The simple arrangement of seven letters revolutionized how scientists understand attention.
Imagine trying to focus on a single task while distractions surround you. This challenge, familiar in our modern world of constant notifications, lies at the heart of research begun decades ago by Charles W. Eriksen (1923-2018), a towering figure in experimental psychology. Alongside his wife and research partner Barbara Eriksen, he developed a deceptively simple experiment known as the flanker task in 1974 that would become one of the most influential paradigms in cognitive psychology3 7 .
Despite passing away in 2018, Eriksen's work continues to inspire contemporary research, with recent studies extending his concepts into exciting new domains like multisensory integration and cognitive neuroscience1 2 . His innovative methodologies and theoretical frameworks remain remarkably relevant today, with a special issue of Attention, Perception, & Psychophysics published in 2021 dedicated to contemporary developments inspired by his research1 6 .
Revolutionized understanding of attention and perception
Created one of psychology's most influential tasks
Work continues to shape modern neuroscience research
The original flanker task was elegant in its simplicity. Participants were shown arrays of seven letters and instructed to identify only the central target letter while ignoring the surrounding "flanker" letters2 . The critical manipulation lay in the relationship between these target and flanker letters.
Flankers identical to target or requiring same response
Flankers require opposite response from target
The groundbreaking finding was that reaction times were significantly slower when the flankers suggested a different response than when they suggested the same response2 7 . This interference effect occurred even though participants knew exactly where the target would appear and which letters to ignore, revealing fundamental limitations in our ability to filter out irrelevant information.
| Condition Type | Example Display | Target-Response Relationship |
|---|---|---|
| Congruent (Identical) | H H H H H H H | Same response |
| Congruent (Alternative) | K K K H K K K | Same response |
| Incongruent | S S S H S S S | Opposite response |
| Neutral (Similar) | G C G | No assigned response |
| Neutral (Dissimilar) | N C N | No assigned response |
| Target Alone | H | Baseline condition |
While the flanker task itself remains widely used, Eriksen's theoretical contributions have proven equally enduring:
Eriksen proposed that information processing isn't a series of discrete stages, but rather a continuous flow where partial information influences subsequent processing as it becomes available1 5 . This contrasted with the dominant stage-based models of his time and anticipated contemporary parallel processing models.
Recent research has revived interest in Eriksen's proposal that spatial selective attention operates in two distinct phases5 . During the initial non-selective phase, all stimuli in the display receive equal processing. This is followed by a selective phase where attention focuses exclusively on the target location.
Eriksen helped develop and test the influential metaphors of attention as either a spotlight that illuminates a fixed area or a zoom-lens that can adjust its breadth of focus3 . These concepts continue to guide research into how we allocate cognitive resources across space.
Recent research has extended Eriksen's primarily visual paradigm into multisensory domains2 9 . Studies now examine how auditory or tactile distractors influence visual target processing, and vice versa. For instance, visual target letters can be accompanied by irrelevant auditory letters, creating crossmodal congruence effects that operate similarly to traditional flanker interference1 .
These findings emphasize the importance of a multisensory perspective for understanding selective filtering and perceptual capacity limitations in real-world environments where distractions come through multiple senses simultaneously9 .
The flanker task has become a valuable tool in cognitive neuroscience for studying the neural mechanisms of cognitive control. Neuroimaging studies consistently identify the anterior cingulate cortex (ACC) as critically involved in detecting response conflict during incongruent trials7 . This brain region shows increased activity when participants process conflicting information from targets and flankers.
| Brain Region | Function in Flanker Tasks | Research Findings |
|---|---|---|
| Anterior Cingulate Cortex (ACC) | Conflict monitoring | More active during incongruent trials; believed to enhance cognitive control on subsequent trials |
| Prefrontal Cortex | Cognitive control | Implements adjustments to reduce interference after conflict detection |
| Visual Cortex | Early visual processing | Shows differences in how congruent and incongruent flankers are processed |
Research using the flanker task has revealed that our cognitive control systems are remarkably adaptive. The Gratton effect refers to the finding that interference from incongruent flankers is reduced following another incongruent trial compared to following a congruent trial7 . This suggests that experiencing conflict triggers adaptive mechanisms that improve subsequent performance, a phenomenon known as conflict adaptation.
A 2021 study by Mordkoff and Chen provides a compelling example of how Eriksen's ideas continue to inspire rigorous experimental testing5 . The researchers designed a series of experiments to test specific predictions derived from Eriksen's two-phase model of spatial attention.
| Experimental Finding | Interpretation | Theoretical Importance |
|---|---|---|
| Slower RTs on mixed control trials vs. blocked control trials | Proactive inhibition deployed when conflict possible | Supports strategic adaptive control mechanisms |
| Physiological evidence of early response activation suppression | Motor preparation begins but is inhibited | Confirms continuous flow with dynamic control |
| Distance-dependent interference effects | Attention can be focused more precisely with greater separation | Validates zoom-lens model of spatial attention |
All stimuli receive equal processing regardless of relevance
Attention narrows based on spatial location and task relevance
Processing focused exclusively on target location
Modern research inspired by Eriksen's work relies on a diverse set of methodological tools:
Provides precise measurements of overt visual attention and can distinguish between overt and covert attentional orienting2 .
Identifies brain regions involved in attention and cognitive control by measuring changes in blood flow7 .
Detects subtle muscle activation that may occur even when responses are suppressed, providing a sensitive measure of response competition5 .
Reaction time and accuracy data continue to provide fundamental insights into cognitive processes despite technological advances.
"Erik enabled us to see farther, and he illuminated paths for continued discovery"1 .
Charles Eriksen's legacy extends far beyond the specific paradigm he helped create. His insistence on methodological rigor, his development of converging operations to distinguish perceptual from response processes, and his innovative theoretical frameworks continue to guide the study of attention and perception3 .
Recent research has not only validated many of Eriksen's original insights but has expanded them in exciting new directions. The extension of flanker paradigms into multisensory domains reflects Eriksen's broader impact on how we study selective attention in rich, realistic environments rather than artificial laboratory settings2 9 .
Perhaps most importantly, Eriksen's work demonstrates the power of simple, elegant experimental designs to reveal profound truths about human cognition. As contemporary researchers continue to explore the implications of his theories using increasingly sophisticated tools, the flanker task remains a testament to his innovative spirit and enduring influence on cognitive science.
The contemporary developments inspired by his research ensure that this path remains bright with possibility.
Eriksen's work continues through: