Simon Effect

Background

Simon & Rudell (1967) discovered that the spatial position of a stimulus affects response speed even when position is irrelevant to the task. This phenomenon is now known as the Simon effect.

The Simon Effect

When stimulus location corresponds with response location (congruent), responses are faster than when they don’t correspond (incongruent). The typical effect size is 20–40 ms.

Why It Happens

Stimulus location automatically activates a spatial response code that either facilitates or interferes with the correct response. Even though position is irrelevant to the task, the brain cannot ignore it—the spatial information is processed automatically and influences the selection of a motor response.

References

Simon, J.R. & Rudell, A.P. (1967). Auditory S-R compatibility: The effect of an irrelevant cue on information processing. Journal of Applied Psychology, 51, 300–304.
Lu, C.H. & Proctor, R.W. (1995). The influence of irrelevant location information on performance: A review of the Simon and spatial Stroop effects. Psychonomic Bulletin & Review, 2, 174–207.

A colored circle (RED or BLUE) will appear on the LEFT or RIGHT side of the screen.

Respond to the COLOR only — ignore the position!

Press the key corresponding to the color:

F = Red J = Blue

There are 80 trials total (~4 minutes). Respond as quickly and accurately as possible.

Simon Effect

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