Simon Effect
People respond faster and more accurately when the location of a stimulus matches the location of the response, even when stimulus location is irrelevant to the task.
When to Use
Align controls with their effects
Place controls in locations that match where their effects will appear (e.g., left control for left-side effect).
Use spatial compatibility
Design interfaces where the spatial arrangement of controls matches the spatial arrangement of their effects.
Consider natural mappings
Leverage users' natural tendency to associate locations with responses.
When to Avoid
Don't create spatial conflicts
Avoid placing controls in locations that conflict with where their effects appear, as this will slow users down.
Origin
The Simon Effect was discovered by J. Richard Simon in the 1960s. His research showed that people respond faster when a stimulus appears in the same location as the required response, even when the stimulus location is not relevant to the task. This demonstrates the importance of spatial compatibility in interface design.