Simon Effect - Method

Method

A typical case of the Simon effect involves placing a participant in front of a computer monitor and a panel with two buttons on it, which he or she may press. The participant is told that the button on the right corresponds to red and to press the button on the right when they see something red appear on the screen. They are told that the button on the left corresponds to green and to press the button on the left button when they see something green appear on the screen. Participants are usually told to ignore the location of the stimulus and base their response on the task-relevant color.

Participants typically react faster to red lights that appear on the right hand side of the screen by pressing the button on the right of their panel (congruent trials). Reaction times are typically slower when the red stimulus appears on the left hand side of the screen and the participant must push the button on the right of their panel (incongruent trials). The same, but vice versa, is true for the green stimuli.

This happens despite the fact that the position of the stimulus on the screen relative to the physical position of the buttons on the panel is irrelevant to the task and not correlated with which response is correct. The task, after all, requires the subject to note only the colour of the object (i.e., red or green) by pushing the corresponding button, and not its position on the screen.