Simon effect

The Simon effect is the difference in accuracy or reaction time between trials in which stimulus and response are on the same side and trials in which they are on opposite sides, with responses being generally slower and less accurate when the stimulus and response are on opposite sides. The task is similar in concept to the Stroop Effect. The Stroop Color and Word Test (SCWT) can be used to assess the ability to inhibit cognitive interference that occurs when the processing of a specific stimulus feature impedes the simultaneous processing of a second stimulus attribute. The Simon effect is an extension of this effect, but the interference in this task is generated by spatial features rather than features of the stimuli themselves.