Charles W. Eriksen

Introduction

Charles W. Eriksen (4 February 1923 – 16 February 2018), known to colleagues as "Erik," was one of the most influential experimental psychologists of the twentieth century. Working mainly on visual information processing, he invented or helped establish several methods now taken for granted in attention research, most famously the flankers task he developed with his wife Barbara A. Eriksen in 1974. He was the founding editor of Perception & Psychophysics and served as its principal editor for twenty-three years, shaping the standards of an entire field. His 1979 continuous flow model, developed with David Schultz, challenged the discrete-stage orthodoxy of the day and anticipated later diffusion and accumulator models of speeded decision.

Early Life and Education

Eriksen was born in Omaha, Nebraska, and graduated from the University of Omaha in 1943. He enlisted in the U.S. Army, declining officer training and stateside service to join the combat infantry. He landed in Normandy a month after D-Day, fought across Europe and received multiple medals for bravery, though like many of his generation he did not talk about them afterwards.

One incident from the period was recounted by his colleagues. Stationed briefly at Fort Bragg, North Carolina, Eriksen refused to obey a drinking fountain sign reading "Colored Only," telling friends he could not honour racist restrictions he had just risked his life fighting in Germany. He spent the night in jail and was released the next morning by his commanding officer.

Supported by the G.I. Bill, he enrolled at Stanford University in 1946 for graduate study in psychology. He considered physics but, by his own account, the enrolment line was shorter for psychology. He trained as a research-oriented clinical psychologist under Maud Merrill James, and completed his doctorate in 1950 with a thesis on perceptual defence, "Perceptual Defense as a Function of Unacceptable Needs," published the following year in the Journal of Abnormal and Social Psychology. He later described those first experiments on unconscious perception as extremely naïve.

Academic and Professional Career

Wendell Garner recruited Eriksen to the Johns Hopkins University psychology department in 1950, partly to run the student psychological clinic and partly to contribute to research on perception and performance. Eriksen credited Garner with training him as an experimental psychologist, and his work at Hopkins turned toward two problems that preoccupied him for the rest of his career: whether perception can occur without awareness, and how stimulus and response uncertainty affect human performance.

He later moved to the University of Illinois at Urbana-Champaign, where he spent the remainder of his career. He authored more than 150 scientific articles, and his fifty most cited papers have been cited over 20,000 times.

Eriksen founded Perception & Psychophysics and served as its principal editor from 1971 to 1993, twenty-three years, making him the longest-serving editor in the journal's history and one of the most consequential gatekeepers in experimental psychology. When he retired in 1993 he held the longest continuously funded research grant in the entire National Institutes of Health, and he was the last recipient of an NIH Research Career Award.

He died at his farm in Oakland, Illinois, on 16 February 2018, at the age of 95, with his wife Barbara and daughter Kathy at his side.

Major Contributions to Psychology

Perception without awareness

Before turning to attention, Eriksen conducted some of the most careful methodological work on subliminal perception. Across the 1950s and 1960s he and his students subjected claims of perception without awareness to experimental analysis and showed repeatedly that they rested on methodological and conceptual errors, chiefly the use of insensitive measures and a failure to control for partial information. His 1960 review in Psychological Review surveyed the literature and evaluated it experimentally, and is a standard reference in later debates about unconscious perception.

Information theory and converging operations

With Harold Hake, Eriksen published a series of papers in 1955 applying information theory to human discrimination, among the earliest such applications in psychology. A related study with Wechsler used the same framework to show that anxiety affected response variability rather than perceptual discrimination itself. Throughout this work Eriksen pressed a methodological principle he called converging operations: no single experiment can isolate a mental process, so conclusions must rest on several procedures with different and complementary weaknesses.

The flankers task

The paradigm for which Eriksen is best known was introduced in a 1974 paper in Perception & Psychophysics under the names of B. A. Eriksen and C. W. Eriksen. Participants identify a central target letter flanked by noise letters that are either compatible with the required response or incompatible with it. Responses to incompatible arrays are slower and more error-prone, and the size of that interference indexes how well irrelevant information is excluded from processing.

The elegance of the design is that the distractors are known, visible and irrelevant, so the task isolates the cost of unresolved competition without invoking memory, search or strategy. It has become one of the most widely used instruments in experimental psychology and cognitive neuroscience, appears in developmental and clinical batteries such as the Attention Network Test, and is routinely deployed as a marker of executive attention, conflict processing and inhibitory control.

The continuous flow model

In 1979, with David Schultz, Eriksen proposed that information flows continuously from perceptual analysis to response preparation rather than passing through a series of discrete stages that must complete before the next begins. On this account partial information accumulates and can begin priming a response before processing is finished, which explains why incompatible flankers slow responses: competing response tendencies are being continuously and simultaneously activated. The paper was an important challenge to the discrete-stage models dominant at the time and a precursor to the sequential sampling models now standard in the field.

Spatial cueing and the zoom lens of attention

Eriksen was among the first to use spatial precues to direct attention to a location and measure the resulting benefit, a technique that underpins the Posner cueing tradition and most modern work on orienting. With John St. James he proposed a zoom lens model in which the attended region can expand or contract, with resolution traded against area: attention focused on a small region yields fine discrimination there and poor discrimination outside it.

Major Publications

  • Eriksen, C. W. (1951). Perceptual defense as a function of unacceptable needs. Journal of Abnormal and Social Psychology, 46, 557–564.
  • Eriksen, C. W. (1960). Discrimination and learning without awareness: A methodological survey and an experimental evaluation. Psychological Review, 67, 279–300.
  • Eriksen, C. W., & Hoffman, J. E. (1972). Temporal and spatial characteristics of selective encoding from visual displays. Perception & Psychophysics, 12, 201–204.
  • Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143–149.
  • Eriksen, C. W., & Schultz, D. W. (1979). Information processing in visual search: A continuous flow conception and experimental results. Perception & Psychophysics, 25, 249–263.
  • Eriksen, C. W., & St. James, J. D. (1986). Visual attention within and around the field of focal attention: A zoom lens model. Perception & Psychophysics, 40, 225–240.

Eriksen also published a series of 1955 papers with Harold Hake applying information theory to discrimination, early landmarks in the use of that framework in psychology.

Impact and Legacy

Eriksen's influence is diffuse because so much of it has been absorbed into the background of the field. Visual search, rapid serial presentation, temporal integration and masking, spatial cueing, the stop-signal paradigm and the flankers task are all methods he pioneered or helped establish, and a great deal of contemporary research on perception, attention and cognitive control runs on instruments he built. Attention, Perception, & Psychophysics devoted a special issue to research inspired by his work in 2020.

The flankers task, his most cited contribution, has also become a test case in a live methodological dispute. Its interference score is conventionally interpreted as a measure of inhibitory control or executive attention, but that reading has been increasingly questioned. Kenneth Paap and colleagues reported in 2020 that flanker, Simon and spatial Stroop interference scores have inadequate concurrent and convergent validity, correlating only weakly with one another and with the individual-difference variables they are supposed to predict. Alodie Rey-Mermet, Miriam Gade and Klaus Oberauer had argued on similar evidence that tasks used to assess inhibition do not measure a common underlying construct but rather task-specific abilities to resolve the interference each task happens to generate. Latent-variable work points the same way: in the later revisions of Akira Miyake and Naomi Friedman's model of executive function, the inhibition component is no longer separable from a common executive factor, and the flanker effect typically loads weakly on executive attention factors.

A second problem is taxonomical. Paap's factor analyses found that Simon, spatial Stroop and vertical Stroop tasks cluster together while the flanker task does not, which fits the view that flanker conflict is resolved by spatially attending to the target rather than by inhibiting competing representations. If so, calling the flanker effect a measure of inhibition misdescribes what the task does. Interference scores also fail to correlate with trait measures of self-control and impulsivity, so they should not be read as indices of those traits without converging evidence. None of this undermines the paradigm's usefulness for studying attention; it does mean the common shorthand in which a flanker effect just is inhibitory control is not supported.

A smaller but real issue concerns credit. The 1974 paper lists Barbara A. Eriksen as first author, and the task is conventionally named for Charles alone. His colleagues' memorial accounts make clear the work was a collaboration, and the asymmetry is a familiar one in the history of psychology.

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References

  • Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16(1), 143-149.

Last updated: 2026-10-20

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