gave preschoolers 5 weeks of computer inhibition training. Liu and colleagues later described that program as go/no-go, stop-signal and flanker tasks. Children improved on two of three trained tasks but did not improve on untrained inhibition, working memory or attention tasks compared with control groups.

In adults, Enge and colleagues ran a randomized, double-blind study of 122 young adults. Three weeks of adaptive go/no-go and stop-signal training did not differ from a non-adaptive active control at post-test or 4 months later, including on an untrained Stroop task and fluid intelligence. Across children's executive function training, Kassai's 2019 meta-analysis found near transfer (g = 0.44) but no significant transfer to untrained executive skills (g = 0.11). The authors said these results raise doubts about training one executive skill on its own. The 2016 review by Simons and colleagues, summarized in our visual brain training guide, reported a similar pattern across brain training programs.

Directionality: a flanker game with a binocular option

Directionality is the Optics Trainer game modeled on the flanker task. A flock of five birds appears, and you swipe the way the middle bird faces. The other four birds may face the same way, another way, or two different ways.

What it keeps is the core rule: answer for the centre item and ignore flankers that may point elsewhere. Flocks where the flankers agree and flocks where they disagree come in random order through the round.

What it changes:

• Birds instead of letters or arrows, and four directions (up, down, left and right) instead of two response keys. You answer with a swipe.
• The five birds come in seven layouts, including lines, a cross and V shapes, and the flock appears at different spots on the screen. Classic versions use a single row.
• There is no time limit on each answer. A round lasts 60 seconds, a right answer adds points and a wrong one takes some away. The game does not compute a flanker effect.
• It adds an optional binocular presentation. In 3D Glasses mode, each bird is drawn in a colour that only one eye sees through red-blue glasses on a phone, tablet or computer, or through the built-in display on Meta Quest. Depending on the setting, all the birds go to one eye, or the birds are split between the two eyes, while a thin grey ring around each bird is seen by both.

Where Optics Trainer fits

Optics Trainer is a set of vision and brain training games for iPhone, iPad, Android, web browsers and Meta Quest. Directionality is modeled on the flanker task and challenges you to respond to the middle bird while ignoring the others. It was not tested in any of the studies described here. It is not a measure or test, does not report a flanker effect, and is not a treatment or diagnosis. It is not FDA cleared. We make no claim that it changes attention, focus, IQ, school performance or memory. For clinical eye movement measurement, see our measurement product, Optics Tracker.

Optics Trainer is not a substitute for professional diagnosis or prescribed care. Consult your eye care professional for guidance about your specific condition. The phone and tablet apps start with a 7-day free trial, and a free web account includes 3 plays a day. After that, mobile and web access is $14.99 a month or $149.99 a year.

Frequently asked questions

Sources

1. Eriksen BA, Eriksen CW. Effects of noise letters upon the identification of a target letter in a nonsearch task. Percept Psychophys. 1974
2. Fan J, et al. Testing the efficiency and independence of attentional networks. J Cogn Neurosci. 2002
3. Zelazo PD, et al. NIH Toolbox Cognition Battery (CB): measuring executive function and attention. Monogr Soc Res Child Dev. 2013
4. Zelazo PD, et al. NIH Toolbox Cognition Battery (CB): validation of executive function measures in adults. J Int Neuropsychol Soc. 2014
5. NIH Toolbox. Flanker Inhibitory Control and Attention Test
6. Hedge C, Powell G, Sumner P. The reliability paradox: why robust cognitive tasks do not produce reliable individual differences. Behav Res Methods. 2018
7. Mullane JC, et al. Interference control in children with and without ADHD: a systematic review of Flanker and Simon task performance. Child Neuropsychol. 2009
8. Crump MJC, McDonnell JV, Gureckis TM. Evaluating Amazon's Mechanical Turk as a tool for experimental behavioral research. PLoS One. 2013
9. Anwyl-Irvine A, et al. Realistic precision and accuracy of online experiment platforms, web browsers, and devices. Behav Res Methods. 2021
10. Rueda MR, et al. Training, maturation, and genetic influences on the development of executive attention. PNAS. 2005
11. Thorell LB, et al. Training and transfer effects of executive functions in preschool children. Dev Sci. 2009
12. Liu Q, et al. The effects of inhibitory control training for preschoolers on reasoning ability and neural activity. Sci Rep. 2015
13. Enge S, et al. No evidence for true training and transfer effects after inhibitory control training in young healthy adults. J Exp Psychol Learn Mem Cogn. 2014
14. Kassai R, et al. A meta-analysis of the experimental evidence on the near- and far-transfer effects among children's executive function skills. Psychol Bull. 2019
15. Simons DJ, et al. Do "brain-training" programs work? Psychol Sci Public Interest. 2016
16. Lumosity. From lab to laptop: the origins of Lumosity games. 2018

Related guides

• Brain Games Backed by Science? The Lab Tasks Behind Them
• Stroop Test: The Stroop Effect, Experiment and Research
• Go/No-Go Task: Examples, Response Inhibition and Research
• Visual Brain Training: What It Is, What the Research Says, and How to Practice