The Simon effect and responses to aircraft dials

The paper examines the relevance of the effects of irrelevant task stimuli (the Simon Effect; Simon, 1990) to performance on reading aircraft dials. Furthermore it examines whether the spatial relationship between stimulus items of the display and the position of the participant’s hand is a factor in the Simon Effect. Participants responded to consecutive representations of an analogue aircraft dial, via two spatially compatible response keys. Response time was the dependent variable. Analysis of hand arrangement, dial quadrant dial pointer starting angle and direction of dial pointer movement found significant main effects of quadrant and starting angle. Planned comparisons revealed that responses to dial pointer movements differed in each quadrant of the dial, such that the Simon Effect was causing a facilitating quadrant, an interfering quadrant and two neutral quadrants. Previous explanations of the location of the Simon Effect were upheld. Responses to oblique starting angles were significantly slower than to vertical or horizontal ones.