Flanker Task

Background

The Eriksen Flanker Task is a classic cognitive test of executive control. Specifically, the Eriksen Flanker Task measures how well people can focus and respond to a central stimulus in the face of surrounding response-irrelevant stimuli that should be ignored.

The test was first developed by Barbara Eriksen and Charles Eriksen in 1974. In their research, Eriksen & Eriksen focused on the effect of irrelevant stimuli (called the 'noise') on target responses when the location of the target is fixed and known (as opposed to target search studies in which the target first has to be found). In their classic study, they asked participants to respond to two categories of letter stimuli: the 'round' category (consisting of letters C, S) and the 'edgy' category (consisting of letters H, K). One response behavior (a left lever) was dedicated to the 'round' category, and another response behavior (a right lever) was dedicated to the 'edgy' category. The relevant target letter was always the central letter on the screen, regardless of whether it was 'flanked' by irrelevant letters (e.g. H H H S H H H). By pairing the central letters with letters of the same and opposite category (as well as manipulating the distance between letters), Eriksen & Eriksen showed that the irrelevant letters influenced behavior: participants were faster when the target was flanked by letters from the same category (and required the same response: C C C S C C C), and they were slower when the target was flanked by letters from the opposite category (and required the opposite response: H H H S H H H).

The Eriksen Flanker Task was later simplified and streamlined by using left and right pointing arrows stimuli ('Arrow Flanker Task') instead of letters. For children, a fish-feeding game is played that uses left and right pointing Fish stimuli (Fish Flanker Task).

Task Procedure

Participants are tested in a mixed design that tests five different noise conditions x three different letter-spacing conditions. In all noise conditions, the central target letter is flanked by three letters on either side. The five noise conditions are:

1. The noise is equal to the target: e.g. HHHHHHH
2. The noise is the other letter from the target category: e.g. KKKHKKK
3. The noise is taken from the other category: e.g. SSSHSSS
4. The noise is similar to the target: e.g. NWZHNWZ
5. The noise dissimilar to the target: e.g. QJGHQJG

Additionally, two control conditions of no-noise targets are tested in a mixed vs. blocked design. For the mixed design, 4 no-noise trials are added to the testing of the five noise conditions. The blocked testing of the no-noise trials is run after the mixed blocks.

During each block, participants start each new trial by pressing the spacebar. Immediately, the stimuli appear and participants get a maximum of 1000ms to make their response: press left key 'Q' for 'H or K'; press right key 'P' for 'C or S'. Timed-out trials are not repeated in the implemented Millisecond procedure.

At the beginning of the testing session, participants work on one mixed block of practice trials. Error Feedback is provided only during the practice session. For the testing sessions, participants work through 6 rounds of testing: each round presents one mixed block of 32 trials and one no-noise block of 12 trials.

What it Measures

The Eriksen Flanker Task is a cognitive test to measure executive control in the form of response inhibition.

Psychological domains

• Executive Control: Ability to resolve conflict among competing stimuli, involving response inhibition and decision-making
• Inhibitory Control / Response Inhibition: Ability to override automatic/dominant responses that interfere with one's goals
• Selective Attention: Ability to select information from sensory input by directing attention to a specific location in space

Main Performance Metrics

• Accuracy Measures: Proportion correct responses in the varying noise conditions as a measure of conflict resolution success
• Latency Measures: Mean correct response times in the varying noise conditions as a measure of conflict resolution speed

Psychiatric Conditions

The Eriksen Flanker Task is mainly used for reseach purposes. General Flanker performance (usually measured with the Arrow Flanker Task) tends to be impaired in patients with the following conditions.

• Attention Deficit Hyperactivity Disorder (ADHD)
• Autism Spectrum Disorder (ASD)
• Schizophrenia
• Parkinson's Disease (PD)

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Flanker Task.

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Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143-149.

Ridderinkhof, K. R., van der Molen, M. W., Band, P. H., & Bashore, T. R. (1997). Sources of interference from irrelevant information: A developmental study. Journal of Experimental Child Psychology, 65, 315–341.

Cagigas, X.E., Filoteo, J.V., Stricker, J.L., Rilling, L.M., & Friedrich, F.J. (2007). Flanker compatibility effects in patients with Parkinson’s disease: Impact of target onset delay and trial-by-trial stimulus variation, Brain and Cognition, 63, 247-259.

Salthouse, T.A. (2010). Is flanker-based inhibition related to age? Identifying specific influences of individual differences on neurocognitive variables. Brain and Cognition, 73,51-61.

White, C.N., Ratcliff, R., & Starns, J.J. (2011). Diffusion models of the flanker task: Discrete versus gradual attentional selection. Cognitive Psychology, 63, 210-238.

Christ, S.E., Kester, L.E., Bodner, K.E. & Miles, J.H. (2011). Evidence for Selective Inhibitory Impairment in Individuals With Autism Spectrum Disorder. Neuropsychology, 25, 690–701.

Johnstone, S.J. & Galletta, D. (2012). Event-rate effects in the flanker task: ERPs and task performance in children with and without AD/HD. International Journal of Psychophysiology,

Luciana, M, Bjork, J.M, Nagel, B.J, Barch, D.M, Gonzalez, R, Nixon, S.J, & Banich, M.T. (2018). Adolescent neurocognitive development and impacts of substance use: Overview of the adolescent brain cognitive development (ABCD) baseline neurocognition battery. Developmental Cognitive Neuroscience, 32, 67-79.