As predicted, the reaction time of the groups increased based on the relative position of the light stimulus (age was not a factor).
A typical demonstration of the Simon effect involves placing a participant in front of a computer monitor and a panel with two buttons.
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 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.
According to Simon himself,[6] the location of the stimulus, although irrelevant to the task, directly influences response selection due to an automatic tendency to 'react towards the source of the stimulation'.
Although other accounts have been suggested,[7] explanations for the Simon effect generally refer back to the interference that occurs in the response-selection stage of decision-making.