Stimulus-response dimensional overlap elicits a decreasing Simon effect along the vertical dimension

In Simon task, the response is faster when stimulus and response locations are spatially correspondent than when they are on opposite sides (Simon effect – SE). The SE was found with both horizontal and vertical stimulus-response arrangements. The horizontal SE decreases as reaction times increase. In contrast, the vertical SE does not decay over time. In this work, we investigate the vertical SE when both stimuli and responses are located along the vertical dimension. Results showed a decreasing SE occurring along the vertical dimension suggesting that similar underlying mechanisms may be involved both for the horizontal and vertical Simon effects.